According to a new study published this September in the journal BMJ, the bigger our waistlines grow, the higher the risk of death from all causes. But it’s belly fat in particular that is associated with an average of increase in mortality of 11%. This is regardless of your overall body fat content or BMI (body mass index).
Yet the same study showed that bigger hips and thighs were actually associated with a lower mortality rate. This is because the fat around the hips is different than what’s around the belly, and the thighs have a higher muscle content.
These findings are a result of an analysis of 72 studies involving more than 2.5 million participants who were studied from 3 to 24 years. All of the studies explored various measures of weight around the middle of the body, long thought to be a significant risk factor for metabolic resistance, which is a precursor to diabetes, heart disease and more.
All the studies included reported at least three measures of central fatness, like waist circumference, waist-to-hip ratio, and a body-shape metric. Many also included other body size metrics like hip and thigh circumference. For each four-inch increase in waist circumference, there was an 11% higher risk of all-cause mortality. Larger hip and thigh circumferences, however, seemed to have a protective effect. For instance, each four-inch increase in hip circumference was associated with a 10% lower risk of all cause mortality, while each two-inch increase in thigh circumference (more likely muscle) was associated with an 18% lower risk.
Not all fat is created equal
Most measurements of weight focus on the body mass index or BMI which takes your weight in kilograms and divides it by the square of your height in meters. If your BMI is less than 18.5, you’re considered underweight. Your weight is considered normal if your BMI falls between 18.5 and 24.9. You are deemed overweight when your BMI is between 25 and 29.9 and over 30 BMI indicates you are obese.
The problem is this doesn’t take into account lean body mass versus fat mass, or where that fat or muscle resides. Studies have shown that a higher fat content around the middle is more associated with chronic disease such as metabolic syndrome.
Belly fat is unique in that it’s visceral fat, meaning it builds up around organs like the liver, pancreas, intestines, and other internal organs. This fat is called ‘active fat’ because it affects hormone function by secreting a protein that leads to an increased resistance to insulin, which sets us up for type 2 diabetes, high blood pressure, excess cholesterol, heart disease, some cancers and Alzheimer’s disease.
It’s not the same as the weight around our legs, arms or even those love handles on our hips, which is subcutaneous fat and doesn’t affect hormones. Researchers believe belly fat comes not from overeating and sedentary lifestyles, but stress as well. Cortisol, the stress hormone, may play a role. It increases insulin resistance, which adds to fat deposits. Many factors influence how much belly fat you have, like genetics, hormones, diet, stressors, and age. Men in particular tend to accumulate abdominal fat.
Do you have excess belly fat?
Check and see if you’re at risk. Using a tape measure, measure your belly, just above your hips. Women are at risk if the measurement is greater than 35 or more inches (89 centimeters) around the stomach, for men it’s 40 inches (102 centimeters).
While it is difficult to target where we lose fat, losing weight through diet and exercise will reduce all areas of fat, including waist and belly fat. Next week I’ll talk about ways to accomplish this goal.