Deep down, you may suspect your diet could be cleaner. It'd be a good idea to sub carrots for potato chips for your afternoon snack every now and then, you think. And you should probably hit the gym once in a while. But you still fit into your usual-size pants and button them with no problem. So everything is probably A-OK health-wise, right?
Well, maybe not. You might qualify as "skinny fat" (medically known as metabolically obese normal weight), which, as you've probably guessed, isn't a great thing. But what exactly does it mean to be skinny fat, and is it really that dangerous?
What Is Skinny Fat, Anyway?
Basically, it means that looks can be deceiving. Even if you don't look like you're overweight, you may face the same health issues as someone who qualifies as obese. It all depends on the quantity and quality of your fat tissue, says Eduardo L. Grunvald, MD, a board-certified internal medicine doctor with UC San Diego Health System and director of the UC San Diego Weight Management Program.
"Not all fat is created equal, and not all people are created equal in the sense of body composition," he says. Indeed, some people who look obese may have completely normal blood sugars, cholesterol levels and blood pressure, he says, while others might register as healthy based on body mass index (BMI) but may have body fat-related conditions like diabetes, elevated cholesterol levels, high blood pressure and metabolic syndrome.
Rather than fat being distributed all around the body, for people who are skinny fat, it usually ends up being stored in the belly region, inside and around the organs. "The belly fat is the more dangerous fat," Dr. Grunvald says. It's different than subcutaneous fat, which is just under the skin and most visible to people, says Adam Feit, a certified strength and conditioning specialist and coordinator of performance nutrition at Precision Nutrition.
What the Science Says
Research agrees: Belly fat is dangerous, regardless of how thin or toned your arms and legs are. It's called ectopic fat deposition and has been linked to insulin resistance (which can lead to diabetes and heart disease), metabolic issues and an increased risk of cardiometabolic disease, according to a study published September 2018 in Frontiers in Nutrition.
It may negatively impact the brain, too. In older adults, those with skinny fat body types have been shown to have weakened cognitive performance, according to a June 2018 study published in Clinical Interventions in Aging.
Finally, and most dire of all, being skinny fat could shorten your life. A study published December 2015 in the Annals of Internal Medicine involving more than 15,000 people found men with normal-weight central obesity had two times the mortality rate of those with BMIs that qualified as overweight or obese. Women with normal-weight central obesity had a higher mortality risk as well, though not as marked.
"Traditional BMI charts, which simply take your height and weight into account, do not reflect your amount of lean body mass, which can negatively skew results."
Am I Skinny Fat?
The biggest physical indicator is if your fat is mainly stored in your mid-section and you have a dangerous waist-to-hip ratio. According to Harvard Medical School, here's how to find that ratio:
- Using a flexible cloth measuring tape, measure your bare waist (in inches) at your belly button while relaxed.
- Measure your hips at their widest point (also in inches).
- Divide the waist measurement by the hip measurement to calculate your ratio.
Men with a ratio above 0.95 and women above 0.85 are at increased risk of heart attack and stroke.
Sometimes, though, it's not easy to know whether you qualify as skinny fat based off of this ratio alone. Dr. Grunvald says it's important to also have blood work done and to speak with a doctor about your lifestyle and your family's health history, especially if heart disease and diabetes are common among your relatives.
Feit also suggests having your body fat percentage measured. This is more telling than BMI. "Traditional BMI charts, which simply take your height and weight into account, do not reflect your amount of lean body mass, which can negatively skew results," Feit says.
Read more: How to Estimate Your Body Fat Percentage
How to Go From Skinny Fat to Fit
Dr. Grunvald suggests you get moving. Exercise will improve the way your body responds to insulin, even if you don't see the numbers budge on the scale, he says. But don't rely on cardio only — Feit stresses the importance of a full-body strength training routine to help build muscle.
The Physical Activity Guidelines for Americans — developed by the U.S. Department of Health and Human Services — recommend adults get at least 150 minutes a week or moderate-intensity exercise, or 75 minutes of vigorous activity (or a combination). The guidelines also suggest doing strength-training exercises on two or more days per week.
Take a hard look at your diet, too. According to the September 2018 study published in Frontiers in Nutrition, nutrition is a key-determining factor for insulin resistance and ectopic fat deposition. Dr. Grunvald says processed foods filled with refined sugars and carbohydrates elevate insulin levels, which can increase fat deposits and insulin resistance. "A healthy diet is very important, which is focusing on plant-based foods with lean protein," he says.
Indeed, a study published June 2016 in the Journal of Physical Activity & Health confirmed that a combination of exercise and healthy diet can reduce the amount of dangerous fat sitting in your belly.
So, How Bad Is It Really to Be Skinny Fat?
Unfortunately, it's pretty bad. Being skinny fat presents several serious health concerns — even if it doesn't look that way from the outside. You might look slim and feel good about easily sliding into your skinny jeans, but if you're battling obesity-related health issues, then it's time to make some lifestyle changes.
- Frontiers in Nutrition: "Ectopic Fat Accumulation in Distinct Insulin Resistant Phenotypes; Targets for Personalized Nutritional Interventions"
- Clinical Interventions in Aging: "Sarcopenic Obesity and Cognitive Performance"
- Annals of Internal Medicine: "Normal-Weight Central Obesity: Implications for Total and Cardiovascular Mortality"
- Harvard Medical School: "Abdominal Obesity and Your Health"
- Journal of Physical Activity & Health: "The Effect of Lifestyle Interventions on Excess Ectopic Fat Deposition Measured by Noninvasive Techniques in Overweight and Obese Adults: A Systematic Review and Meta-Analysis"
- Physical Activity Guidelines for Americans, 2nd Edition