Skinny Fat

15 percent of people with prediabetes are thin. Why they might face the biggest risks of all.

Type 2 diabetes and obesity are so often discussed in the same breath, it’s easy to forget that a normal BMI (18.5 to 24.9) won’t stop you from getting the disease. That’s why it was such a surprise when Tom Hanks recently announced that he has type 2 diabetes; after all, in general (movie roles notwithstanding) Tom is a relatively trim guy. Yet according to the National Institutes of Health, about 15% of type 2 diabetics don’t qualify as overweight. But being thin is still better than being obese, right? In most cases, yes. But when it comes to surviving diabetes, things get a bit more complicated.

A study recently published in the Journal of the American Medical Association pooled data on more than 2,500 diabetes patients who were tracked for an average of 18 years while participating in five major medical studies. Analysis revealed that a greater number of patients who had a normal BMI at the time of diagnosis had died by the end of each study than patients who were overweight or obese when treatment began. Yes, you read that correctly; more thin people died than fat ones.

The authors offered up a few theories that could explain the counter-intuitive results:

The “skinny-fat” factor.

Body Mass Index is based on height and weight; it doesn’t take into account fat-to-muscle ratio. Muscle weighs more than fat, so it drives up BMI, but heavier individuals with good muscle tone have health advantages over lightweight and flabby (a.k.a. “skinny-fat”) people. For one, muscle tissue is less insulin resistant than fatty tissue, and research suggests that insulin resistance is the primary underlying factor in cardiovascular disease. That means the less muscle you have compared to fat, the higher the chances you’ll die of heart failure.

Apples are more at risk than pears.

When the study authors took waist-circumference into account, it was clear that pot-bellied patients with normal BMIs had a higher risk of mortality than those with higher BMIs but flatter stomachs. This is likely due to the fact that fat stored closer to vital organs is more dangerous to your health than fat that lives low down in your hips, butt, or thighs.

Docs may overlook diabetes in thinner patients.

It’s possible that physicians aren’t as quick to suspect that diabetes or its complications are to blame for a non-overweight patient’s symptoms. As a result, slimmer patients may not be tested as often or treated as aggressively.

It could be genetics.

There’s evidence that normal-weight diabetics have a genetic profile that’s different from those who are overweight or obese. Those same genetic variances might make the thinner set more susceptible to other illnesses, increasing their mortality rate.

So what’s a skinny-fat person to do? Mark Hyman, MD, an expert on diabetes and author of The Blood Sugar Solution recommends that all normal weight individuals who have an excess of fat request two special tests that can help predict diabetes and heart disease: A Glucose Tolerance Test that measures blood sugar and insulin levels while fasting as well as one and two hours after a 75-gram glucose drink, and a NMR Lipid Particle Test that measures the size and quantity of cholesterol particles.

As you might guess, Hyman also advises that skinny-fats get in better shape, stat, by improving the quality of their sleep, engaging in cardio and strength training, taking fish oil and vitamin D supplements, and consuming less sugar/simple carbs and more protein and plant-derived foods. Your BMI may inch out of the normal range once you start pumping iron, but your odds of living longer will be on the rise.