Does excess body fat in 75 year olds buffer mortality rates and increase life expectancy?

Previous studies have suggested that this is the case, but those studies were incomplete, as they did not take into account a person’s weight change over time or how these changes affect life expectancy, but rather just looked at one baseline measure.

This study looked at 29 years of follow-up in which mortality outcomes were assessed as well, significantly longer than the 19 years or less in previous studies.

Subjects were 6,030 Seventh-day Adventists, a unique population because of their lifestyle habits. They were all non-smokers, drink alcohol sparingly, do not eat as much meat as is in the standard American diet, and work out regularly. None had a major chronic disease, and they only looked at those whose weights were stable in case they had weight loss due to a medical condition, affecting the reason for the cause of death.

Results included a gender difference, such that men had a greater risk of mortality with a BMI of 22.3 (3.7 year shorter life expectancy), while women did not have this risk until they had a BMI of 27.4 (2.1 year shorter life expectancy).

It should be noted that a healthy BMI is between 18.5 and 24.9, whereas 25-29.9 is overweight, and 30+, obese.

The researchers are not concluding that being overweight is protective for older women but that they are less sensitive to increased mortality rates with extra weight than are men.

The authors suggest that a potential reason for the gender difference is that “body fat is the primary source of estrogen in post-menopausal females, and a minimum level of estrogen in those years can be protective against heart disease and hip fractures.”

More research is clearly indicated.  

randi morse, randi.morse@gmail.com, newton, ma