July 17, 2014—Why are more than a third of American adults obese? “Too much food” may spring to mind. But while overeating is often blamed for bulging bellies, a study published in The American Journal of Medicine suggests a different culprit: lack of exercise.
About the study
Using data collected in the National Health and Nutrition Examination Survey (NHANES) from 1988 to 2010, researchers at Stanford University looked at the increase in obesity and:
- Calories in. The study showed that Americans’ total daily calorie consumption remained steady over the last 20 years. (Researchers did not examine exactly what types of foods people consumed, a potential limitation of the study.)
- Calories out—aka exercise. In 1994, only 1 percent of American men and 19 percent of women reported sedentary lifestyles. By 2010, nearly half of all men and more than half of all women said they were getting no leisure-time exercise.
Although the researchers did not identify an association between caloric intake and obesity, they did find an association—particularly for women—between lack of exercise and increases in:
- Body mass index (BMI). During the same 22-year span that saw Americans exercising less, the average BMI rose across the board—most dramatically in women ages 18 to 39.
- Abdominal obesity. From 1988 to 2010, average waist circumference increased by 0.37 percent each year in women and by 0.27 percent each year in men.
Read more about the Stanford study here.
Obesity increases the risk for a host of health problems, including:
- Heart disease
- Certain cancers (breast, colon, endometrial)
- Type 2 diabetes
- High blood pressure (hypertension)
- High total cholesterol
- Liver and gallbladder disease
- Sleep apnea
Weight that’s concentrated around the stomach and torso can be even more dangerous. In fact, even for someone with a normal weight and a normal BMI, an oversized waistline increases the risk of an early death. If you’re a woman whose waist measures 35 inches around or more, you’re in the health danger zone. If you’re a man, that measurement is 40 inches or more.
The best way to get control is to understand where you stand now and where you should be in the future. That means doing a little measurement and calculation.
To measure your waist, wrap a tape measure around your middle, just above your hipbones. Breathe out and check the measurement. To calculate your BMI, use this handy tool.
What’s a body to do?
If your numbers are too high, exercise may be part of the solution. Americans have long been advised to shoot for at least 30 minutes of physical activity most days of the week—or 150 minutes of moderate-intensity exercise each week. However, because obesity is a multifaceted problem that can involve culture, environment, genes, metabolism and socioeconomic status in addition to behavior, addressing it may call for more than exercise. If your BMI is high or your waist is large and you want to shed some pounds, talk to your doctor about diet and safe exercises.