Author(s): ZHENG, C., ZHANG, H.Q., LIAO, Q.W., CHEN, J.J., SUN, F.H., Institution: THE EDUCATION UNIVERSITY OF HONG KONG, Country: CHINA, Abstract-ID: 1403

INTRODUCTION:
Population aging is a global concern, particularly pronounced in Hong Kong. Approximately 35% of older adults are obese, which increases their risk of developing several chronic diseases. Both time-restricted eating (TRE) and exercise have been shown to be effective in addressing obesity. Considering that older adults experience loss of muscle mass, a combination of aerobic and resistance exercises is recommended to prevent muscle loss while maintaining the benefits of weight loss. However, no study has examined the combined effects. We therefore aimed to compare the effects of TRE and aerobic-resistance exercise, either individually or in combination, on body composition and physical function in older adults with obesity.
METHODS:
This was a 16-week, four-arm randomized controlled trial. A total of 60 participants were randomly assigned to one of four groups: Control, TRE, Aerobic-resistance Exercise, and Combined. The TRE group was instructed to eat ad libitum during an 8-hour eating window, followed by a 16-hour fast. The aerobic-resistance exercise group engaged in 90 minutes of exercise three times per week, comprising 40 minutes of brisk walking and 40 minutes of upper- and lower-body resistance exercises, with 5-minute warm-up and cool-down periods. Body composition was measured by Bioelectrical Impedance Analysis, and several physical function tests were conducted. Linear mixed models with Bonferroni post hoc comparisons were used to examine group effects.
RESULTS:
Fifty-six participants completed the study (80.3% female; age, 65.4 ± 3.8 years; body mass index [BMI], 28.8 ± 2.5 kg/m²). Both the TRE and combined groups had a significantly shorter eating window (< 8 hours) than at baseline. After the 16-week intervention, all three intervention groups showed improvements in body composition, with the combined group demonstrating greater improvements in body weight (Combined vs Exercise vs TRE: -2.8 ± 2.4 vs. -1.0 ± 1.0 vs. -0.7 ± 0.9 kg), BMI (-1.1 ± 1.0 vs. -0.3 ± 0.9 vs. -0.5 ± 0.4 kg/m²), and waist circumference (-9.3 ± 3.9 vs. -3.6 ± 1.9 vs. -1.9 ± 2.8 cm). Only the combined group showed a reduction in body fat percentage (-2.4 ± 2.8%) and an increase in muscle mass percentage (2.3 ± 2.7%) simultaneously compared with the control group. Furthermore, the combined group showed improvements in the handgrip strength test (3.2 ± 6.3 kg) compared to the control, and in the 30-second sit-to-stand test (8.8 ± 5.4 times) compared to the control and TRE groups.
CONCLUSION:
Combined TRE and aerobic-resistance exercise is an effective strategy to help older adults lose body weight while improving muscle mass. This combined intervention also improved their physical function. The findings provide valuable information for the treatment of older adults with obesity.