“If you can get people to exercise at a certain level, you can produce 5 to 7 percent weight loss in almost anybody, and that is clinically significant,” said Donnelly.
In one of his studies, young adults did five aerobic workouts per week for 10 months.
They were divided into two groups: burning either 400 kilocalories or 600 kilocalories per workout. There was also a control group of people not assigned to exercise.
By the end of the study, people in the 400 kilocalories group lost an average of 4.3 percent of their weight, and those in the 600 kilocalories group lost an average of 5.7 percent.
Women and men lost about the same amount of weight. However, some people lost more weight and some less.
To put this in perspective, in order to burn 400 kilocalories, a 160-pound person would need to do one hour of water aerobics. To burn 600 kilocalories, they’d have to run at 5 miles per hour for an hour.
The average daily intake is 1,600 to 2,400 kilocalories for adult women and 2,000 to 3,000 calories for adult men.
It’s not surprising that people in Donnelly’s study lost weight — they were burning an extra 2,000 to 3,000 kilocalories per week.
This amount of exercise essentially burns off an entire day’s worth of food each week.