How well resistance exercises work may depend on a woman's genetic risk for obesity, new research suggests.
Exercise not a one-size-fits-all
Strength-building workouts seem to be most effective for those with a low genetic risk for a high body-mass index (BMI), the study found. BMI is a rough estimate of a person's body fat – the higher the number, the more fat a person has.
Read: How accurate is the BMI?
"This doesn't mean that resistance training is futile for women with higher genetic risk for obesity. It means those with lower genetic risk just benefited more," said Jennifer Bea, an assistant professor at the University of Arizona College of Medicine in Tucson.
"We have previously shown that the resistance training was important for these women in many other ways, including improved bone density. Like most interventions, exercise is not a one-size-fits-all proposition. People with higher genetic risk scores for higher BMI may benefit more from aerobic training, for example," Bea said in a university news release.
Researchers examined the genetic markers of nearly 150 women. They were between 30 and 65 years old. All participated in the year-long Bone Estrogen and Strength Training (BEST) study. Each woman received a genetic risk score for obesity, which was based on 21 genetic markers, or indicators, believed to affect body weight.
More research needed
Eighty-four women were asked to participate in supervised, high-intensity resistance training and moderate weight-bearing exercises. The exercise sessions lasted for 75 minutes each. The women were asked to do these exercises three days a week for one year.
During this time, the women took calcium supplements but made no other changes to their typical diet. The participants recorded their food intake at random intervals.
Read: Why you should be taking a calcium supplement in your twenties
The researchers found that the benefits of resistance training, which included weight loss as well as loss of body fat and belly fat, depended on a woman's genetics and her risk for obesity.
The study was published recently in the International Journal of Obesity.
More research is needed, the study authors pointed out. They said that future studies should include a more diverse group of people. And they added that future studies should also identify ideal weight-management strategies based on an individual's genetic profile.
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Image: Resistance training from Shutterstock