Three months of time-restricted eating (TRE), irrespective of whether it is earlier or later in the day, may be a promising strategy for sustaining long-term weight loss in adults with overweight or obesity, according to preliminary results of a randomized controlled trial being presented at this year’s European Congress on Obesity (ECO) in Malaga, Spain (11–14 May).
“Our study found that restricting the eating window to eight hours at any time of the day for three months can result in significant weight loss for at least a year,” said lead author Dr. Alba Camacho-Cardenosa, from the Instituto de Investigación Biosanitaria de Granada (ibs.GRANADA), Granada, Spain. “These benefits can be attributed to the 16-hour fasting window rather than the time of eating.”
Low-calorie diets are well-known ways to lose weight and improve cardiometabolic health. However, long-term adherence is typically low, even among highly motivated people.
TRE, which limits when, but not what people eat, is an increasingly popular intermittent fasting approach that may have greater long-term adherence and lead to better weight maintenance.
A previous randomized controlled trial by the same research team published in Nature Medicine found that reducing the eating window from 12 hours or more to eight hours per day decreases body weight and improves cardiometabolic health.
However, the long-term effects of eating window timing on maintaining benefits are still unknown.
To address this gap, researchers conducted a 12-month follow-up study of a randomized controlled trial involving 99 adults with overweight or obesity in Granada, Spain. The participants, half of whom were women with an average age of 49 and average BMI of 32 kg/m², were randomly assigned to one of four groups for 12 weeks: habitual eating window of 12 hours or more, early time-restricted eating (TRE) with an eight-hour window starting before 10:00, late TRE with an eight-hour window starting after 13:00, or self-selected TRE allowing participants to choose their own eight-hour window. All groups also received education on the Mediterranean diet.
Measurements of body weight, waist circumference, and hip circumference were taken at the beginning of the trial, after the 12-week intervention, and 12 months post-intervention. Results showed that after the initial 12-week intervention, all TRE groups had significantly greater weight loss compared to the habitual eating group. The early TRE group had the highest weight loss, followed by the self-selected TRE and late TRE groups.
At the 12-month follow-up, the habitual eating group had experienced weight gain while all TRE groups maintained greater weight loss compared to the habitual eating group. Waist and hip circumferences also remained lower in the TRE groups compared to the habitual eating group.
