Staring at your reflection, you might not believe a sumo wrestler has less unhealthy fat. Not all fat is created equal. It’s not just the amount that matters but the location. If you are proud of your slender shape despite avoiding exercise and binging on junk food, doctors have a stern warning. Your risk for conditions associated with obesity like high blood pressure and heart ailments might be elevated. On social media it’s sometimes called “skinny-fat.” The medical community calls it TOFI: Thin Outside/Fat Inside. It’s a hidden condition concealed behind a healthy BMI and seemingly ideal frame.
The Problem With BMI
The Body Mass Index was created way back in the 1800s by a Belgian mathematician named Lambert Adolphe Jacques Quetelet. Remembering his name was harder than calculating the BMI. As the U.S. Centers for Disease Control and Prevention explains, if you are using the metric system the formula is weight in kilograms divided by height in meters squared (If your height is in centimeters, further divide by 100). For those using pounds, divide your weight by height in inches squared, then multiply by a conversion factor of 703. If you’re challenged by maths, fear not –– a handy calculator is just a click away. Unfortunately little else has changed about the BMI in nearly 200 years.
The problem should seem obvious. A competitive bodybuilder can have as little as three percent body fat. Yet if he is 6’0 and 225 pounds, his BMI is 30.5 which marks him as obese. A 180 pound couch potato of the same height earns a 24.4 –– which is still in the healthy range. And those sumo wrestlers? Well despite BMIs well over 50, one study determined they have far more fat-free mass (FFM) in and around their organs than untrained college students. They might carry quite a bit of fat around but they don’t have the hidden, dangerous fat that can lead to health issues. TOFIs often have white fat cells wrapped around their kidneys and heart. Their fat infiltrates their livers and is striped throughout their neglected muscles. Besides insulin resistance and diabetes, skinny-fat people are at risk for the same heart conditions as people who are obese. That’s because the dimpled subcutaneous fat just underneath the skin may be what most of us focus on but it isn’t as dangerous. As you get older, this visceral fat may also put you at risk for cognitive decline.
Today there are a host of modern techniques that gauge not only our body fat percentage but even more importantly it’s distribution. The results can be surprising. Magnetic resonance imaging (MRI) enabled examinations of FFM in the wrestlers. Using 2,000 middle-aged British twins, one study examined how the substances involved in metabolism called metabolites have an over 80% accuracy for predicting a subject’s risk for obesity along with other conditions including diabetes and heart problems. The information was gleaned from a blood sample. The challenge is when we diet, fat is reduced from from the feet up and the head down. Even after strict diets, many of us are left with a single unsightly bulge around the abdomen. That’s because your body will work harder to preserve those fat cells nearer your organs than the ones in your legs or arms. Fat cells seem almost to have a mind of their own. Because fat releases hormones and chemicals that affect out moods and even our cognition, scientists view fat almost as an organ like our liver or kidneys. If you have dieted off and on for most of your life, you might have inadvertently “trained” your fat cells to linger around your stomach. Most health problems generally connected to obesity are more specifically linked to belly fat.
If you think you’re at risk for being TOFI, the tale of the tape can help. Stretch a measure along the largest part of your belly –– usually around the navel. The number should be half your height. So if you are 182 centimeters tall (or 72 inches) then your waist should be just over 90 centimeters (or 36 inches). It’s not as accurate as an MRI or a blood test of course, but it’s a good start. No matter what your number, if you are concerned check your habits. Lack of strength training can contribute to the condition, which is why some runners are skinny-fat. So add some weights or even push-ups to your program. What are you eating? Your diet should include plenty of lean protein, whether from animal sources like eggs, chicken and tuna or non-animal like beans and broccoli. Finally, while genetics may determine your body’s shape your choices can change where your fat finds a home.
John Bankston is a published author of over 150 nonfiction books for children and young adults including biographies of Jonas Salk, Gerhard Domak, and Frederick Banting.