Fat and Fit
Updated June 09, 2015.
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
For several years now, doctors have used the body mass index (BMI) to decide whether their patients are underweight (BMI less than 20), overweight (25 to 29.9), obese (above 30), extremely obese (BMI 35 or above), or "just right" (BMI 20 to 24.9). You can calculate your own BMI using your height and weight.
Numerous studies attempting to correlate BMI with subsequent health risk seem to agree on two key points.
First, patients who are obese or extremely obese have a greatly increased risk of cardiovascular disease and death. Second, patients who are underweight also have an increased risk of death. (This is thought to be mainly because of underlying disease processes -- such as heart disease, lung disease, cancer or infection -- which themselves often produce weight loss as the disease progresses.)
However, the health risk for people whose BMI places them in the "overweight" category (BMI 25 to 29.9) has been a bit more difficult to assess. Some studies, such as the one below authored by Adams and colleagues, indicate that overweight patients have increased risk. Others, such as the Romero-Corral study (also discussed below), suggest they may not.
So which is it?
More recent studies seem to provide the answer. It turns out that for patients in the "overweight" category, waist-to-hip ratio and overall level of fitness accurately reflect their cardiac risk. For instance, in a recent study, overweight men with reduced fitness levels had nearly twice as much abdominal fat (and thus, increased waist-to-hip ratios) as overweight men who were physically fit (and whose waist-to-hip ratios tended to be lower).
Consequently, they had worse metabolic risk profiles for cardiac disease. Even men in the "obese" category benefited by maintaining a good level of cardiovascular fitness; they had less abdominal fat than patients with similar BMIs who were physically unfit. Being fat and fit, therefore, is much better than just being fat.
Measure your BMI. If you are merely "overweight" (BMI 25 to 29.9), measure your waist-to-hip ratio. If you are physically active and your waist-to-hip ratio is in the normal range, your risk profile is probably not being significantly impacted by your weight. If you are not physically active and your waist-to-hip ratio is abnormal, you are at increased risk.
If you are obese or extremely obese (BMI 30 or above), you have greatly increased cardiac risk and should attempt to lose weight. However, even obese individuals improve their metabolic risk profile if they can remain physically active and physically fit.
No matter what your BMI profile, physical activity can reduce abdominal obesity and therefore cardiac risk.
Sources:
Adams KF, Schatzkin A, Harris TB, et al. Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years old. N Engl J Med 2006; 355:763-778.
Romero-Corral A, Montori VM, Somers VK, et al. Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: A systematic review of cohort studies. Lancet 2006; 368: 666-678.
See R, Abdullah SM, McGuire DK, et al. The association of differing measures of overweight and obesity with prevalent atherosclerosis. J Am Coll Cardiol 2007; 50:752-759.
Arsenault BJ, Lachance D, Lemieux I, et al. Visceral adipose tissue accumulation, cardiorespiratory fitness and features of the metabolic syndrome. Arch Intern Med 2007; 167:1518-1525.
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
For several years now, doctors have used the body mass index (BMI) to decide whether their patients are underweight (BMI less than 20), overweight (25 to 29.9), obese (above 30), extremely obese (BMI 35 or above), or "just right" (BMI 20 to 24.9). You can calculate your own BMI using your height and weight.
Numerous studies attempting to correlate BMI with subsequent health risk seem to agree on two key points.
First, patients who are obese or extremely obese have a greatly increased risk of cardiovascular disease and death. Second, patients who are underweight also have an increased risk of death. (This is thought to be mainly because of underlying disease processes -- such as heart disease, lung disease, cancer or infection -- which themselves often produce weight loss as the disease progresses.)
However, the health risk for people whose BMI places them in the "overweight" category (BMI 25 to 29.9) has been a bit more difficult to assess. Some studies, such as the one below authored by Adams and colleagues, indicate that overweight patients have increased risk. Others, such as the Romero-Corral study (also discussed below), suggest they may not.
So which is it?
More recent studies seem to provide the answer. It turns out that for patients in the "overweight" category, waist-to-hip ratio and overall level of fitness accurately reflect their cardiac risk. For instance, in a recent study, overweight men with reduced fitness levels had nearly twice as much abdominal fat (and thus, increased waist-to-hip ratios) as overweight men who were physically fit (and whose waist-to-hip ratios tended to be lower).
Consequently, they had worse metabolic risk profiles for cardiac disease. Even men in the "obese" category benefited by maintaining a good level of cardiovascular fitness; they had less abdominal fat than patients with similar BMIs who were physically unfit. Being fat and fit, therefore, is much better than just being fat.
The Bottom Line
If your BMI classifies you as overweight, but you are physically fit and your abdominal fat is not excessive, it appears that your weight itself is probably not a major contributor to your cardiac risk profile.Measure your BMI. If you are merely "overweight" (BMI 25 to 29.9), measure your waist-to-hip ratio. If you are physically active and your waist-to-hip ratio is in the normal range, your risk profile is probably not being significantly impacted by your weight. If you are not physically active and your waist-to-hip ratio is abnormal, you are at increased risk.
If you are obese or extremely obese (BMI 30 or above), you have greatly increased cardiac risk and should attempt to lose weight. However, even obese individuals improve their metabolic risk profile if they can remain physically active and physically fit.
No matter what your BMI profile, physical activity can reduce abdominal obesity and therefore cardiac risk.
Sources:
Adams KF, Schatzkin A, Harris TB, et al. Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years old. N Engl J Med 2006; 355:763-778.
Romero-Corral A, Montori VM, Somers VK, et al. Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: A systematic review of cohort studies. Lancet 2006; 368: 666-678.
See R, Abdullah SM, McGuire DK, et al. The association of differing measures of overweight and obesity with prevalent atherosclerosis. J Am Coll Cardiol 2007; 50:752-759.
Arsenault BJ, Lachance D, Lemieux I, et al. Visceral adipose tissue accumulation, cardiorespiratory fitness and features of the metabolic syndrome. Arch Intern Med 2007; 167:1518-1525.
