Sections in this article:
- Why is weight a common measure of health?
- How have ideas about healthy weight varied over time and across cultures?
- What sort of health problems can a “weight-normative” approach that privileges low body weights produce?
- How important is weight compared with other health markers?
- Why do my health markers improve when I lose weight?
- Is it possible to be fit and strong while having a high body weight?
- What are some better measures of genuine health?
On almost any trip to the doctor’s office, the first measurement is taken right there in the clinic hallway — on the scale. Others follow in the privacy of the exam room and lab, but that first one is prominent, prompt, and public. The nurse scribbles your weight on your chart like a grade, often before you even have a chance to say why you’re there.
There’s no doubt about it — in the world of healthcare, weight is given . . . a lot of weight.
But how important is that number really?
Media headlines and the medical establishment alike tend to conflate fatness with sickness. Alarms sound about the rising number of people who qualify as overweight or obese, and the presumed implications for public health.
Yet research suggests that the relationship between heaviness and disease is more complicated and less direct than we’ve been led to believe. In fact, the notion that weight is a reliable predictor of health and fitness appears to be simply incorrect.
Instead, what counts as a healthy body size is likely to be highly individual, and well-being is better gauged by measures not found on a scale, including good labs, stress levels, sleep, movement, and a positive relationship with food.
Indeed, a chart definition of health based on weight may cause more problems than it solves.
Why is weight a common measure of health in the medical community?
Public-health officials use body mass index (BMI) to classify people as underweight, normal weight, overweight, or obese, based on a simple equation — a person’s weight in kilograms divided by the square of their height in meters.
A BMI between 18.5 and 24.9 is considered “normal or healthy weight” for adult men and women, while a score of 25 to 29.9 is “overweight,” and anything over 30 is ruled “obese.”
But even the Centers for Disease Control and Prevention acknowledges that BMI alone is “not diagnostic of the body fatness or health of an individual.”
The BMI equation doesn’t differentiate between muscle and body fat, for starters, so a muscular athlete can easily have a BMI over 30. (According to the BMI scale, shown below, Dwayne “The Rock” Johnson qualifies as “obese.”)
And because the equation was developed using Western European bodies to determine averages, BMI has been shown to overestimate obesity in Black people; at the same BMI, Black people typically have less overall body fat than white people, according to research cited by the CDC.
What’s more, a 2013 study published in JAMA found no linear relationship between BMI and risk of premature death. Rather, researchers described a U-shaped curve, with the lowest risk of death for those in the “overweight” category (around 25 to 26 BMI).
People considered “mildly obese” had about the same risk of dying prematurely as those in the “normal” category. Death rates rose (slightly) at either end of the curve, for those considered underweight or obese.
“It’s unfortunate that BMI has become a common measure of health.”
Still, despite its limitations as a diagnostic tool, BMI is measured on almost any trip to the doctor’s office.
“It’s unfortunate that BMI has become a common measure of health,” says Dana Magee, RD, LD, a weight-inclusive nutrition coach in Annapolis, Md., noting that the index was originally intended for analysis at the population level, not to offer insight into an individual’s health. (It was introduced by Belgian mathematician Adolphe Quetelet in the 19th century as a way to gauge obesity rates across the general population.)
“Now every doctor’s-office printout mentions it, and it takes the focus off important things and puts it on something that doesn’t have a direct link to health,” says Magee.
Body-fat percentage may provide slightly more insight than BMI because it accounts for muscle and bone mass in its measurements. But according to Jennifer Campbell, MS, a nutrition and behavior-change coach based in British Columbia, it still fails to take into account that different kinds of fat — such as visceral abdominal fat versus subcutaneous fat throughout the body — may have different implications for health. Fat cells in the abdomen, for instance, can release molecules that contribute to systemic inflammation and insulin resistance, unlike more evenly distributed subcutaneous fat.
And measuring body-fat percentage still suggests that fat or body size in excess of what’s on a chart is automatically a health problem.
“All these different ways of measuring body size completely ignore emotional, mental, and social health,” notes Campbell.
So why does the medical establishment still rely on body-size measurements as critical indicators of someone’s overall health status?
