Are you thin but fat?
Are you thin in appearance, but fat on the inside?! Wow… this just goes to show you, you can’t judge a book by it’s cover… Just because you are thin, doesn’t mean you are fit and healthy.
A recent study done by researchers at the Mayo Clinic and reported in the European Heart Journal brings to light something I have tried to convince people of for years! Just because someone is not overweight, doesn’t mean they are fit and/or healthy!
They call it Normal Weight Obesity (NWO) and define it as the combination of a normal Body Mass Index (BMI) and high body fat percentage. In their study, researchers found that it is associated with a high prevalence of cardiometabolic dysregulation, metabolic syndrome, and cardiovascular (CV) disease risk factors. In women, NWO is independently associated with increased risk for CV-related mortality.
Based on results of this almost nine-year study, as well as U.S. Census and obesity data, Dr. Lopez-Jimenez and his colleagues estimate that as many as 30 million Americans may fall into the normal-weight-obesity category, many of them unaware they may be at increased heart risk.
The researchers analyzed 6171 subjects from the Third National Health and Nutrition Examination Survey (NHANES III) and the NHANES III mortality study, whose BMI (see BMI Explained below) was within the normal range (18.5–24.9 kg/m2), and who underwent a complete evaluation that included body composition assessment (which gives body fat percentage), blood measurements, and assessment of CV risk factors. They followed the subjects for 8.8 years.
They then divided the subjects into sex-specific tertiles of body fat percentages (BF%). The highest tertile of BF (>23.1% in men and >33.3% in women) was labelled as NWO. When compared with the lowest BF group, the prevalence of metabolic syndrome in subjects with NWO was four-fold higher (16.6 vs. 4.8%, P < 0.0001).
Subjects with NWO also had higher prevalence of high blood lipids (high cholesterol), high blood pressure (men), and CV disease (women). After adjustment, women with NWO showed a significant 2.2-fold increased risk for CV death (HR = 2.2; 95% CI, 1.03–4.67) in comparison to the low BF group.
The Today show featured two women of similar age on this morning’s show to demonstrate the problem. The first woman was 5′6”, 143 lbs (BMI= 23.1)– the second was 5′7”, 140 lbs (BMI = 21.9). Both are “normal” weight according to their height and weight correlations. When you look at them, they both look “fit”. The first of these women was 19% body fat, the second was 27% body fat.
According to this study, the second woman is open to “obesity-related” diseases, like heart disease, type-2 diabetes and metabolic syndrome. What was the difference? The first woman exercises regularly (including strength-training) and eats a healthy diet. The second woman has relied all of her life on her “lucky” genetics. She has never had to worry about her weight, so she didn’t diet or exercise much. It was a shock to her that her health may be compromised.
Doctor’s offices are not testing for body fat percentage. They take your height and weight only. For most of us, conversations about body fat and body composition are more likely to happen during a workout with a personal trainer than at a doctor’s office during an examination. The test isn’t a widely accepted clinical measurement.
It’s crazy! Some claim there isn’t a consensus among medical experts about what percentage of body fat is “normal” or what level indicates higher risk, but the American College of Sports Medicine and the American Council on Exercise consider body fat percentages between 25% and 31% for women, and 18% to 26% for men, as “acceptable.” Women with body fat of 21% to 24%, and men with 14% to 17%, are “fit.”
Some very fit athletes have lower BF, but if you are not exercising well, lower BF is not always healthy. These data are based on many studies (although mostly white, educated people). I will discuss methods and their pros and cons in my next article.
World Health Organization and National Institutes of Health recommendations are that healthy body fat percentages are between 8-25% for men and 21-35% for women, depending on your age. In other words, above 25% for men or 35% for women puts you at a high risk for metabolic diseases such as diabetes, heart disease and high blood pressure. Ideally, you should be in the low to middle of those ranges.
This study suggests that reducing heart risk requires increasing the percentage of lean muscle mass at the expense of body fat. That underscores the importance of exercise in maintaining cardiovascular health—including weight lifting and other resistance training, which helps build lean body mass. Something I have been telling you all along… sigh.
Of course, eating a healthy diet is important in reducing body fat, but if you only restrict calories, you risk losing an equal amount of body fat and muscle tissue and thus you could end up weighing less without significantly reducing your percentage of body fat. So it is more about fat loss than weight loss. And in order to do this, you need to build and/or maintain your muscle mass while losing fat.
Bottom-line: Weight is not where it’s at. As I have been saying all along, just eat the best that you can eat and exercise the best that you can exercise, and practice healthy lifestyle habits. The weight will take care of itself based on your genetics. Thin is not all it’s cracked up to be!
So, with this in mind, do you think you may be “skinny fat”?
BMI – Body Mass Index is a measure of body fat based on height and weight that applies to both adult men and women. It is calculated with the following formula:
But you can go to the National Institutes of Health easy calculator site and put in your height and weight in Imperial units and get an instant calculation.
BF% – Body Fat Percentage is a measure of what percentage of your total body weight is fat. There are many ways to have this measured, some more reliable than others.