Active Women in Their 70s Beat Genetic Propensity to Obesity

Marlene Busko

June 13, 2018

In a large genetic study, women in their 70s had a healthy weight despite a genetic predisposition to become obese as long as they were physically active more than 150 minutes a week.

The findings are based on gene analysis and questionnaire replies from more than 8000 women of European ancestry who were 50 to 80 years old and took part in the Women's Health Initiative (WHI).

The study was published online in Menopause.

"Our sample [of middle-aged and older women] is the first to show that in the 70- to 79-year-old age group, exercise can mitigate the genetic effects of obesity,” said lead author Heather Ochs-Balcom, PhD, associate professor of epidemiology and environmental health at the School of Public Health and Health Professions, University at Buffalo, New York, in a statement by the university.

"Our work suggests that in older age we can overcome our destiny for obesity — given to us by our parents — through exercise," she stressed.

Moreover, exercise has other benefits for elderly people, Ochs-Balcom pointed out; it mitigates muscle loss that comes with age, which helps reduce the risk of falls, for example. 

"Our findings point to the importance of promoting and maintaining healthy behaviors particularly in older adults to maximize quality of life," the researchers state.

Effect of Healthy Aging on Genetic Risk of Obesity

Relatively little is known about whether genetic predisposition to obesity can be mitigated in older age by healthy behaviors such as physical activity, Ochs-Balcom and colleagues explain.  

To investigate this, they examined data from 8206 women participants in the WHI, who were a mean age of 67.8 years.

They created a genetic risk score for obesity based on 95 single-nucleotide polymorphisms associated with body mass index (BMI).

Then they examined whether the genetic predisposition for obesity was modified by age or self-reported level of physical activity.   

The postmenopausal women were grouped by three age ranges: 50 to 59 years, 60 to 69 years, and 70 to 80 years.

They were also classified as being sedentary or having a low, moderate, or high activity level, where a moderate activity level was about 150 minutes of physical activity a week.

The association between the genetic risk score and BMI was strongest in sedentary women and weakest in the most active women.

Moreover, the effect of a genetic predisposition to obesity was completely attenuated in the 70- to 80-year-old women who were the most physically active.

The researchers acknowledge that other factors may explain part of the findings. "We recognize that it is difficult to tease apart the effects of age, the dynamics of BMI change in older women, and the exposure to an obesogenic environment across the life span," they write.

Nevertheless, "our findings suggest that genetic predisposition to obesity is not wholly deterministic; rather, physical activity may attenuate the influence of inherited obesity susceptibility alleles and suggest that healthy behaviors are still important later in life," Ochs-Balcom and colleagues write.  

This and other studies may encourage the development of lifestyle recommendations coupled with the use of genetic information, they conclude.

The WHI program is funded by the National Heart, Lung, and Blood Institute, National Institutes of Health, and US Department of Health and Human Services. Funding for WHI GARNET was provided through the Genomics and Randomized Trials Network of the ­­­National Human Genome Research Institute. The researchers have reported no relevant financial relationships.

Menopause. Published online May 14, 2018. Abstract

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