“Weight is such an easy thing to measure,” says Sandra Aamodt, PhD, author of Why Diets Make Us Fat. “Most other more-indicative measures require blood tests or fasting first, so they’re much less convenient than weight. Weight is only a correlate of some of these more useful tests — and not a fantastic one at that — but it’s very easy to get.”
How have ideas about healthy weight varied over time and across cultures?
Some cultures and communities have historically associated larger, more robust builds with increased vigor and health.
Even the seemingly static numbers on the BMI chart have been reclassified and reinterpreted over time. Before 1998, the “normal” weight category ranged from 18.5 to 27.3 for women (27.8 for men).
The categories were revised downward in 1998 after a committee convened by the National Institutes of Health concluded — based on shaky data — that death rates increased as body mass surpassed 25. Overnight, some 29 million Americans were newly classified as overweight, without any change in their bodies.
What sort of health problems can a “weight-normative” approach that privileges low body weights produce?
“The most problematic effect of the weight-normative approach is stigma,” says Ander Wilson, MS, RDN, LDN, a dietitian and cofounder of Nashville Nutrition Partners.
“Whenever someone is shamed or their other symptoms are dismissed because of their weight, it leads to missed diagnoses,” she says.
“Conversations during appointments are often full of weight shaming. This experience can trigger an increased stress response in a person’s body and can lead to something called healthcare avoidance. This means these people are less likely to seek medical care in the future.”
“Whenever someone is shamed or their other symptoms are dismissed because of their weight, it leads to missed diagnoses.”
Wilson recalls a client who came to her with low energy and recent weight gain. Her doctor had told her to lose weight by not eating for a few days every week, and she had tried, but she ended up gaining weight and feeling totally exhausted.
“It turns out her exhaustion was caused by a serious condition that required immediate biopsy and then surgery,” says Wilson. “That had been totally missed because of the focus on her weight.”
On the flip side, she notes that unexplained weight loss can often indicate the presence of a serious medical condition, such as type 1 diabetes. “Rather than investigating weight loss as a possible symptom, it’s often praised — when that person needs life-saving insulin. So that weight stigma goes both ways.”
And it isn’t limited to doctors’ offices. Even the most well-meaning among us may inadvertently assume that larger bodies are unhealthy, especially if we’re looking in the mirror. But that perception itself may cause health problems.
“Weight stigma contributes to disease,” explains Lindo Bacon, PhD, author of Health at Every Size. “It acts on us biologically, increasing cortisol and vulnerability to things like diabetes and heart disease. The emotional response to weight stigma mediates a physical response. As long as we think of weight as a problem and weight loss as a healthy solution, we’re losing sight of what’s important.”
As mentioned, the extreme focus on weight as a barometer of health can also lead to yo-yo dieting, or weight cycling, in which people restrict their diets to try to lose weight at the urging of a healthcare provider — and almost always gain it back in the long term. Not only do the vast majority of people who lose weight by dieting fail to keep it off for more than a couple of years, a 2007 metastudy in American Psychologist noted that one-third to two-thirds of dieters regained more weight than they had lost.
“If you weight-cycle frequently, it sets your body up to protect against future weight loss,” explains Bacon. “One of the side effects of weight cycling is higher weights in the long run.”
Aamodt notes several reasons for people’s inability to maintain significant weight loss over time, including a complex energy-balance system that our bodies use to defend a given weight set point through thermogenesis, resting metabolic rate, and hunger-regulating hormones, such as leptin.
“We know that people who lose weight are likely to gain it back. We have as much research evidence to predict that outcome as we do for smoking causing cancer,” says Wilson.
And setting people up to weight-cycle can lead to more numerous and problematic health issues than they were facing in the first place, including disordered eating, which often causes gastrointestinal problems that persist even after recovery (such as gastroparesis, a disorder involving hindered stomach function).
“It’s clear the risk of disordered eating goes up the more often someone has dieted,” says Aamodt, noting that there’s a wide spectrum of disordered eating, not all of which qualifies for official diagnosis. “It can be a full-time job mentally for people who constantly think about what they could eat, should eat, shouldn’t eat, might eat.”
