Does Body Fat Protect Women Against Heart Disease?

A new study, conducted by researchers at the University of California, Los Angeles, suggests that women should focus on maintaining or increasing muscle mass instead of losing fat.

To do this, the researchers analyzed body composition data from the National Health and Nutrition Examination Survey (NHANES) Trusted Source 1999-2004 and CVD mortality data from NHANES 1999-2014. In this sense, the data comes from a total of 5,627 women and 5,836 men, all older than 20 years.

Based on the data, the researchers divided the study participants into four groups:

• Low muscle mass and low body fat.
• Low muscle mass and high body fat.
• High muscle mass and low body fat.
• High muscle mass and high body fat.

In both sexes, the raw data showed that higher levels of fat were associated with higher mortality from cerebrovascular disease (CVD), regardless of muscle mass.

However, after accounting for other factors known to affect CVD mortality, the relationship between body fat and risk of dying from CVD completely changed in women.

After making these adjustments, the researchers found that women with high body fat and high muscle mass had a 42% lower risk of dying from CVD compared to women with low muscle mass and low body fat.

In contrast, men with high muscle mass and high body fat had a 26% lower risk of dying from CVD compared to men with low measurements, while those with high muscle mass and low body fat had a 60% lower.

A need for a change in the approach of the advice from health professionals

In this sense, the researchers believe that their study supports the need for a change in the approach of the advice that health professionals provide to women. This shift is toward increasing muscle mass through physical exercise and away from weight loss.

However, it must be emphasized that the apparent protective effect of fat in women only emerged after adjusting for other CVD risk factors. These risk factors include cholesterol levels, high blood pressure, diabetes and prediabetes, and hormone replacement therapy.

There is a very complex interaction between body fat and these other risk factors. For example, excess body weight increases the risk of diabetes and hypertension, which, in turn, increases the risk of CVD.

However, the authors point to several plausible ways in which fat might provide some protection for women. For example, they highlight research suggesting that fat in the thighs and buttocks has a protective effect on metabolism that offsets the damage from abdominal fat.

They also note that in premenopausal women, the body stores approximately 50% of its fat just under the skin in the thighs and buttocks, while in men, the body stores 98% of the fat total deeper into the upper body. However, during and after menopause in women, fatty tissue begins to accumulate in the abdomen, where it is associated with an increased risk of CVD.

The study authors also point out that, in individuals of the same age and weight, the female body tends to accumulate fat by multiplying the number of fat cells, while the male body normally produces larger fat cells. Large (“hypertrophied”) fat cells are associated with negative metabolic consequences.

The researchers also acknowledge some limitations of the study. First, the study design did not allow them to test cause-and-effect relationships between muscle mass or fat mass and CVD mortality, only associations.

In addition, they indicated that the technique they used to measure the volunteers’ body composition, called “dual energy X-ray absorptiometry” or DXA, can overstimulate muscle mass in older people and people who lead a sedentary life.