Time and calorie restricted diet did not offer significant advantage compared to calorie restricted diet alone, according to a recent study from Southern Medical University in Guangzhou, China.¹ The findings were published on Thursday this week in the New England Journal of Medicine.

In this trial, researchers from China recruited overweight and obese adults, mean age 32 years, and randomized them to two intervention groups: time-restricted diet or standard diet. The follow up period was one year. The time-restricted group was instructed to eat only between 8 am and 4 pm, while the other group had no such time restriction. The permissible daily calories for both groups for one year were 1500-1800 calories for men and 1200-1500 calories for women. The baseline mean weight was 88 kg, and mean body mass index (BMI) was 32 kg/m2.

Out of the 139 participants recruited, 118 (~85%) completed the follow up visit at 12 months.

Participants in both groups experienced significant weight loss, from that at baseline, during the study period, 8.0 kg in the time-restricted group vs 6.3 kg in the daily-calorie-restricted group. However, the weight loss in the time-restricted eating group was not significantly greater than the calorie-restricted group (−1.8 kg difference). In addition, no substantial between-group differences were noted for waist circumference, BMI, body fat, lean mass, blood pressure, serum lipids or insulin resistance.

Based on these findings, the study concluded that time and calorie-restricted diet did not offer any extra advantage for weight reduction when compared to daily calorie restriction alone, even though both groups recorded significant weight loss. Likewise, no additional beneficial effects of time restriction were observed for body weight, body fat, or metabolic risk factors.

Instead of eating during a defined time period in the day or fasting on certain days to achieve weight loss, what helps more is reducing calories consumed per day ably supported by physical activity. An intermittent dietary pattern defines when you eat rather than what you eat.

Given the observed weight loss in the time-restricted group, the authors opine that "From a public health point of view, time-restricted eating may turn out to be an approach to accomplish calorie restriction and improve metabolic health without the resource-intensive approach of intentional calorie restriction."

A personalized and sustainable dietary plan that suits the individual lifestyle works best.

Reference

1. Liu D et al. Calorie restriction with or without time-restricted eating in weight loss. N Engl J Med 2022 Apr 21; 386:1495-1504. https://doi.org/10.1056/NEJMoa2114833.