When Magee starts working with new clients, she asks them to rate the amount of energy they spend thinking about food and diet on a scale of 1 to 10. “Very often the score is high — sometimes even off the charts at an 11 or 12,” says Magee. “People forget that our brains are part of our whole body. If something is hurting our mental health, it’s not improving our overall health.”
Binge-eating disorder (BED), the most common eating disorder in the United States, is marked by recurring episodes of eating large amounts of food, usually quickly, followed by feelings of shame, guilt, and remorse. A history of significant weight changes and a preoccupation with losing weight can be risk factors for BED.
The condition can also be exacerbated by dieting and caloric restriction, because deprivation sets up the brain and body to swing in the other direction.
Weight cycling has other consequences for physical health as well, including increased risk of stroke and heart attack and changes in the way the body regulates body fat. Rapid weight loss usually involves a combination of muscle and fat, while rebound weight gain is mostly fat.
And yet the weight-normative approach to health persists. “If healthcare providers had five interventions to choose from, we’d usually start with the one with the fewest side effects and best outcomes,” says Wilson. “But weight loss is still widely recommended, even though it is often the most ineffective and unsuccessful intervention.
“The bias against larger bodies is not based on health,” she explains, “and we have to unpack that because it gets in the way of people getting proper healthcare, diagnoses, and treatment.”
How important is weight compared with other health markers?
“It’s not even in the top five most important markers of health,” says Aamodt, noting that poverty, loneliness, fitness level, blood pressure, and smoking are all more predictive of someone’s health status than their weight.
“Someone’s measured fitness level — their ability to do a certain amount of exercise — is much better correlated with health than weight,” she explains. “Statistically, thinner people tend to be more fit, but that’s only a correlation. If you relied on weight to predict someone’s health, you’d get 30 to 40 percent of your guesses wrong.”
If you had access to only one number to gauge someone’s health, blood pressure would offer the most insight, followed by blood glucose and cholesterol, Aamodt says. “The stuff your doctor checks every few years in routine blood work? Those are really quite predictive,” she continues, adding that you can’t anticipate those numbers based on someone’s weight. “Many people eat well and exercise a lot and still weigh more than their doctors think they should.”
Just as there’s no evidence to support an assumption that someone with a larger body is unwell, equating thinness with health can also be misleading.
Just as there’s no evidence to support an assumption that someone with a larger body is unwell, equating thinness with health can also be misleading, says Magee. “A thin person may not be eating well, managing stress, sleeping well, or exercising, and we label them as healthy even though there’s no evidence of that other than what they look like on the outside.”
Two people can be the exact same height and weight but practice very different lifestyle behaviors, notes Lucia Hawley, FNTP, MSW, a nutrition coach based in Portland, Ore. Hawley recommends a DUTCH (Dried Urine Test for Comprehensive Hormones) assessment as one source of valuable insight for overall health.
“Looking at hormones will tell you if you’re stressed the heck out,” she notes, adding that a full thyroid panel can also be highly informative.
“Body weight is really just one piece of the picture of someone’s health,” says Hawley. “Insulin sensitivity, inflammatory markers like C-reactive protein, and cholesterol levels can be canaries in the coal mine, showing that the body is in chronic stress mode.”
“As a measure, weight doesn’t tell us a whole lot,” says Wilson. “Chasing weight loss is a distraction.”
Why do my health markers improve when I lose weight? And isn’t higher body weight a risk factor for certain diseases, like type 2 diabetes?
“There’s a lot of literature that shows when people go on diets, their health markers improve,” acknowledges Aamodt. “It seems clear that it’s almost always because people are exercising more and eating more veggies and less junk food. Those things are good for you, but they don’t necessarily act through weight loss.”
It’s true that obesity is associated with higher disease and mortality risk, but Aamodt says the evidence suggests that’s because the same factors that lead to type 2 diabetes and heart attacks — such as metabolic syndrome — also increase the odds of obesity. It’s a matter of correlation, not causation.
“Blaming fatness for heart disease is similar to blaming yellow teeth for lung cancer,” says Bacon, “rather than considering that smoking might play a role in both.”
Traci Mann, PhD, is a professor and researcher who directs a lab that studies health and eating behaviors at the University of Minnesota. In a 2013 study, she examined the correlation between the amount of weight people lost and their overall health improvements; she found no connection.
