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As with many things in nutrition, the ketogenic diet is surrounded by myths, misinformation, and exaggeration. The truth about keto is that while it’s better than alarmists would have you believe, it’s not the panacea that your best friend thinks it is.

What are the benefits of keto? What are the risks? Is keto a diet you should follow long-term? What supplements should you use on keto?

Whether you’re brand new to the diet, or you’re a nutrition coach and need some talking points to use with clients, this guide will give you answers to questions you’ve been asking — and answers to questions you haven’t asked yet.

Intro: Keto Experimentation, Experience, and Research

It’s been over a decade since I wrote my first article on low-carb or ketogenic diets. Since that time, experience, experimentation, and research have taught us a lot.

  • The ketogenic Diet is a powerful tool to help someone reclaim their health.
  • In the short-term, the diet offers numerous health benefits.
  • In the long-term, the benefits of the diet are less certain, and potential negative impact on mental and physical well-being needs to be considered.
  • Short-term use of the ketogenic diet can be beneficial for most people. Long-term adherence to the diet is unnecessary and potentially detrimental.

What Is Keto?

Keto is short for “ketogenic diet,” a diet pattern that significantly limits carbohydrates, emphasizes dietary fat, and causes low levels of glycogen in order to stimulate production of ketone bodies.

Elevated ketones make a ketogenic diet “ketogenic,” and separate a ketogenic diet from a standard low-carb diet.

Your liver produces endogenous ketones (or ketone bodies) in response to starvation, fasting (even intermittent fasting), or when you’re on a very low-carb, high-fat diet. Exercise, when it’s intense enough and done for long enough, also stimulates ketone production.

In the absence of available carbs, ketones become a preferred energy source.

Ketosis vs. Ketoacidosis

For years, the medical community warned people against the ketogenic diet, confusing nutritional ketosis for ketoacidosis.

Ketoacidosis most often occurs in people with undiagnosed type 1 diabetes, or in patients with type 1 diabetes who don’t use their insulin. For people with type 1diabetes, ketoacidosis can be life-threatening.

In the complete absence of insulin, the body breaks down fat at an accelerated rate, and produces very high levels of ketones. The concentration gets so high that the blood becomes acidic.

In rare cases, ketoacidosis occurs in people with severe type 2 diabetes, in alcoholics, from starvation, and has even been seen during pregnancy.

Nutritional ketosis is a diet strategy used to maximize ketone production and may increase the metabolism of stored body fat. Though nutritional ketosis and ketoacidosis are both states where ketone bodies are elevated, the concentration is much higher in ketoacidosis.

Today, a plethora of research shows that a ketogenic diet is safe for most people and distinctly different from ketoacidosis.

Keto For Disease Treatment

The ketogenic diet was first used in the 1920s as a treatment for epilepsy.

Patients were put on diets consisting of 80 percent or more of their calories coming from fat. Protein was limited to about 0.45 grams per pound body weight per day.

Not only did patients experience fewer seizures, they also improved blood sugar, insulin, and lipid levels while reducing body fat.

Keto Macronutrients For Disease Treatment

Doctors may put patients on the therapeutic version of a ketogenic diet for treating diseases like epilepsy, certain types of cancer, type II diabetes, etc. The general outline of a therapeutic ketogenic diet is extreme and may be necessary for dealing with medical conditions.

  • Dietary fat makes up 80% or more of total daily calorie intake
  • Protein limited to 0.45 grams per pound body weight per day
  • Carbohydrates limited to 20-30 grams per day, or less

This extreme version of a ketogenic diet causes ketone levels in the blood to rise to 3.0 mmol/L or higher. At this “deep state of ketosis,” seizure rates drop significantly. Since 1920, the ketogenic diet has been used in the treatment of other metabolic and neurological diseases.

Dr. Thomas Seyfried researches the ketogenic diet and cancer, and feels that a higher range of 3.0 to 6.0 mmol/L is necessary for cancer treatment.

While the high level of ketones may be necessary when treating neurological and metabolic disease, it isn’t necessary, and could be detrimental for those pursuing general health and fitness.

Unfortunately, many people who evangelize the benefits of keto don’t know the difference and suggest the disease-treatment version should be used for generally healthy people. It should not.

Level of Ketosis Blood Ketones
Light Ketosis 0.5–1.0 mmol/L
Nutritional Ketosis (optimal) 1.0–3.0 mmol/L
Therapeutic Ketosis 3.0–6.0 mmol/L

Keto For Health, Fitness, and Improved Body Composition

Jeff Volek and Steve Phinney, leading experts in ketogenic and low-carb diets, coined the term “nutritional ketosis” to describe the optimal ketone concentration for health and fitness.

Nutritional ketosis can produce up to 150 grams of ketones per day.

Keto Macronutrients For Health, Fitness, and Body Composition

I often recommend using nutritional ketosis as a starting point for weight loss and improved health. The closer you get to “optimal” health, fitness, and body composition, the more I would recommend transitioning away from keto, and towards a diet higher in protein and carbohydrates (and lower in fat, of course).

To reach nutritional ketosis, most people follow something like this:

  • 0.75 grams of protein per pound body weight per day
  • Net Carbohydrates 30-100 grams per day, depending on level of activity and fitness
  • Fat fills in the remainder of the daily calorie needs

What are net carbs? Net carbs, often displayed on food packaging, are the total grams of carbohydrates minus fiber. Fiber isn’t digested like normal carbohydrates, and has no effect on blood sugar and insulin levels. Therefore, carbohydrate counts on keto consider “net carbs.”

