Do you ever step on the scale and feel like the number doesn’t actually reveal much about your body or your health? Well, you’re right. Despite all the emphasis on body weight, the truth is, it doesn’t tell the full story. Body weight is just one potential indicator of a person’s health. As a physician, I rely on a wide variety of factors to get a clear picture of my patients’ overall health and what diseases they may be most at risk for. This includes patient history, lab work and even body composition. In my own personal and professional experience, body composition is a much better indicator of a person’s health risk than is body weight or body mass index (BMI).
What Is Body Composition Testing?
Body composition is a method of describing what the body is made of, including fat, protein, minerals, and water. With body composition testing, we get good insight on a person’s specific muscle and body fat levels. This is important because body fat percentage tells us a lot more about risk for certain diseases, such as diabetes and heart disease, than does body weight. For example, a 200-pound professional athlete might have a lean, 12 percent body fat, while a 200-pound sedentary office worker of the same height might have 32 percent body fat. Their height and weight are the same, but who do you think is more likely to be at risk for heart disease or diabetes? The person with the higher percent body fat.
Why Scales and BMI Can Fall Short
BMI is a measure of body fat based on your weight in relation to your height. BMI is a quick and easy measurement that can help screen for weight categories associated with health problems, but let me clear: it shouldn’t be used to diagnose the body fatness or overall health of a person. There are a number of variables that can influence the interpretation of BMI. Here are just a few that I consider when interpreting my patients’ BMIs:
- Muscle mass: Muscular people and highly-trained athletes may have a high BMI because of their increased muscle mass. Their weight on the scale may make it appear as if they are overweight, but because their weight is attributed largely to their muscle mass, they typically will not have the same disease risk as those with higher body fat percentages.
- Ethnicity: Some ethnic populations tend to have low BMIs and higher body fat percentages compared to other ethnic populations. While they may look “thin,” research shows they may have a higher prevalence of heart disease compared to their counterparts with less body fat (1).
- Age and Gender: In general, older adults tend to have more body fat than younger adults who have an equivalent BMI. Women also tend to have more body fat than men of a similar BMI.
All these factors, and more, need to be considered when predicting health outcomes.
What Does Body Composition Reveal?
One of the main components we’re looking at with body composition testing is a person’s percent body fat. Research has shown that an individual’s body fat percentage is a significantly better indicator of their risk for heart disease than their BMI (2). It’s also not just about the overall percentage, but where the fat is located. People who have increased fat in the abdominal region tend to be at greater risk of diseases including hypertension, gall bladder disease, cardiovascular disease and diabetes compared to people who tend to store fat in other areas of their body (3).
How to Test Body Composition
There are several methods of body composition testing including: skinfold calipers, hydrostatic weighing (underwater weighing), dual energy x-ray absorptiometry (DEXA) and bioelectric impedance analysis (BIA). I recommend BIA to most of my patients, based on the ease and accuracy of this test. BIA works by sending a small electrical current into the body and measuring how it travels throughout the body. In addition to revealing your body fat percentage, some BIA devices can also report water weight, skeletal muscle mass, lean body mass and more.
Changing Your Body Composition
The important thing to remember is that you have the ability to directly change your own body composition through diet and exercise. It isn’t about how you look, but rather the impact that it can have on your health. Research shows that even small decreases in body fat can result in improved insulin sensitivity and your body’s ability to manage glucose. (4, 5). There are many ways to change your body composition, such as reducing your calorie intake, increasing your caloric burn through exercise, and adopting a weight-lifting routine to help build muscle mass. Additionally, enjoying smaller meals more frequently may be another helpful strategy. One research review of 15 studies concluded that eating small, frequent meals enhances fat loss, as well as increases in fat-free mass (i.e. muscle) (6).
While the scale can certainly help you track changes in your body weight, a better indicator of health is your body composition. Not only are body composition measurements more specific than body weight, they are also more directly tied to your likelihood of preventing or reducing chronic diseases such as diabetes and heart disease. While your body type is determined, in part, by genetics, have the power to change your body composition. A thoughtful eating and exercise plan will not only yield positive changes to your waistline, but also to your body’s overall health.