“People on diets did improve their health regardless of whether they lost weight or how much they lost,” explains Aamodt. The researchers concluded that improved eating and exercise habits led to health improvements, but weight loss was not the driving mechanism.
Both exercise and diets rich in vegetables and fruits are known to lower inflammation, improve sleep, and bolster the health of the microbiome. This in turn can benefit mental health, the immune system, and digestion — all worthy goals in themselves. “Weight loss is a correlate that we’ve been taught to focus on, even though it’s not the part that matters,” says Aamodt.
But if someone has been conditioned to view weight loss as the only evidence of success, they may abandon lifestyle changes that are making a real difference to the health markers that actually matter, such as blood pressure, cholesterol, and fitness level.
Conversely, they may justify unhealthy behaviors, such as excessive food restriction or compulsive exercise, in the name of weight loss. “Any goal you’re pursuing should be through healthy behavior change,” notes Campbell. “Anytime you have to use unhealthy behaviors to achieve weight loss, that’s not in the service of health.”
As for the correlation between weight gain and type 2 diabetes, Wilson notes that it’s still unclear which comes first. “Diabetes is marked by insulin resistance, which can cause weight gain,” she explains. Focusing on weight loss as a way to address type 2 diabetes may be akin to fixing the smoker’s yellow teeth (from Bacon’s analogy) as a way to address the health risks of smoking.
Wilson uses the example of polycystic ovarian syndrome, or PCOS, which may cause women to gain weight as a result of elevated circulating insulin. If they try to lose weight without addressing the underlying cause, their bodies will fight that weight loss — and the stress can cause insulin levels to rise even higher, exacerbating the problem.
That’s why she recommends looking beyond weight loss and instead directly addressing modifiable risk factors for disease with healthy and sustainable lifestyle approaches.
Is it possible to be fit and strong while having a high body weight?
Yes! Strength and fitness are almost entirely independent of body size, and there are plenty of reasons to pursue them that have nothing to do with weight loss.
“Movement triggers tremendous changes in your musculoskeletal and cardiovascular systems and in the hormones and neurotransmitters involved in health, such as the all-important relaxation response,” write Bacon and coauthor Lucy Aphramor, PhD, RD, in Body Respect. They note that exercise helps to increase energy, improve sleep, enhance mood, and confer a sense of overall well-being.
A 2014 study in European Endocrinology showed that “obese” people who are at least moderately fit have a lower mortality risk than those who are “normal” weight but unfit. This means that fitness is a better predictor of health than weight — and the two do not necessarily go hand-in-hand.
The same researchers found that improving cardiorespiratory fitness plays a bigger role than weight loss in protecting individuals with type 2 diabetes from cardiovascular disease.
What are some better measures of genuine health?
There are myriad ways to measure health that have little or nothing to do with weight, including emotional resilience, mental health, regular menstrual cycles for those who menstruate, and good labs.
“The most common metrics of wellness should include movement, sleep, stress, quality of relationships, and mental health,” says Wilson, adding that it’s important for people to decide for themselves what thriving looks and feels like.
While objective measures like lab tests or fitness goals can help identify imbalances or provide a sense of accomplishment, health is ultimately about tapping into your own intuition and trusting your body to tell you what it needs in terms of nutrition, movement, and social connection.
If someone has been outsourcing their intuition about their diet or health for too long, it can be helpful to work with a Health at Every Size provider or dietitian, adds Wilson. (Find one online at www.haescommunity.com/search.)
“It all comes back to individual experience and what someone wants for their life,” says Hawley. She notes that working with a functional-medicine provider can help you consider lab numbers or health goals within the broader context of your physical, social, and spiritual health — all things that a single-minded focus on weight can harm or obscure.
Finally, remember that the most important measure of health is how you feel. “Map out what makes up your total well-being,” Wilson advises. “Give yourself permission for it to be different from your friend or neighbor. No one knows what feels good in your body as much as you do.”
The BMI Standards
The below chart is used by health professionals to link weight to health, but its many inadequacies include an inability to differentiate between muscle and adipose tissue.
|30.0 and above