Keto is often promoted with the idea of eating unlimited amounts of fat. Though a ketogenic diet might provide a metabolic advantage, calories do still count.

If you’re binging on bacon, butter, and cheese, there’s no need for your body to use the fat you’ve stored under your skin.

The percentage of fat you eat compared to carbohydrates and protein is high, but that doesn’t mean you can eat unlimited amounts of fat.

I also need to address the fear of protein when following keto.

The keto community has created a fear of eating protein because protein raises insulin. Yet, that’s exactly how things are supposed to work. Insulin helps shuttle protein’s amino acids into your cells. The importance of sufficient protein intake far outweighs the effect of a temporary rise in insulin. 

Because protein raises insulin slightly, a rise in insulin could take you temporarily out of ketosis. That’s a concern for a patient with epilepsy, as it could induce a seizure.

For general health, it’s more important to get enough protein to support growth or maintenance of muscle than it is to stay in ketosis 24/7.

Read More: What You Need to Know About High-Protein Diets

Keto Diet Health Benefits

The volumes of supporting research for low-carb and ketogenic diets are more than convincing, especially when applied to the average overweight and insulin-resistant adult. 

The health benefits of keto are what appear to be accurate, based on today’s existing body of research. It’s possible, likely even, that in 20 years, we’ll know and understand our bodies differently than we do today. 

1. Restores Mitochondrial Function

Keto improves the function and can increase the size and number of your mitochondria.

This is likely the most important benefit of keto (I know . . . you thought the ultimate benefit was bacon. Sorry to be a buzzkill). 

Mitochondria are the power plants of your cells. They generate adenosine triphosphate (ATP), the ultimate unit of energy. You need ATP to move, breathe, digest food, and read this article. Without mitochondria and the ATP they produce, you would have no life.

Most diseases either cause mitochondrial dysfunction or mitochondrial dysfunction contributes to the disease.

The causes of mitochondrial dysfunction include:

  • Excessive carbohydrate consumption or high blood sugar
  • Sedentary lifestyle
  • Insufficient sleep
  • Exposure to excessive free radicals
  • Insufficient micronutrient intake
  • Exposure to environmental toxins

Although mitochondria produce free radicals on their own simply by producing energy, the modern lifestyle and diet exposes our bodies to higher levels than our bodies can handle on their own.

Antioxidants from coffee, vegetables and fruits, and a high-quality multivitamin help combat some of the free radicals. But that might not be enough.

Keto supports mitochondrial function by minimizing reliance on sugar, maximizing use of fat, reducing inflammation, and creating a more efficient energy source: ketones.

As your mitochondrial function improves and you feel better, you move and exercise more, which further stimulates mitochondrial biogenesis.

2. Supports Significant Weight Loss

At least in the short-term, keto is extremely effective for weight loss, and possibly superior to other diets for fat loss.

The actual cause of the better weight-loss benefits remains to be discovered. Many theories exist, and all probably contribute to weight loss.

What Causes Weight Loss On A Ketogenic Diet?

The following are the five theories on why keto is so effective for weight loss. More than likely each of the theories is involved:

  1. Reduction in hunger, due to the appetite-suppressing effects of protein and ketones
  2. Decreased need for calories, since fat stores provide more of the body’s energy needs
  3. The high “metabolic cost” of creating glucose from protein/amino acids, which could burn up to 600 calories per day
  4. Reduced cravings for carbohydrate-rich foods since blood sugar stays steady
  5. Hormonal shifts, such as increases in growth hormone and testosterone

In my opinion, it doesn’t matter how it works better. Low-carb and ketogenic diets lead to better, easier weight loss, and are easier to adhere to than calorie-controlled low-fat diets. That’s often all that matters for the average person.

To be fair, some research studies show little to no difference in weight loss between low-carb/keto and low-fat/low-calorie diets. However, these are often studies where researchers follow up with people months to years after they start a diet to see what kind of results they’ve gotten. 

Of course, most people don’t stick to the diet long-term, and the different diet groups end up eating more alike than different.

If you follow the diet, it works. If you don’t, it doesn’t. That’s why long-term studies show no differences in weight loss between low-carb and low-fat diets. It’s not because the diet doesn’t work: It’s because long-term, most people don’t work the diet.

A 2018 study published in the Journal of the American Medical Association (JAMA) showed that after 12 months, “there was no significant difference in weight change between a healthy low-fat diet vs a healthy low-carbohydrate diet.” 

I was curious about what they were calling “low-carb” versus “low-fat.”

It turns out, the low-fat diet group ate an average of 48% of calories from carbohydrates. The low-carb ate a considerable amount of carbs too: 30%! On a 2000-calorie diet, that would be a whopping 150 grams per day. 

In my opinion, that’s hardly “low-carb.” Of course, most news sources failed to consider this when they promoted headlines suggesting low-carb wasn’t more effective than a low-calorie diet.

3. Improves Insulin Sensitivity and Blood Sugar Levels

Since carbs cause elevated blood sugar, and over time, chronically elevated blood sugar leads to insulin resistance, it should come as no surprise that keto improves average blood-sugar levels and helps restore insulin sensitivity.

Those on a ketogenic diet often see a significant improvement in HbA1c, fasting blood sugar and insulin levels.

Besides limiting the damage the carbs do, ketones can improve glucose uptake as well.

4. Improves Sex Hormone Balance in Men And Women

Chronically elevated glucose causes different responses in men than in women.

Chronically elevated blood sugar and insulin decrease testosterone and increase estrogen in men, and increase testosterone and decrease estrogen in women.

