Time-restricted eating 'no better' than calorie counting for weight loss in obese adults

A time-restricted eating pattern without focusing on lowering calorie intake is no better than a reduced calorie diet for weight loss among obese adults, according to a recent randomised trial.

The timing of food intake appears to impact on the success of weight-loss therapy. In fact, it is already known that an early time-restricting feeding regime plus a reduced calorie intake, leads to weight loss. But does time-restricted eating without the need for calorie counting improve weight loss compared to focusing on restricting calorie intake?

This was the question posed in a recent randomised controlled trial. Writing in the Annals of Internal Medicine, a team of US researchers explored whether time restricted eating was more effective for weight control and cardiometabolic risk reduction compared with calorie restriction.

In the study, participants were equally randomised to one of three groups: eight-hour time-restricted eating (TRE) between noon and 8pm only and without calorie counting, a 25% calorie restricted diet, or a control group where participants were free to eat over a period of 10 or more hours per day.

Enrolled participants had a body mass index of 30-50 and were advised not to change their current physical activity levels. All participants received dietary counselling every week for the first three months, which reduced to fortnightly between months four and six. The primary outcome was the absolute change in body weight between the time restricting eating, calorie restriction and control groups at 12 months.

Time-restricted eating and weight loss

In total, 77 participants with a mean age of 40 years were included and randomised between the three arms.

At 12 months, compared with the control group, those in the TRE group lost significantly more weight (- 4.61 kg, p < 0.01). Similarly, those assigned to the 25% calorie restricted group also lost a significantly greater amount of weight (-5.42 kg, p < 0.01). However, there was no significant difference in weight loss between the TRE and calorie restricted groups (p = 0.68).

The researchers also found no significant differences between the TRE and calorie restricted groups in relation to changes in blood pressure, lipids or insulin sensitivity.