Time-restricted eating produces similar weight loss results as calorie restriction

Key takeaways:

• Time-restricting eating participants lost approximately 10 more pounds compared with a control group after 1 year.
• Calorie restriction participants lost approximately 12 more pounds vs. the control group.

Both time-restricted eating and calorie restriction were more effective in reducing weight at 1 year among a diverse participant population compared with no intervention, according to results of a small randomized controlled trial.

Researchers further reported that calorie restriction (CR) was associated with greater weight loss than time-restricted eating (TRE); however, the difference was not statistically significant.

TRE has increased in popularity because of its simplicity and lack of calorie counting, but few studies have evaluated the efficacy of TRE for weight loss, Shuhao Lin, MS, RD, LDN, a clinical research coordinator at the University of Illinois Chicago, and colleagues wrote in Annals of Internal Medicine.

They also pointed out that prior trials comparing TRE with other dietary interventions, like daily CR, lacked generalizability among ethnically and racially diverse populations.

According to CDC data, non-Hispanic Black adults had the highest age-adjusted prevalence of obesity from 2017 to March 2020 at 49.9%, followed by Hispanic adults at 45.6%. As a result, “effective nonpharmacologic weight loss regimens are critically needed in these populations,” Lin and colleagues wrote.

Thus, the researchers conducted a 12-month randomized controlled trial in which 90 participants with obesity were assigned to either TRE (n = 30), CR (n = 30) or control (n = 30) groups.

TRE participants were instructed to eat all food between 12:00 p.m. and 8:00 p.m. without calorie counting, whereas CR participants had to reduce their energy intake by 25% every day. Both groups met with a dietician weekly and biweekly up to 6 months, and then monthly between 6 and 12 months.

Meanwhile, control group participants had to maintain their baseline weight and eating window of 10 hours a day through the study.

All three groups had follow-ups at baseline, 3 months and 12 months.

Overall, 77 participants completed the study. The participants had a mean age of 40 years, 82% were women, 33% were Black and 46% were Hispanic individuals.

The researchers found that, compared with the control group, participants in the TRE group consumed 425 fewer calories per day, and those in the CR group consumed 405 fewer calories per day.

In addition, absolute weight loss at 1 year compared with the control group was:

• –4.61 kg (95% CI, –7.37 to –1.85) for the TRE group; and
• –5.42 kg (95% CI, –9.13 to –1.71) for the CR group.

Weight loss as a percentage of baseline body weight was –4.87% (95% CI, –7.61 to –2.13) for the TRE group and –5.3% (95% CI, –9.06% to –1.54%) for the CR group vs. the control group.

Participants in both the TRE and CR groups demonstrated “moderately high adherence and decreased energy intake to a meaningful level,” Lin and colleagues wrote.

The researchers added that the study showed TRE is both an effective and feasible intervention within a diverse population.

“Time-restricted eating is undoubtedly an attractive approach to weight loss in that it does not require the purchase of expensive food products, allows persons to continue consuming familiar foods, and omits complicated calorie tracking,” they wrote. “Given the paucity of literature on nutrition strategies in this cohort, this study of a racially and ethnically diverse population may help to fill in critical knowledge gaps and improve the health of underrepresented racial and ethnic groups.”

In a related editorial, Adam H. Gilden, MD, MSCE, an associate professor of medicine at the Colorado University School of Medicine, and Victoria A. Catenacci, MD, an associate professor of medicine at the same institution, wrote that TRE can be an effective weight loss strategy “if there is concurrent nutritional counseling to support healthy food choices.”

However, because TRE is not more effective than daily CR, “patient preference and other individual-specific considerations regarding ease of implementation can guide clinical choice of dietary weight loss intervention,” Gilden and Vatenacci wrote.

They concluded that further research is needed “to understand who may do better with TRE vs. CR.”

References:

• Adult obesity facts. https://www.cdc.gov/obesity/data/adult.html. Accessed June 28, 2023.
• Gilden A, Catenacci V. Ann Intern Med. 2023;doi:10.7326/M23-1396.
• Lin S, et al. Ann Intern Med. 2023;doi:10.7326/M23-0052.