In men, low testosterone contributes to depression, muscle loss, lack of motivation, cognitive problems, infertility, grumpy old man syndrome (even when a guy isn’t “old”), and moobs . . . man boobs.

In a study of healthy, college-aged, resistance-trained men, when compared to a Standard American Diet, a ketogenic diet increased testosterone. The men in the ketogenic group increased testosterone from an average of 570 ng/dL to 690 ng/dL, about a 21 percent increase. 

What increases testosterone in the short-term for men on keto? Theories include:

  • Increased cholesterol consumption, as cholesterol is a building block for testosterone.
  • Lower fiber intake, since fiber helps remove cholesterol (I have my doubts about this one, since fiber also helps remove estrogen).
  • Lower belly fat (visceral fat). This fat has been found to increase estrogen and lowers testosterone, so reducing it is key.

In my opinion, a low-carb, but-not-ketogenic, high-protein diet would have done the same thing. 

Chronically high insulin in women affects testosterone and estrogen in the opposite directions of men. Testosterone goes up and estrogen stays the same or goes down.

When testosterone gets too high in comparison to estrogen, women develop “central obesity.” They get more of an apple shape than a pear shape. They lose their curves.

Excess testosterone in women:

  • Increases facial hair growth
  • Contributes to infertility
  • Increases heart-disease risk
  • Causes abnormal cycles
  • Raises triglycerides
  • Raises inflammatory levels
  • Causes central obesity — women develop more of an apple shape than a pear shape (they lose their curves)

These are classic signs of polycystic ovary syndrome (PCOS). It’s no surprise then, to find that women who follow a ketogenic diet often experience significant improvements in PCOS symptoms.

5. Improves Markers Of Cardiovascular Health

Your ratio of triglycerides to high-density lipoproteins (HDL) is one of the simplest and most telling indicators of cardiovascular disease risk.

 Triglycerides / HDL Ratio Risk Level 
1:1 or less Optimum
2:1 Low Risk
3:1 Moderate Risk
4:1 High Risk

Triglycerides rise when you eat a lot of carbs. They fall when you restrict carbs.

Not surprisingly, a ketogenic diet dramatically improves this ratio.

Cholesterol levels responds less predictably than triglycerides with ketogenic diets. In some, cholesterol levels go up. In others, it goes down. However, cholesterol by itself is a poor predictor of cardiovascular risk anyway.

If you still worry about eating more cholesterol on a ketogenic diet, consider the findings of a published review of available research from 2011 in the British Journal of Nutrition:

Epidemiological data do not support a link between dietary cholesterol and CVD (cardiovascular disease).

Lecerf JM, de Lorgeril M

Research also shows ketogenic diets protect heart muscle tissue by reducing free radicals, as well as improving its efficiency and energy reserves. Animal models also show ketosis even prevents heart-tissue damage from heart attacks and strokes.

6. Possibly Augments Cancer Treatment

Most cancer cells thrive on glucose. An excessively high-carbohydrate intake could cause mitochondrial dysfunction, which could cause cancer-cell development.

This does not mean carbs cause cancer. It simply means that when someone consumes enough to cause mitochondrial damage, they could contribute to cancer-cell development. 

And, if those cancer cells begin to multiply, they’ll grow best in a glucose-rich environment.

A number of animal studies have shown that a ketogenic diet slows tumor growth, which sounds promising. It appears that most cancer cells cannot use ketones, so a ketogenic diet robs most cancer cells of their fuel source, while providing an alternative fuel for healthy cells.

However, we’re far from a definitive answer in how much of an effect a ketogenic diet would have on cancer-cell growth. 

A group of researcher found evidence that breast cancer cells can use ketones to actually fuel their growth. They concluded:

. . . Given our current findings that ketones increase tumor growth, cancer patients and their dietitians may want to reconsider the use of a “ketogenic diet” as a form of anticancer therapy.

Bonuccelli, et al.

Most evidence suggests a ketogenic diet might help and probably wouldn’t hurt in supporting cancer therapy. However, there is no evidence at this point that a ketogenic diet prevents cancer. I’m stressing this because there’s a lot of bad advice on the Internet that might make it sound like “keto cures cancer.” The research does not support that statement at this time.

7. Improves Brain- and Nervous-System Function

As I mentioned earlier, the ketogenic diet has a significant impact on reducing the occurrence of seizures — that’s really how the diet first got popular. It has even been shown to be effective in treating infantile spasms, a rare form of epileptic seizure.

Some people who eliminate seizures with a ketogenic diet remain seizure-free, even after transitioning to a more “normal” diet, which suggests the ketogenic diet may fix the cause of the seizures. How cool is that?

Other nervous system-related conditions where keto may help include:

  • Parkinson’s and Alzheimer’s disease
  • Multiple sclerosis
  • Traumatic brain and spinal cord injuries
  • Brain cancer
  • Autism
  • Sleep disorders
  • Migraine headaches
  • Depression

Ketone bodies may also be neuroprotective in degenerative brain diseases, not necessarily curing the diseases, but perhaps slowing their progression. A ketogenic diet may also help slow memory loss and confusion associated with dementia.

8. Slows Effects of Aging

A ketogenic diet (as well as intermittent fasting) creates a similar metabolic effect as chronic calorie restriction, without restricting calories.

It reduces free-radical production. Free radicals are the main cause of aging and cell death. Keto also reduces inflammation, which causes pain and tissue damage. As I mentioned above, it can also be neuroprotective. 

