Obesity is a condition characterized by excessive accumulation of body fat and increased body weight.
Scientific studies have revealed that obesity is associated with negative effects on health and reduced life expectancy. Obesity is most often defined as a body mass index (BMI) above 30.
There are three forms of obesity: peripheral, central or a combination of both. Peripheral obesity is the accumulation of excess fat in the buttocks, hips and thighs, whereas central obesity is an excess accumulation of fat in the abdominal area. This is an especially dangerous place for fat to build up because it is closely located to the vital organs and their blood supply. The fat can then be released into the blood; this process is responsible for most of the negative health consequences associated with obesity, such as:
- Type 2 diabetes
- Glucose intolerance
- High blood pressure
- Endometrial cancer
- Insulin resistance;
- Altered metabolicprofile
- Metabolic syndrome
- Cardiovascular disease
Faced with these risks, it’s no wonder that you want to know how much you should weigh. But this common and important question is actually the wrong question. For health, the issue is not how much you weigh, but how much abdominal fat you have.
Although it has not been proven that a sedentary lifestyle predisposes to the accumulation of belly fat, there is evidence that regular exercise is associated with less central obesity.
A systematic review found that regular physical activity was associated with a marked reduction in central obesity, even in studies not reporting reductions in body weight
Methods have changed over the years. But when scientists recognized that what matters is not body weight but body fat, standards began to change. The body mass index (BMI), remains enshrined as the standard way to diagnose overweight and obesity.
Evaluating abdominal obesity
The most accurate method is to use computed tomography (CT) or magnetic resonance imaging (MRI) to measure the amount of visceral fat. But they’re expensive and require sophisticated equipment.
A far simpler method is to determine the waist-to-hip ratio. With your abdomen relaxed, measure your waist at the navel. Next, measure your hips at their widest point, usually at the bony prominences. Finally, divide your waist size by your hip size:
Waist (in inches) / Hips (in inches) = ratio
How does your ratio translate into health risk? The chance of suffering a heart attack or stroke increases steadily as a man’s ratio rises above 0.95; for women, risk begins to rise above 0.85.
The waist-to-hip ratio is a very useful tool. But many experts are now turning to an even simpler technique: waist circumference. Because it involves one measurement instead of two, it’s more accurate and reproducible than the waist-to-hip ratio.
Central obesity is defined as waist circumference
≥ 40 inches or 102 cm in males and
≥ 35 inches or 89 cm in females
Health risks of central obesity.
- The large INTERHEART study indicated that central obesity was a stronger predictor of heart attack (myocardial infarction) than general obesity assessed by BMI.
- Metabolic syndrome is a deadly combination of abdominal obesity, high blood pressure, insulin resistance and abnormal cholesterol levels.
- The obesity hypoventilation syndrome is a condition in centrally obese people in which poor breathing leads to lower oxygen levels in their blood. Excessive abdominal fat interferes with the breathing mechanism results in shallow breathing.
- Obstructive sleep apneais common among centrally obese people. This condition is an important cause of high blood pressure, tiredness and depression.
- High blood pressure (hypertension) is a well-known risk factor for heart disease and stroke. Hypertension is more common in obese people than normal weight individuals.
The strong association between central obesity and diverse disease conditions suggests that avoiding the accumulation belly fat or losing belly fat if present, may reduce risk and improve health. Any intervention that will induce weight loss is likely to reduce belly fat.