A new study presented by the Radiological Society of North America at their annual meeting suggests that it’s not how much body fat you have, but rather where your body fat is that determines your health risks. At least when it comes to cardiometabolic risk.
Cardiometabolic risk is how likely you are of suffering from heart disease, a stroke or diabetes. This risk can be increased by things such as stress, poverty, old age, poor diet, lack of exercise, and so on. Distribution of fat can now be added to that list.
Over 70% of Americans are considered to be overweight or obese, says the National Centre for Health Statistics. But individuals with the same weight or BMI can have wildly different risk profiles due to the factors mentioned above. It is also worth noting that (cis) women on average have proportionately more fat than muscle compared to (cis) men.
Phrases such as “apple-shaped” and “pear-shaped” are used to describe the body shapes of people based on where their fat is stored. The first refers to fat being stored around the midsection while the second implies it is stored lower down around the waist and thighs. The type of fat that also affects the cardiometabolic risk, known as ectopic fat, is particularly dangerous. It is found in the abdominal area as well as in muscles and around the liver and other organs.
“We hypothesized that there are gender-based differences in body composition and ectopic fat depots and that these could be associated with gender-specific risk profiles for diseases like diabetes, heart disease and stroke” said Miriam A. Bredella, lead author of the study and radiologist at Massachusetts General Hospital. She is also an associate professor of radiology at Harvard Medical School.
After a study involving 200 overweight or obese people, 109 women and 91 men, Dr Bredella concluded that obese women had more subcutaneous fat while obese men had more ectopic fat.
However, the study involved too small a number to make any large-scale assessment of gender-based differences in fat proportions. Nonetheless, it may reveal about how social systems like gender interact with our physiology, in this case fat composition.
Overall, the study implied that men were more at risk than women, but that ectopic fat was not as high a risk in men as it was in women.
“The detrimental fat depots deep in the belly, muscles and liver are more damaging for cardiometabolic health in women compared to men,” Dr. Bredella said.
In an related study, Dr Bredella looked into the link between sarcopenic obesity, which is the loss of skeletal lean muscle mass due to obesity, and cardiometabolic risk. In young adults, obesity and lack of exercise can lead to sarcopenic obesity.
“But there are also hormonal abnormalities, such as low growth hormone secretion in individuals with abdominal obesity. Growth hormone helps to build muscle mass. Nutrition also plays an important role, and too little intake of protein can lead to muscle loss.”
Results showed that having a low ratio of lean muscle mass to BMI was associated with higher risk and was more pronounced in women than in men.