This is why keto is thought to possibly enhance longevity, but it’s theoretical at the moment. Fortunately, if it does enhance longevity, it does so without sacrificing quality of life as chronic calorie-restriction does.

9. Enhances Some Types Of Exercise Performance

Aerobic-endurance athletes do well on a ketogenic diet. Aerobic exercise relies on efficient use of fat for fuel, which the ketogenic diet clearly provides. 

It may be helpful in intermittent aerobic sports, such as baseball, basketball, and soccer, where athletes have short bursts of sprints intermixed with longer periods of slower movement and running.

For general fitness and muscle-building in experienced lifters, a ketogenic diet doesn’t seem to provide any advantage for those who are healthy. 

Keto may be detrimental for:

  • Strength
  • Power
  • Muscular endurance
  • Cycling
  • Swimming
  • Mountain biking
  • Boot camp, metabolic conditioning, or other forms of high-intensity training

Keto Diet Side Effects

The skeptics often ask, “What are the dangers of keto?” or “What are the keto diet side effects?” While I wouldn’t go so far as to say there are dangers of keto, there are some risks to consider when following the ketogenic diet long-term.

The mental, emotional, hormonal, cardiovascular, digestive, performance, and skeletal effects after years of following the diet for humans haven’t been vetted out yet. It’ll probably be a decade or two before we understand what happens when we restrict carbohydrates indefinitely.

The following are some of the long-term risks to consider when staying on keto after you achieve a solid level of health and fitness.

1. Chronically Elevated Cortisol

Physical, mental, or physiological stress stimulates cortisol secretion. An angry boss, sleep debt, and excessive cardio are obvious stressors.

However, cortisol is also released when your body’s physiology gets out of balance.

Cortisol rises when your blood sugar is low in order to get glucose into your bloodstream. It does so by stimulating gluconeogenesis, the formation of glucose from amino acids. The amino acids come from either your diet or muscle tissue.

In the long-term, this could lead to muscle loss, especially if you don’t eat enough protein. Elevated cortisol also causes low testosterone in men and women.

Also, since keto could cause a stress response in some people, I would recommend not following a ketogenic diet if you are

  • Dealing with adrenal fatigue (also known as HPA Axis Dysregulation)
  • The parent of a newborn
  • An athlete in the midst of high-volume training
  • Under significant work, financial, or relationship stress, unless the cause of that stress would be reduced by getting your health and body composition under control

2. Growth-Hormone Suppression and Resistance

Growth hormone stimulates fat metabolism and metabolic rate, supports muscle tissue growth and repair, and enhances thyroid function. It also increases ketone production.

Growth hormone levels increase in response to fasting, intense exercise, deep sleep, low blood sugar, and injury or trauma.

Theoretically, your low blood sugar from a ketogenic diet should stimulate growth hormone. However, there’s another factor that’s often overlooked.

Elevations in fatty acids blunt growth hormone secretion.

And what does a high-fat, ketogenic diet do? It increases fatty acid availability by either releasing more fatty acids from stored body fat or from the higher levels of fat you consume on the diet.

One of the best ways to mitigate the blunting of growth hormone is to take a break from eating between meals. Growth hormone rises about three to four hours after a meal, when fatty acid or glucose levels fall.

But if you eat dark chocolate, nuts, drink fat-filled coffee, or consume other calorie-filled snacks between meals, you never reach a post-meal fasting state, which means your keto snacks could stifle growth-hormone secretion.

Where carbs and fat blunt growth hormone, protein actually stimulates growth-hormone release. It’s one of the many reasons I recommend at least 0.75 grams of protein per pound ideal body weight each day on keto, assuming you’re not treating a disease with the diet.

One other potential issue is growth-hormone resistance. A 2011 animal study by Bielohuby, et al., showed that a very low-carbohydrate diet caused the liver to become growth-hormone-resistant, meaning growth hormone didn’t stimulate IGF-1 production normally.

Growth hormone doesn’t act directly on tissues to stimulate growth. It acts on insulin-like growth factors, with insulin-like growth factor-1 (IGF-1) being the most prominent. 

It appears that the diet helps reduce or eliminate seizures by decreasing or suppressing IGF-1, as well as mammalian target of rapamycin (mTOR). While that’s good for controlling seizures, it could be detrimental for lean body mass. Both IGF-1 and mTOR are factors in muscle growth. 

3. Chronically Low Insulin

While chronically high insulin is certainly a problem, keeping insulin too low for too long could also present some problems.

Insulin is an extremely powerful anabolic hormone. Yes, it can cause fat gain when insulin, carbs, fat, and total calories are too high. But, it also enhances muscle growth by increasing amino-acid uptake in muscle cells.

Without insulin, it will be increasingly difficult to build muscle and recover from strength-training sessions.

In addition, low insulin might have a negative effect on your brain.

Recent research shows that insulin does more than store fat and amino acids. Insulin seems to be neuroprotective for your brain, and supports learning and memory. It also could slow the aging process.

The problem with insulin might not be insulin itself, but rather the resistance of cells to respond to insulin’s signals.

As I mentioned earlier, there is little long-term research on the effects of a ketogenic diet. As it stands today, I believe carbs should be part of one’s diet, once he or she has restored insulin sensitivity.

4. Low Thyroid

Thyroid function declines on a low-carb or ketogenic diet. Those on the pro low-carb side say this is a natural effect from the body shifting fuel substrates.

Those on the anti-low-carb side often use the thyroid response as reason to recommend against it.

If you have hypothyroidism, and your treatment plan keeps your levels in an optimal range, check your levels again within two to three months after starting keto, and see if there’s a change.

