Strength training is more important for weight control than you might think – and training only one to two hours a few times a week can make a difference. According to a new study published by PLOS Medicine, researchers at Iowa State University found that people who regularly worked out with resistance exercises were about 20 to 30 percent less likely to become obese over time than people who didn’t. The findings came as researchers tried to evaluate the effectiveness of strength training alone – independent of aerobic exercises – in preventing obesity.
In the study, participants who reported doing little, if any, aerobic exercise and did resistance training almost exclusively were much less likely to become obese than sedentary people. Those who combined working out aerobically and resistance exercises were much less likely to become obese. Many studies have shown that those who get regular aerobic exercise put on less weight with age and are at lower risk of obesity, but far fewer studies have focused on whether strength training influences weight gain.
Study Goes Beyond Measuring BMI
Researchers in the study sought to examine the relationship, if any, between weights and waistlines. The study was unique in that it didn’t rely on BMI (body mass index) as the sole measurement of obesity. The authors said BMI alone isn’t the best indicator of obesity — they measured participants’ actual waist size and body fat percentage. BMI is an indirect measure of body fat that doesn’t consider important details about age, sex, bone structure, or fat distribution, one study in the International Journal of Obesity explains. It’s just two numbers: weight divided by height squared.
By measuring waist circumference or body fat percentage, Iowa State researchers found about 30 percent of men and women in the study who did strength training were less likely to develop obesity over the years. The percentage fell to about 20 percent when researchers used BMI measurements. BMI definitions did not result in finding a reduced risk of obesity for exercisers who did a lot of strength training – about three hours a week or five days a week. “These same high amounts were significantly associated with a reduced risk of obesity defined by [waist circumference] or [body fat percentage],” according to the study.
The results suggest that you can get a lot of benefit from even a little strength training, according to Angelique Brellenthin, a professor of kinesiology at Iowa State who led the new study.
Nearly 12,000 Participated
The study looked at data provided by nearly 12,000 people who had participated in the Aerobics Center Longitudinal Study from 1987 to 2005. They ranged between 18 and 89 in age. The ACLS tracked their lifestyle and exercise habits, weight, and medical history. “Participants were asked if they were currently involved in a muscle-strengthening program, and, if so, they reported their average frequency (days/week) and duration (minutes) of [weight training] at baseline,” according to the researchers.
The Bottom Line
It’s important to incorporate strength-training exercises into your weekly workout routine. For some ideas, see our guides to the Best Arm-Strengthening Workouts and Strength Building Yoga Poses for Newbies.