Call it a muffin top, beer belly or middle-aged spread -- the fact is that by the time most Americans reach adulthood, they have added inches to their waistline. And those extra inches put you at a higher risk for coronary artery disease, type 2 diabetes, stroke, high blood pressure and certain types of cancer. Even if your weight, measured as Body Mass Index (BMI) is normal (18.6 to 24.9), you could still be at a higher risk for disease if your waist circumference is too high. Yet your lifestyle choices, including diet and exercise, can help you fight belly fat.
Why is belly fat so dangerous? There are two different types of fat: subcutaneous fat and visceral abdominal fat, which behave differently metabolically. Subcutaneous fat is distributed throughout the body, including the abdominal area, and as the name suggests, it's the fat that lies underneath the skin. It's what wiggles and jiggles when you walk or what you wrestle with as you squeeze into your jeans. And while having too much isn't benign, the role it has on adverse health risk factors pales in comparison to the other kind of fat. Visceral fat, also called abdominal fat, is fat that is deposited inside the abdominal cavity around organs.
High levels of visceral fat are linked to adverse health indicators: high blood triglycerides, low "good" HDL cholesterol, high "bad" LDL cholesterol, increased markers of inflammation, insulin resistance and nonalcoholic fatty liver disease. A meta-analysis published in the May 2011 issue of the Journal of the American College of Cardiology looked at data from more than 15,900 people with coronary artery disease and concluded that those with abdominal obesity -- even with a normal BMI -- had double the risk of death. A high waist circumference, especially in women, is also a risk factor for developing type 2 diabetes, according to a recent study of biometric markers in more than 300,000 Europeans, published online in MedlinePlus in June 2012.
Beyond body weight
Unfortunately, the measurements typically taken in the doctor's office -- weight and height, which are used to calculate BMI -- are not sensitive enough to determine abdominal fat. People often considered to be at a healthy weight may still have an elevated risk due to abdominal adiposity. A study published in the May 2012 issue of the International Journal of Obesity compared BMI classifications to body fat percentage. Results showed that 29 percent of people classified as normal weight and 80 percent of people classified as overweight had body fat measures putting them within the obesity range (defined as over 25 percent body fat for men and 35 percent for women). Another study published in the January 2012 issue of the same journal, which looked at BMI versus waist circumference as a predictor of health outcomes in 8,064 Canadian adults, concluded that the risk of death from all-causes and specifically cardiovascular disease and cancer was consistently higher among those who had large waist circumferences compared to those with a higher BMI. BMI does not distinguish between individual variations in body composition and variations due to ethnicity, sex and age. Considering your waist circumference is a much more accurate method of determining your risk for disease.
Fighting abdominal fat
Increased age, sex (men more than women), menopause, smoking, a high-caloric diet, sedentary behavior and ethnicity (Asians are at increased risk and African Americans are at lower risk) are risk factors associated with increased abdominal fat. However, making and sticking to lifestyle choices that include diet and exercise can lower levels of abdominal fat. Several diet (see Trim Belly Fat with Food Choices) and lifestyle strategies have been linked with reducing abdominal fat.
Aerobic exercise cuts abdominal fat. As little as 150 minutes per week of moderate intensity aerobic activity, such as brisk walking, dancing and stationary cycling, appears to be enough for reducing abdominal fat, concludes a systematic review and meta-analysis of the effects of exercise on abdominal fat published in Obesity Reviews 2012. While a significant relationship between weight loss and abdominal fat reduction was observed, the benefits of aerobic exercise were seen even without weight loss and, surprisingly, were not dependent upon exercise intensity. Resistance training did not appear to reduce visceral fat. However, it may be effective in preventing abdominal fat in the first place or its re-accumulation when weight is regained after weight loss.
Weight loss is key