Besides a change in thyroid, you might notice an increase in cholesterol, a decrease in energy, or other hypothyroid symptoms.

A complete thyroid panel includes TSH, T3, T4, reverse T3, and Thyroid Peroxidase (TPO).

If you have symptoms of hypothyroidism, and you’ve never gotten medical help, I would not recommend keto.

Read More: Low Thyroid: Causes, Symptoms, and Solutions

5. Digestive Dysfunction

Everyone agrees that the gut is a significant part of the immune system. It also acts like a second brain. Much of its value comes from the bacteria that live there.

Your gut can help you feel good through the production of neurotransmitters like serotonin. It can also make you feel miserable through autoimmune reactions and inflammation.

Excessive carbohydrates, and especially sugar, help bad bacteria spread like a California wildfire. Yet, even good gut bacteria needs some carbs, and especially fiber, to flourish. 

We don’t know what the long-term effects of eating enormous amounts of fat, and little to no carbohydrates might do to the microbiomes of large populations of people.

Interestingly, researchers feed animals a high-fat diet to cause systemic inflammation and a breakdown of the gut lining. Then, they test various therapies to see how well they reduce the inflammation they triggered with the high-fat diet.

Some evidence, mainly from animal research, suggests that a high-fat intake increases cardiovascular disease risk by increasing production of endotoxins, also known as lipopolysaccharides (LPS). 

No, we’re not rats or mice. But, it’s the increased fat that causes endotoxins, which increase inflammation.

One way to avoid this is by consuming more of your fat as medium-chain triglycerides (MCTs), as opposed to standard dietary fats. MCTs are metabolized differently and don’t trigger LPS production.

From the existing research, a low-carb, high-fat diet in humans seems to lower levels of inflammation in the short-term. But there’s still much that’s unknown about the long-term changes of gut bacteria and the health of the gut lining itself.

To me, the biggest concern related to digestive health on keto is getting enough fiber. 

Without sufficient fiber, your gut bacteria have no food. Without food, they die. The lettuce wrap around your bacon double-cheese burger isn’t enough quality fiber to feed your good bacteria.

Good bacteria produce neurotransmitters like serotonin. They also use prebiotic fibers like fructooligosaccharides to produce short-chain fatty acids (SFAs). The cells lining your gut then use the SFAs as an energy source, helping those cells thrive and multiply.

Without the SFAs, your gut lining breaks down, leading to autoimmune issues, as well as potential changes in mood and emotional state.

6. Depressed Mood and Emotions

Keto can help calm the mind and increase clarity and focus for those with hyperactivity or anxiety.

But what about those who are already chilled out, stoic, or emotionally reserved? Those who don’t get overly excited, but also don’t wig out over the unexpected? Could the lack of carbs leave some types of people feeling depressed? 

There isn’t much research to answer these questions. Anecdotally, there are many examples of people who feel flat, depressed, or melancholic on keto.

When it comes to brain chemistry, people respond in opposite ways to certain substances. For example, I’ve seen this phenomenon with supplements and essential oils.

Perhaps you’ve seen it at a relatives wedding reception: One friend is the life of the party after a few drinks, the other is asleep in a corner.

Observational studies have shown that LChD (low-carb diets) with high protein and fat concentrations are associated with higher levels of anxiety, anger, stress, mood disturbances, fatigue, depression, poor physical exercise performance, and less vigor and imagination.

Frigolet et al.

One caveat: Almost everyone feels lousy during the adaptation period from sugar-burning to fat-burning. That’s not a problem with the diet or a reason for you not to do it, it’s simply your brain and body getting over its dependence on glucose. It’s known as the keto flu.

So, don’t be surprised if you initially feel tired, ornery, irritable, or fatigued. You’ll just have to muster up some resilience and get through it.

However, if you’ve been on keto for a while, and you’re no longer feeling like yourself, it might be time to eat some carbs.

On a personal note, I followed a low-carb or ketogenic diet for several years. I was so used to feeling emotionally and physically “flat” that I didn’t realize how off I felt. It wasn’t until I started tinkering with eating carbs at dinner more often that I started feeling (and sleeping) more like my old self.

7. Decreased Physical Performance

Keto is great for some types of endurance sports. Studies show fat oxidation, endurance, and peak power improve after adapting to a ketogenic diet.

However, keto doesn’t offer much benefit in power, strength, and glycogen-dependent sports and exercise. It could actually be detrimental for some sports.

If you’re brand new to exercise, and you’re not under significant amounts of stress, you’ll probably do well combining keto and a good strength training program.

If you’ve been training for years and start a ketogenic diet, it’s possible you’ll experience a drop in strength, muscular endurance, and overall stamina. 

Even for aerobic exercise, the performance improvements don’t always come from increased fatty-acid utilization, but rather from the availability of ketones. It could be more effective for endurance athletes to continue to eat carbs and supplement with exogenous ketones (explained below), rather than follow a ketogenic diet with or without ketones.

For every hardcore ketogenic athlete you find, you can find another who bonked, tanked, or crashed while trying to train hard following a ketogenic diet. There’s a high level of individuality for keto and sports performance.

Here’s what I often tell others starting a ketogenic diet:

If you’re overweight, do keto until you reach a plateau in weight loss, energy levels, or performance.  If that plateau lasts more than a couple of weeks, eat an evening meal with whatever carbs you want, and see what happens over the next few days with your weight, performance, and energy levels.

Stick with it until it doesn’t work. Then eat your fill of carbs for dinner one night and see what happens. You’ll probably notice the weight starts coming off again, and your mood, energy, and performance improve for a while.

