Body Mass Index (BMI)
Approximately 35% of Americans have elevated BMI, primarily due to inappropriate lifestyle choices.
BMI is a simple way to gauge weight and should be taken seriously by the patient.
- The table to the right is a convenient way to determine BMI.
- People with BMI above 25 experience higher levels of heart disease, diabetes, high blood pressure, osteoarthritis, stroke, cancer, sleep apnea, back pain, lack of vigor, erectile dysfunction and possibly dementia.
- BMI was designed for group studies and is not completely accurate for some individuals.
- BMI tends to be less accurate for short people, tall people and athletic people.
- Women and men are measured on the same BMI scale although they often have different body types.
- As Dr. Steve discusses below, BMI results are more meaningful when considered along with waist measurement.
Olumia Life is a doctor-designed mobile app that makes better eating, fitness and sleep achievable.
by Dr. Steven
Body Mass Index (also called BMI) is a simple and widely used method of determining overall metabolic health. BMI was originally developed for group studies and while it is a fairly reliable indicator of body fat for most people, it is not always accurate. As I discuss below, patients who rank above 25 on the BMI scale should verify the diagnosis by checking their waist size. If both BMI and waist size are elevated, there is almost certainly a problem that should be dealt with.
It’s beyond dispute that for adults, on the whole, health deteriorates as BMI rises above 25. There is a list of studies a mile long documenting this.
BMI alone, however, does not take into account the shape of an individual’s body. So, if a person has a higher than normal amount of muscle, a BMI measurement will assume that the person’s extra weight is fat, not muscle, and the BMI will be the same. For example, if a person starts exercising to lose weight and loses 3 pounds of fat while gaining three pounds of muscle, the BMI will not change. As of 2016, most organizations still use the same BMI scale for both men and women even though their differing body types would indicate different BMI measuring scales.
But the most significant problem with BMI assessments is they do not take into account where body fat is located.
The Role of Body Fat
The location of fat in the body is often a better indicator of disease risk than the amount of fat. Fat that accumulates around the waist and chest, referred to as “abdominal fat” or “visceral fat”, is metabolically active. It releases fatty acids, inflammatory agents and hormones that ultimately lead to higher LDL cholesterol, triglycerides, blood glucose and blood pressure. People who carry excess weight in their hips or thighs, and not their abdomens, are thought to be at less risk of disease and early death than those with excess belly fat.
In the Nurses Health Study, one of the largest and longest studies to date that has measured abdominal obesity, normal-weight women with a waist of 35 inches or higher had three times the risk of death from heart disease, compared to normal-weight women whose waists were smaller than 35 inches. It’s the belly fat that kills.
If your BMI is high, check it against your waist measurement to be confident that it truly indicates a problem. Anyone can measure their own waist circumference, but waist measurements are often done incorrectly. For accurate waist measurement results, adhere to the guidelines to the left from the protocol of the International Chair on Cardiometabolic Risk.
Waist measurements only need to be checked intermittently – every three to six months or so – to track long-term trends.
Another way to evaluate body weight and health is to compare waist size to height. Waist size should be no more than half your height; so for example, a five-foot-four-inch female should have a waist size no more than 32 inches.
BMI and Age
Does BMI increase with age? In most instances, yes, if you let it. But the science of aging is giving us some very encouraging information – in general, people of almost any age can often add years or even decades of higher quality life through simple lifestyle changes. I mention this because too often I’ve seen people in their seventies, eighties and nineties essentially throw in the towel and rely on drugs alone. What I tell many of my patients is: “You don’t have to settle for steady decline! It can be a fun challenge to making your life better.”
When is it too late to start? Almost never. You should consult with your own doctor first of course, but generally, the correct simple living habits can make a dramatic improvement for anyone of any age. I’ve seen many examples of people who modify their diets and start getting moderate exercise in their eighties and nineties with outstanding results.
What’s often called “normal aging” is not necessarily normal. Most people can make the most out of their life as they age, as long as they take the time to think about what they are doing and make a few changes. This often holds true for people with chronic conditions like diabetes and cardiovascular issues. If you find yourself carrying more weight with age, you are most likely in a perfect place to start making a few small changes that will yield big benefits.
Fixing the Problem
As obesity rates have soared, people’s perceptions of what constitutes a healthy weight appear to have shifted: A U.S. study comparing weight perception surveys from the late 1980s to the early 2000s found that in the early 2000s, people were more likely to consider their own weight “about right” instead of “overweight”. Some of these people were at a healthy weight but others were not. Don’t fool yourself, excess weight is a serious problem but fortunately one that can be remedied in most cases.
And I always advise my patients to stay away from phony dietary supplements that claim to lower body weight. People who buy them are fooling themselves by trying to take a shortcut that won’t work. If you need medications, your doctor is the place to get them.
In my clinical experience, lifestyle factors such as being active and eating well are at least as important as BMI in predicting the stability of metabolic health. I’ve seen many of my patients take an active role in bringing themselves back to good health through relatively small alterations to their fitness, diet and sleep habits. Don’t be intimidated by the idea of making the small lifestyle changes that can add up to big results. These changes are very straightforward when you know how to go about them.
Helping so many of our patients change their lives for the better is what inspired my colleagues and me to develop the Olumia Life program. It is the first complete guide for people who want a dependable pocket companion that tells them what to do, when to do it and why for healthier lifestyle and appropriate body weight.
I hope you or someone you close to you finds it useful.