The more fit you are when you start a weight-loss program, the more weight you could lose, a new study says.

"This research could help us improve the design of our weight-loss programs and suggests that adults with very poor fitness may benefit from additional exercise support during a weight-loss program to achieve higher levels of moderate-to-vigorous physical activity and improve long-term weight loss," said lead researcher Dr. Adnin Zaman. She's an instructor/fellow at University of Colorado Anschutz Medical Campus in Aurora.


The study included 60 overweight and obese adults who were part of an 18-month weight-loss program. It combined a calorie-restricted diet, group-based behavior support and six months of supervised exercise. During that time, participants worked up to 300 minutes a week of moderate-intensity workouts.

After the supervised exercise, participants were told to continue working out at the same level on their own.

At the start of the study, 33 percent of participants had very poor fitness and the rest had poor or better fitness. Body mass index was higher in those with very poor fitness compared to the others. BMI is an estimate of body fat based on weight and height.

At six and 12 months, the groups had no difference in weight loss. But after 18 months, those who were least fit at the start had lost about half as much as the others -- an average 9.5 pounds, compared to 18 pounds for the poor-or-better group.

While all increased the amount of moderate-to-vigorous exercise they could do, the least fit were not able to do as much -- an average 24 minutes a day, compared with 42 minutes a day for the others.

The study was published March 31 in a special supplemental section of the Journal of the Endocrine Society.

Zaman said other factors may have played a role in the results. "Future studies are needed to evaluate whether providing additional exercise support or focusing specifically on improving fitness in adults with low levels of fitness would improve weight loss," she said in a journal news release.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases explains how to choose a safe and successful weight-loss program.

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