Then, when you hit a plateau again, eat the carbs for an afternoon again. You might benefit from including them on an occasional (possibly weekly) basis.

Top 9 Keto Diet Mistakes

Keto is rigid, but it’s simple. If you follow the rules of the diet, you have a very high probability of getting results. If you make up your own rules, or stick to it only when it’s convenient, you will probably fail.

The following are the top mistakes people make on the ketogenic diet.

1. Doing Keto Mostly Sometimes

I think our son Jacob coined the phrase “mostly sometimes” when he was around 10 years old. If you asked him, he “mostly sometimes” cleaned his room, brushed his teeth, and was nice to his brother.

He knew knew the “right answer” was yes, the “real answer” was no, and so he came up with a middle-ground answer. Mostly sometimes.

Many keto dieters believe they follow a ketogenic diet, but when you ask them what they ate that day or the day before, or the day before that, they realize they’re doing keto mostly sometimes.

Keto is not a “mostly sometimes nutrition plan.” It is a diet.

Let me put it another way: If you half-heartedly follow keto and eat more carbs than you should, it’s probably the worst nutrition plan you could follow. Combining carbs with a high-fat diet screws up lipid profiles, causes weight gain, and well, leads to almost all of the health problems people face today, since that’s pretty much the Standard American Diet: Lots of fat, too much carbohydrate, and too little protein.

You’re either in or out. All the time. Not mostly sometimes.

2. Not Maintaining Monogamy

When I trained clients one-on-one, I often told them that if they wanted to work with me, they had to be monogamous.

I didn’t want them to follow my nutrition and exercise plan for a couple of weeks, and then start something else because their best friend just started it or because it came packaged with a sexy-looking supplement. 

I didn’t want them adding in a P90x workout on their off days or doing an extra boot camp class after our sessions. 

I knew that if they jumped from one program to the next, they’d never make progress.

It’s not that I believed I was the end-all-be-all trainer and nutrition coach. It’s that I knew they they’d get results if they followed my program consistently, and they wouldn’t if they mixed in other stuff that wasn’t part of the program. 

What I find is that people get a week or two into a diet, and then they start looking at other diets, thinking there’s a better option out there. 

They’re all in on keto for a week. Then they’re onto paleo and loading up on sweet potatoes. The next week they’re back to keto, and suffering through another fat-adaptation phase. Then, they’re onto intermittent fasting and eating carbs at night. And then they join a friend for a Weight Watchers meeting where Oprah woos them into eating whatever they want.

Five diets in five weeks and they can’t figure out why things won’t work out for them. 

3. Not Eating Vegetables

Fiber provides food for the good bacteria in your digestive system. The bacteria, then produce short-chain fatty acids, which support the health of your gut lining.

I’ve met so many people who have developed autoimmune issues and food sensitivities after following a low-carb or ketogenic diet. I believe that most of the time, the cause is the combination of ridiculous amounts of fat and virtually no fiber in their diet. 

Vegetables and organ meats are also your main source of food-based micronutrients on keto. If you’re like most people, you’re probably not eating much for organ meat, so it comes down to vegetables and some berries. While I always recommend a high-quality multivitamin, I also can’t overemphasize the importance of eating plenty of nonstarchy vegetables. 

4. Eating Too Much Fat

Say what?! I thought I got to eat as much fat as I wanted?!

You’re less likely to gain weight on keto when you overeat, but if you eat too much fat, you won’t need to burn body fat for energy. And that’s kind of the point, right? You won’t get fatter, but you probably won’t get leaner either.

Gorging on fat bombs, butter, and drinking pints of heavy cream isn’t going to get you results.

While the ketogenic diet provides a plethora of health benefits, it’s not the fat free-for-all solution that’s the antithesis to the fat-free for all dietary dogma of the past several decades.

5. Neglecting Weight Training

Don’t lose muscle.

That’s one of my mantras whenever I make nutrition, lifestyle, and fitness recommendations.

If you don’t strength train, you will lose muscle. In fact, your rate of muscle loss on keto could be faster than other diets, since you’re more likely to have elevated cortisol, low insulin, compromised sleep, and low growth hormone.

Whether your goal is weight loss or you want to simply stay healthy and fit, weight training is a necessary part of maintaining a healthy body

Beyond that, though, weight training improves insulin sensitivity, increases your capacity to store glucose, and increases testosterone and growth hormone production.

Weight training and walking are the two most important physical activities on a ketogenic diet.

That’s not to say you can’t do cardio, yoga, Pilates, ballroom dancing, or play pickle ball (which is a blast). But, the most important thing you can do is to follow a good, progressive strength training program.

You need to lift weights.

6. Not Getting Enough Electrolytes

Insulin helps you retain sodium. When insulin is low, you excrete more sodium.

You need sodium to work with potassium for normal heart rhythm and muscle contraction. You also need sodium to maintain normal blood pressure.

If you don’t intentionally add salt to your diet while on keto, you might get lightheaded, have low blood pressure, and feel more fatigued than usual.

Drink at least half your body weight in ounces of water each day, but do it Himalayan style — add some pink Himalayan salt to your water bottle. The salt adds sodium to your water, and has dozens of other trace minerals in it.

If you don’t have Himalayan salt, and you’re feeling the effects of low blood pressure, go ahead and use Morton’s or another iodized salt. The paleo police might not condone such behavior, but it’s probably better to keep your blood pressure normal, and get the better salt when you can.

