Ask the Doctors

Dear Doctor: I'm not thin by any means, but I'm not obese either. I lift weights three to four times a week, run about 10 miles a week, play soccer and regularly do half-marathons. Now a new study says that because my BMI is 26, there's no way I can be fit and healthy. Is this true?

Dear Reader: Due in part to the limitations of BMI as a measurement, many athletes and muscular individuals will fall into the overweight category, which is a body mass index in the range of 25 to 30. The body mass index, a measure of body fat based on the ratio between an individual's height and weight, can be a useful tool. However, it doesn't leave room for additional factors like bone density, muscle mass, overall body composition, or the natural variations inherent in the sex, age or ethnicity of an individual.

For example, the BMI of someone who is athletic can skew higher because of the presence of additional muscle, which is denser than fat. Elderly adults tend to have more body fat than younger adults and may have experienced bone loss as well. And on average, women tend to have a higher percentage of body fat than do men.

With athletic individuals, whose habits when it comes to healthful diet and regular exercise are usually quite good, we tend not to worry that much about their actual weight. In these specific cases, we agree that it is possible to fall into the category of being overweight but still be fit.

However, when a patient edges into the upper regions of the BMI category of overweight, or when they register as obese, which is a body mass index of 30 and above, it becomes a different story. At that point we will definitely explain to them the not-insignificant health risks associated with obesity, no matter how physically active the individual may be. These include high blood pressure, heart disease, stroke, kidney disease, Type 2 diabetes, fatty liver disease, metabolic syndrome and certain cancers.

In a large-scale study published last year in the Journal of the American College of Cardiology, researchers from England found that, even when they were otherwise clinically healthy -- that is, their blood pressure, blood sugar and blood lipid levels were all within the normal range -- individuals who were obese were at measurably higher risk of the adverse health outcomes we mentioned above. Even being overweight raised the risk of coronary heart disease up to 30 percent, despite good blood pressure, blood sugar and blood lipid numbers, according to the study results.

The researchers' conclusions came from analysis of data drawn from the electronic medical records of 3.5 million people between 1995 and 2015. However, critics of the study point out that important factors associated with lifestyle, such as exercise habits, diet or stress, each of which can affect or even skew results, were not given equal weight. (Sorry, but we can't pass up an easy pun.)

If the extra pounds that tipped your BMI into the overweight category can be attributed to additional muscle mass because of your athletic endeavors, and if your metabolic markers are all in good order, then in our opinion, you can consider yourself to be fit.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

More like Ask the Doctors