ASK THE DOCTOR: The Pros and Cons of the Keto Diet

The ketogenic diet is all the rage right now, but is it right for you? We asked one of our favorite functional-medicine docs, and here’s what she had to say.

By Tiffany Lester, MD | Experience LifeMarch 7, 2019

Ketogenic diets — which are high in fat and very low in carbohydrates — have been the talk of the nutrition world for the past few years. New research has come out about the negative health effects of carbs in regard to increasing obesity rates, and many studies have found that a higher-fat diet may actually be more protective against heart disease than many medical professionals previously thought. A keto diet may sound like a good idea when one is searching for a personalized nutrition plan, but is it right for you?

What Exactly Is a Keto Diet?

A ketogenic diet is when you eliminate carbohydrates entirely or eat a very low-carb diet; the main macronutrient is dietary fat, usually 70 to 75 percent of total calories. The rest of the diet is broken down into 20 to 25 percent protein and 5 percent carbohydrates. On the keto diet, a typical breakfast might be an egg over a bed of leafy greens with 3 tablespoons of olive oil, half an avocado, and a quarter-cup blueberries. Lunch or dinner might be roasted salmon, an arugula salad with olive oil and almond slivers, and avocado.

It sounds extreme and counterintuitive to a balanced, healthy way of eating, but the goal of a keto diet is to get into a state of ketosis. Ketosis is when the body is burning fat stores instead of glucose stores. When we consume carbohydrates, they are converted into glucose. In response, our blood sugar rises and insulin is released from our pancreas. Insulin is a fat-storage hormone, and excess amounts of glucose are stored as fat: This is one of the reasons we gain weight. Cutting carbs and increasing fat intake, on the other hand, supports weight loss because it encourages the body to enter a state of ketosis and start using fat as fuel.

The diet was originally designed in the 1920s by physicians as a way to treat epilepsy. More recently, some oncologists have used the diet to starve cancerous cells that reportedly thrive on sugar. Most of the individuals I recommend it for in my practice are struggling with weight loss or poor blood-sugar control. Others simply want to optimize their lean body mass. Studies have shown that this diet is effective not only for losing weight but for maintaining an ideal weight as well.

So, Is It Right for You?

The answer is maybe. The keto diet has produced promising results for cancer and weight loss, but it is very hard to maintain for an extended period. You can purchase ketone urine strips from the drugstore to see if you are in a ketogenic state, but most people have a hard time cutting back enough on carbs to get there. It is also questionable whether this diet is safe long term —there are concerns that it can lead to kidney issues, for example.

For most individuals, it’s safe to try a ketogenic diet for four to six weeks. But you also have to take into consideration your activity levels. If you are a person who engages in regular intense exercise, you may need to eat a slightly higher percentage of carbs on those days. This can vary from person to person. You should only try a keto diet under the supervision and guidance of a knowledgeable medical provider.

Side effects like bad breath, insomnia, and daytime fatigue may occur throughout the diet. There is also what is known as the ketogenic “flu,” which typically occurs the first week. It almost feels like a withdrawal as your body learns not to use carbohydrates as fuel. During this time symptoms like nausea, dizziness, difficulty focusing, achy muscles, and irritable mood are common. Once you make it over that hump, though, most people feel energized and more alert. While the ketogenic flu doesn’t affect everyone, it is important to be aware of. If it does affect you, drinking fluids like bone broth and adding electrolytes can help decrease symptoms.

Monitoring Your Biomarkers

For patients on a keto diet, I regularly monitor specific biomarkers for patients to track progress as well as to identify any harmful metabolic changes. This is key to ensure there is no long-term damage to the thyroid and sex hormones in particular. Women need to be especially mindful. Our thyroid hormone helps to regulate our metabolism. Eating a ketogenic diet can inhibit the conversion of T4 to T3 (active thyroid hormone), leading to subclinical or worsening hypothyroidism. Women are more likely than men to be diagnosed with autoimmune conditions like hypothyroidism and should have their labs closely monitored by a physician.

The biomarkers I track in my patients on ketogenic diets usually include:

Comprehensive metabolic panel
Complete cholesterol profile
Thyroid hormones (TSH, FT4, FT3)
Sex hormones (estrogen, progesterone, testosterone)

Tools to Track Progress

Outside of ketone urine strips, technology can be an exceptional tool in tracking your progress and diet. My favorite apps are listed below:

8Fit: A membership-based app with custom meal plans and HIIT workouts you can do at home or on the road.
MyFitnessPal: Expansive database that allows you to keep track of your macronutrients in an easy-to-use format that you can share with your doctor or nutritionist.
Senza: Easy-to-make recipes and daily inspirational tips.

This article has been updated. It was originally published on April 2, 2018.

Tiffany Lester, MD is an integrative-medicine doctor, farmacy foodie, and curly girl who believes we all have the ability to take charge of our health. She is Medical Director of Parsley Health in San Francisco, Calif., and she is passionate about healing chronic disease through whole foods and teaching people how simple, small shifts can have an enormous impact on their fatigue, stress, and pain levels. You can find her at www.drtiffanylester.com.

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