7. Constant Snacking

Whether or not you’re on keto, you need periods of fasting and periods of feeding. 

Growth hormone levels rise about three to four hours after a meal, assuming you don’t snack in the meantime.

A snack is anything that contains calories. 

Learn to experience the feeling of true hunger. Ghrelin, the hormone that makes your stomach growl, is also the hormone that stimulates growth hormone.

Most people don’t need to eat more than three times per day, and you might even do better with two.

That doesn’t mean you can’t eat your favorite keto snack food. Just eat it when you sit down for your meal, not between meals.

8. Comparing Ketones

Too many people get obsessed with measuring their ketone level. They end up eating ridiculous amounts of fat and minimal protein, just to get a higher number on a ketone meter.

The point of being on keto is to improve your health and fitness. It is not to win a blood ketone contest.

9. Overcomplicating Keto

The more complex you make the diet, the less likely it is that you’ll follow through with it.

Eat mostly fats, some protein, some nonstarchy vegetables, very few carbs.

The statement above is overly simplistic. It’s as easy as eating fatty cuts of meat, and adding some butter to your cooked vegetables or olive oil to your salad dressing.

Unfortunately, instead of just going with it as-is, people overcomplicate it. 

For example, rather than just taking “mostly fats” at face value, they keep reading articles and books and end up confused about what “eat mostly fats” even means.

Instead of just eating more fat, they ask more questions and take no action. 

What type of fats do I need to eat? Can I cook with it? Can I add it to my coffee? What time of day should I start eating it? Can I eat the fat with the protein or should it be by itself? Does it have to have a certain amount of omega-3s? Omega-6s? MCTs? What coconut oil is best? What if I buy the wrong brand?

Does my cream need to come from the utter of a grass-fed cow born in New Zealand with exactly two spots on its right side in the shapes of unicorns?

Too far? It was the unicorns that went too far. Sorry. 

The point is, you don’t have to overcomplicate things. Eat food, mostly fat, some protein, some nonstarchy vegetables, and very little carbohydrates. 

It’s OK to have a growing interest in nutrition. It’s interesting! But, don’t let your need to start and make progress become an obsession with doing things perfectly. 

There is no “perfect” when it comes to nutrition. 

If you never read another nutrition book or article, you’d have everything you need right here to successfully use keto to get great results. 

Go to the store, and fill your cart with:

  • Meat, fish, poultry, eggs, whey protein
  • Cheese (if you tolerate dairy), avocado, nuts, heavy cream, coconut oil
  • Fibrous vegetables like leafy greens, broccoli, cauliflower, eggplant, cucumbers, dill pickles

Bring the food home and eat:

  • Eat at least 0.75 grams of protein per pound of ideal body weight, spread out over your meals for the day (that “~” sign means about, not “exactly”).
  • Eat 30 grams or fewer of net carbohydrates each day. 
  • Add enough fat to keep you full, while experiencing weekly weight loss.
  • Don’t snack. 

That’s it. It’s that simple to get started with the nutrition part of keto.

Keto Supplementation

Often, people fall into one of two camps with nutritional supplements.

Either they believe they’re only necessary in special circumstances and that most don’t work, or they buy supplements left and right, hoping they’ll cover up their poor dietary and lifestyle choices. Neither point of view does justice to how supplements work, and why you should include them in your nutrition program.

Consider your core supplements as part of your monthly grocery budget. Just as you need to buy and eat vegetables and protein, you also need to buy and take some high-quality supplements.

If you see supplements as a luxury or something you’d invest in when you get “serious” about your nutrition, you’re seriously missing out.

No supplement is so good that it can undo the effects of a lousy diet. No diet is so good that you can’t benefit from supplementation.

In addition, due to the restrictive nature of a ketogenic diet, you do risk creating some micronutrient deficiencies by relying on food alone.

The following is a starter list of supplements which may help you with your health and fitness goals while doing keto.

The Foundational Five (Start Here)

I can’t stress this enough: Before you buy weight-loss, muscle-gaining, or performance-enhancing supplements, start with the Foundational Five.

Without these five supplements forming the foundation of your nutrition plan, you’ll likely lack some of the micronutrients that support your fat-loss, muscle-gaining, or performance-enhancing goals.

If you’re already using the Foundational Five each day, read on for additional keto-related supplements. If not, start with the Foundational Five first.

  1. High-Quality Multivitamin
  2. Omega-3 Fish Oil
  3. Magnesium
  4. Vitamin D
  5. Digestive Enzymes


Research shows berberine inhibits inflammation, turns on genes involved in raising metabolic rate, turns off genes involved in fat storage, and enhances insulin sensitivity. 

Some studies indicate its effect on blood sugar rivals Metformin.

Supplementing with berberine has been also shown to increase short-chain fatty acid production by gut bacteria, without any change to fiber in the diet. Like fiber, berberine can be especially powerful for gut health. 

With it also supporting insulin sensitivity and normal blood-sugar and cholesterol levels, it’s a perfect supplement for keto.

Medium-Chain Triglycerides

Medium-chain triglycerides, or MCTs, are a specific type of fat that is absorbed through the stomach differently than most other fats.

Most fats require bile, and in excess, can create endotoxins, which increase inflammation. MCTs are absorbed without the need for bile and do not cause endotoxin formation.

As great as that sounds, if you use too much, too quickly, you will get diarrhea. 

Research shows that people might be able to maintain nutritional ketosis without being quite as strict on their diet when supplementing with MCTs. 

Where a typical ketogenic diet includes only about 5 percent of calories from carbohydrate, carbohydrate intake could be tripled, provided enough of the fat came from MCTs. 

