by Beth Shepard, M.S., ACE-CPT, ACSM-RCEP, Wellcoaches Certified Wellness Coach
Most people know that being overweight or obese increases your risk of serious health problems — it's old news. If your body mass index (BMI) is within a normal range, you probably think you're off the hook, even if you don't exercise or eat right.
Think again. More than a decade of clinical research shows that many people are skinny fat, a popular buzzword describing men and women who appear healthy and fit on the outside. Many of these unsuspecting people have healthy BMIs, but are normal-weight obese; they're over-fat and at risk for developing obesity-related illnesses like heart disease, type 2 diabetes, stroke, and more. What about you?
BMI vs. Body Fat Percent
Body mass index is a number used by health professionals to assess whether or not your weight is in a normal range based on your height. But a normal BMI of 18.5–24.9 offers a weight range of about 35-40 pounds — you could be at either end of the range, or somewhere in the middle, and still be considered normal. It doesn't account for body composition — fat or lean percent — and it's not accurate for heavily muscled or pregnant individuals. In essence, it's an imperfect measurement that offers a quick and easy, best-guess approach for assessing weight-related health risk.
In contrast, body fat percent offers an entirely different picture — it's a measurement that reveals whether or not you're carrying too much fat weight, regardless of the number on the scale.
The Big Deal
The concept of skinny fat is getting a lot of attention because we all know people who seem genetically blessed — maintaining a healthy weight without exercising or watching what they eat. But weight isn't the only thing that matters. Studies show that whatever you weigh, poor nutrition and a sedentary lifestyle elevate your health risks. Check out these research highlights related to the skinny fat concept:
- A recent study found 29% of subjects classified as lean and 80% of subjects classified as overweight via the BMI method fell within the obese category when body fat percentage was measured. Compared to subjects with normal body fat percentage, these individuals also had higher levels of cardiometabolic risk factors such as C-reactive protein, a marker of inflammation.
- Another study of BMI-assessed normal-weight subjects found abnormal metabolic profiles associated with obesity, including elevated triglycerides, glucose, and C-reactive protein; low HDL cholesterol, insulin resistance, and high blood pressure. Subjects with higher body fat percentages were most likely to have abnormal metabolic profiles, despite having a normal BMI.
- A 17-year study of over 37,000 apparently healthy 17-year-old males found risk for heart disease increased 12% with every one unit increase in BMI — even within the normal range.
- In a well-known 1999 study, Dr. Steven Blair and colleagues found that active obese individuals have lower rates of disease and death than normal weight individuals who are sedentary.
What To Do About It
If you think you might fall into the skinny fat category, schedule a preventive health care visit. Your health care provider will evaluate your health risks and recommend appropriate tests, treatments or lifestyle changes. Ask about your numbers — such as cholesterol and blood pressure — they're important to know. Depending on your needs, you may be referred to other health professionals, such as an exercise specialist or registered dietitian to help you establish an exercise program and improve your eating habits.
Should I Get My Body Fat Measured?
It's up to you. BMI aside, if your health measures are normal, you're exercising regularly, and eating right, you probably don't need a body fat test — unless you're curious. Cost, comfort, and accuracy varies considerably among different methods.
The most important thing to keep in mind is that one number — whether it's weight, BMI, or body fat % — doesn't offer a complete picture of your health. Your everyday behaviors have an incredible amount of power over whether you develop preventable diseases that could cut your life short — or remain vibrant, healthy, and loving your life well into your later years. Make health-promoting choices each day — and chase the skinny fat away.
- Shea JL, King MT, Yi Y, Gulliver W, Sun G, Body fat percentage is associated with cardiometabolic dysregulation in BMI-defined normal weight subjects, Nutr Metab Cardiovasc Dis. 2011 Jan 5. [Epub ahead of print]
- Gómez-Ambrosi J, Silva C, Galofré JC, Escalada J, Santos S, Millán D, Vila N, Ibañez P, Gil MJ, Valentí V, Rotellar F, Ramírez B, Salvador J, Frühbeck G. Body mass index classification misses subjects with increased cardiometabolic risk factors related to elevated adiposity. Int J Obes (Lond). 2011 May 17. [Epub ahead of print]
- Blair SN, Brodney S. Effects of physical inactivity and obesity on morbidity and mortality: current evidence and research issues. Med Sci Sports Exerc. 1999 Nov;31(11 Suppl):S646-62.
- Antonino De Lorenzo, Vera Del Gobbo, Maria Grazia Premrov, Mario Bigioni, Fabio Galvano and Laura Di Renzo Normal-weight obese syndrome: early inflammation? American Journal of Clinical Nutrition, Vol. 85, No. 1, 40-45, January 2007
- 5. Tirosh A, Shai I, Afek A, et al. Adolescent BMI trajectory and risk of diabetes versus coronary disease. N Engl J Med. 2011;364(14):1315-1325, cited in http://contemporarypediatrics.modernmedicine.com/contpeds/Even-high-normal-BMIs-in-adolescents-increase-midl/ArticleStandard/Article/detail/716688