We’re a society obsessed with weight. It’s no wonder the weight loss industry was estimated to be worth $142.6 billion in 2022. And it’s expected to more than double by 2030. This isn’t surprising when you realize most diet programs, many foods, the fitness industry and social media influencers promote weight loss to improve health. And you’ve probably been weighed by your doctor at some point. It would be easy to think that you weight is a measure of your health. But that’s not really true. So, what does your weight tell you?
Your Weight and Your Health
Yes, your weight can be affected by your health. And your health can be affected by your weight. But that doesn’t mean we can tell if someone is healthy or not by their weight. Your body weight is a combination of your bones, muscle and fat. And it’s really the amount of fat that’s of concern, and to some extent muscle. Excess body fat is associated with a greater chance of many diseases such as type 2 diabetes, heart disease and some cancers, as well as a shorter lifespan. Muscle, or a lack therefore, is also associated with disease and shorter lifespan, primarily in older adults.
In the doctor’s office, weight is converted into the body mass index (BMI), a function of weight over height. And from there, we have BMI categories of underweight, normal, overweight and obese. People whose BMI falls within the overweight and obese categories may be at increased risk for disease, likewise with being underweight.
But a single weight measure, and BMI by extension, isn’t much help. Whether you’re 170 pounds or 185 pounds doesn’t tell me if you’re healthy or not. Sure, if you take 1000 people and calculate their BMI, those people with higher weight and BMI values generally have more body fat. This is helpful to know when we’re dealing with populations, but when it comes to individuals, it’s not so great. This goes back to weight, and BMI, not distinguishing between bone, fat and muscle.
Can you be healthy at any weight or BMI?
To some extent yes. Of course it depends on what your definition of health is, but there are plenty of examples in which people classified as overweight or having obesity are considered healthy. Some examples are body builders and heavyweight boxers, who based on their BMI would be considered to have clinical obesity. But the excess weight is not due to fat, rather it’s from a lot of muscle.
Some studies even show that people in the overweight BMI category have the longest lifespan. But many of these studies were done with a single measure of BMI, which doesn’t reflect if someone’s weight was previously higher or lower. When BMI from earlier years was considered, people who were previously overweight or had obesity, but considered normal weight at the time of the study, had worse health than those who were in the normal category all along.
There are also plenty of people who are of ideal or normal BMI who are not healthy. One study found nearly 1/3 of overweight people to be healthy based on their risk factors (blood pressure, blood sugar and cholesterol), while a third of normal weight people had worse risk factors. Now risk factors only capture one aspect of health and people with excess fat may also be at risk for joint pain, psychological distress and discrimination. Together, these examples highlight the problems with looking at weight and BMI alone.
Location Matters
Another problem is your weight doesn’t tell you where your fat is located. That may be apparent by looking in the mirror or how your clothes fit. Because, when it comes to body fat, it’s just like real estate, location, location, location. Fat around your waist is associated with higher risk factors and greater chances for disease than fat elsewhere.
This is because the type of fat and fat cells that sit around our waist are different. These fat cells are more active and can lead to problems with insulin and fat metabolism. That person who may have a normal BMI could still have an elevated waist and be at greater risk for disease than someone who is overweight but their body fat is around their hips and have a slim waist.
Why do doctors weigh their patients?
Doctors at times may calculate your BMI and compare that to the BMI categories to get a sense of your risk for disease. Even though there are many problems with BMI, it’s still used because it’s easier than other measures of body fat. At the same time, your doctor may measure your blood pressure and do a blood test to assess your blood glucose and cholesterol levels. Once your doctor has those measures, knowing your weight doesn’t really add anything to informing how you’ll be medically treated.
Another reason for weighing is to get a starting, or baseline, measure for future weight/BMI measures. While weight measures more than just fat, for most adults, a change in weight is usually due to a change in fat. In that case, it may help get a sense as to whether someone’s health risk is going up or down, but again, it won’t tell you where the fat is put on or taken off. And it won’t tell you if you’re healthy or not.
A number of doctors are turning away from measuring their patients’ weight. In part, because weight and BMI aren’t very informative. But also, because a focus on a patient’s weight can distract from providing the best medical care. The American Medical Association and the Canadian Clinical Practice Guidelines for Obesity are recommending doctors look beyond the BMI and focus on healthy living regardless of body size. And the Association for Size Diversity in Health advocates for a Healthy at Any Size principle to move away form the potential for size discrimination that may occur in healthcare.
When should you weigh yourself?
There are definitely some instances in which you may wish to weigh yourself or a doctor may recommend it. For people with heart or kidney failure, weighing daily is part of good self-care. This is because an increase in weight may be the result of fluid (water) retention, which may reflect that the heart or kidney is getting weaker.
It may also be good to weigh yourself if you think you have experienced any unintentional weight loss. Losing weight without meaning to can be an indication of an illness. If that happens, it’s good to consult your doctor.
Lastly, you may wish to weigh yourself if you are involved in a weight loss program. There are studies that show people who weigh themselves regularly are more successful at weight loss. In these cases, it may provide accountability and feedback on one’s lifestyle. However, always be aware that your body weight does not define how healthy you are. Taking stock of your lifestyle (nutrition, activity, sleep patterns, etc.) will do more to tell you about your health than weight or BMI.
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