The key here, though, is that the MCTs replaced some of the dietary fat to allow that to happen. 

Coconut oil is often marketed as being a rich source of MCTs, but the concentration is very low. You won’t get a therapeutic effect from the coconut oil, and would need to supplement with straight MCTs to get the benefits described in the research. 

If you have any concerns about the amount of fat used in the ketogenic diet, consider swapping a good portion of your daily dietary fat intake with MCT oil. Just take your time in swapping one for another. 

Start with a teaspoon once per day, working up to a teaspoon with each meal, and then increase the amount with each meal.

Why with your meals? Remember the section on snacking under keto mistakes? 

Taking MCTs raises fatty acid levels, like food would. If you want the post-meal growth-hormone secretion, you need to avoid food between meals, so both your blood sugar and fatty acid levels return to baseline, stimulating growth hormone.

If you like them in your morning cup of coffee, be sure to wait for at least four hours afterward to eat your first meal.

Exogenous Ketones

Exogenous means “from outside the body,” which contrasts with endogenous ketones, the ketones your body makes in response to the diet.

Exogenous ketones are supplements that deliver the very same ketones you produce in your body through a supplement form.

Though exogenous ketones have been studied for decades, they’ve only recently become commercially available. The research related to their use is exciting, even for those who may not follow a ketogenic diet. 

Exogenous ketones come in ketone mineral salts and ketone esters. Though the esters seem to work better, they’re very difficult to consume and taste awful.

Research shows exogenous ketones lower blood glucose, whether one is on a ketogenic diet or not. They also decrease free fatty-acid levels in the blood, and may help calm the mind for those with anxiety.

The elevation in blood ketones, following their consumption, causes the liver and muscle cells to take up glucose and fatty acids. 

This is different from nutritional ketosis, which also causes lower blood-sugar levels, but maintains or elevates free fatty-acids levels. 

Also, exogenous ketones may reduce the liver’s production of endogenous ketones. Since the body recognizes that ketone levels are elevated, it may shut down its own production until the exogenous ketones are used up.

Exogenous ketones do not cause ketosis. Rather they mimic some of the effects of being in nutritional ketosis.

Because the exogenous ketones cause a drop in blood sugar, those who are not on a ketogenic diet, but use ketones, may notice the drop in blood sugar more than those who already have lower blood-sugar levels. 

If you’re on medication to manage blood sugar, connect with your doctor before using exogenous ketones, and monitor your blood-sugar levels closely.

Because cortisol rises when blood sugar drops, cortisol levels have been shown to increase after supplementing with exogenous ketones.

For most people, it’s probably not an issue and would be a short-term effect, but in the small percentage of people who have chronically elevated cortisol, it is something to at least be aware of.

If you react quickly to the ketones, the drop in blood sugar could make you feel jittery, raise your heart rate, or cause some other temporary stress response. This is more likely to happen if you’re not following a ketogenic diet and use the ketones, than if you’re already keeping blood-sugar levels low.

One other word of caution for those with high blood pressure: Exogenous ketones today are often made by combining the ketone to sodium, so your sodium intake would increase quite a bit with their use. If you use exogenous ketones, then you probably don’t need to worry about salting your water, like I discussed about above.

If you’re being treated by a doctor for high blood pressure, be sure to consult him or her before making significant changes to your diet or supplement plan. 

Exogenous ketone supplementation is an exciting area of research and there’s still much to be learned. At this point, research shows they provide a unique dietary advantage in that you can experience the benefits of ketones without necessarily being on a ketogenic diet. 

However, your health and fitness are surely to improve more from using exogenous ketones with a low-carb or ketogenic diet rather than simply using the exogenous ketones as dietary supplements with a western diet.

Whether the exogenous ketones enhance physical performance remains to be seen.  Muscle cells are less effective than other tissues at ketone uptake. 

At low levels of ketosis, up to half of the ketones are taken up by muscle, but as ketone levels rise, muscle uptake drops to as little as 5 percent of ketone availability. It seems muscle cells get saturated quickly.

So, with all that being said, if you have a friend hounding you to buy their ketone supplements and their health claims sound too good to be true, they very well could be.

What Do You Do After Keto?

As fascinating and buzz-worthy as the ketogenic diet is, there’s still more unknown about the long-term influence of carbohydrate restriction than is known.

Committing to one way of eating is far more difficult mentally than physically. 

To convince themselves that the diet they’re on is the right one to follow, people often paint the picture of their diet as the hero and all others as the villains. 

They start to speak of the foods that fit into their nutrition plan as though they’re delivered by the hand of God, and the foods that don’t fit in the plan as though they came from the devil. 

I was guilty of this myself as a younger fitness professional.

Carbs are not evil. Sugar is not poison. 

I need to emphasize this because, as compelling as keto is for dealing with disease and even for improving health in the short-term, nobody knows what the long-term effects of avoiding one of the three macronutrients will be.

I believe we can benefit from carbs when they’re not eaten at every meal or in excess. That includes some sugar, too.

Excessive carbohydrate consumption contributes to insulin resistance, obesity, diabetes, and many of the neurodegenerative diseases linked to all of this are tied to carbohydrate intolerance. 

When you spend too much time in the sun, you get burned. When you overdo carbohydrates, you do damage, too.

But, in the right doses, sun exposure is critical for your health. The same could be said about carbohydrates.


Keep the conversation going.

Leave a comment, ask a question, or see what others are talking about in the Life Time Health Facebook group.

The Life Time Health Team

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