Exercise may not boost weight loss compared with diet alone

Participants adhering to a calorie-restricted diet who exercised approximately 1.5 hours per week for 1 year had about the same amount of weight loss as those on the same diet who exercised nearly 4 hours per week, according to research presented at Nutrition 2020.

The meeting was held virtually after initially being canceled because of concerns about COVID-19.

“These findings confirm that meaningful weight loss can be achieved through behavior-focused modifications,” Carli A. Liguori, MS, RDN, LDN, a visiting instructor at the University of Pittsburgh, told Healio Primary Care. “There is often concern that when exercise is increased, there may be a compensation with a decline in diet quality. This was not the case. All groups maintained significant reductions in calories and fat at the 6- and 12-month time points, regardless of increases in exercise.”

Liguori and colleagues evaluated whether different levels of physical activity affected dietary outcomes in behavioral weight loss interventions among adults who were overweight.

They randomly assigned 383 participants to follow a reduced calorie diet of 1,200 to 1,800 calories per day (n = 127) for 1 year, the reduced calorie diet and a moderate level of physical activity that progressed to 150 mins per week (n = 129), or the reduced calorie diet and a high level of physical activity that progressed to 250 minutes per week (n = 127).

All participants received in-person sessions weekly during the first 6 months of the intervention, and a combination of in-person and phone sessions for months 7 through 12. Using the Dietary History Questionnaire II, the researchers assessed participant’s dietary intake, physical activity level and weight.

Over the year, the researchers found that physical activity increased from 65.4±73.8 minutes per week to 88.2±104.3 minutes per week in the diet alone group, from 68.7±93.8 minutes per week to 179.1±125.3 minutes per week in the moderate physical activity group, and from 71.5±84.4 minutes per week to 228.8±148.3 minutes per week in the high physical activity group.

Liguori and colleagues reported that at 12 months, weight loss was –9.9±8.3 kg in the diet-alone group, –10.8±8.2 kg in the moderate-physical-activity group and –9.5±7.3 kg in the high-physical-activity group. There was no significant difference in weight loss between the groups.

They also found that energy intake decreased in all groups by –495±25.8 kcal per day at month 6 and by –502±25.0 kcal per day at month 12. The percentage of daily fat intake also decreased among participants by –5±0.4% at month 6 and by –3.8±0.4% at month 12.

There was no significant difference in participants’ percentage of carbohydrate and protein intake between the groups, according to the researchers.

Liguori noted there was a high retention rate among participants, which showed that the interventions had a high level of acceptability.

“This is something people are interested in and enjoy enough to continue to keep coming back each week,” Liguori said. “In addition, these findings underline the importance of good nutrition when trying to lose weight. While exercise is absolutely an important piece of the puzzle, we saw that managing the diet was the driving force for weight reduction in our sample.” – by Erin Michael

Reference:

Ligouri CA, et al. Abstract P28-014-20. Presented at: Nutrition 2020; June 1-4, 2020; Virtual.