Early time-restricted eating effective for weight loss in obese adults

Early time-restricted eating (eTRE), a form of intermittent fasting that includes a shortened eating window within 8 hours early in the day, was associated with a greater weight loss among adults with obesity than eating over a window of ≥12 hours, according to a recent study.

“In our trial, the eTRE group lost an additional 2.3 kg relative to the control group, [indicating] an approximately 50 percent improvement in weight loss,” according to the researchers.

This parallel-group trial analysed 90 adults (mean age 43 years, 80 percent female) who were newly diagnosed with obesity (mean BMI 39.6 kg/m²) and received weight-loss treatment with energy restriction (ER) at the Weight Loss Medicine Clinic of the University of Alabama at Birmingham Hospital in Alabama, US. Participants were randomized in a 1:1 ratio to follow either an 8-hour eating window between 7:00 am and 3:00 pm (eTRE group) or a self-selected ≥12-hour eating window (control group) for ≥6 days/week for 14 weeks in addition to ER. They were also instructed to follow a hypocaloric diet (500 kcal/day) and to perform an exercise from 75–150 minutes/week. [JAMA Intern Med 2022;doi:10.1001/jamainternmed.2022.3050]

Although both groups achieved a clinically meaningful weight loss from baseline, patients in the eTRE group achieved greater weight loss than those in the control group at week 14 (mean -6.3 vs -4.0 kg; p<0.001).

However, the differences in absolute fat loss (mean difference, -1.4 kg; p=0.09) and the ratio of fat loss to weight loss (mean difference, -4.2 percent; p=0.43) did not differ significantly between groups.

Mean differences in trunk fat (-0.9 kg), visceral fat (-0.1 kg), waist circumference (-1.5 cm), or appendicular lean mass (-0.1 kg) were also not statistically different between the two groups.

With regard to the effect of eTRE intervention on cardiometabolic outcomes, those on eTRE experienced improved diastolic blood pressure (BP) than those on the control regimen (mean difference, -4.0 mm Hg; p=0.04). All other cardiometabolic risk factors evaluated, as well as food intake, physical activity, and sleep outcomes were comparable between the two groups, noted the researchers.

“Our data suggest that eTRE is feasible, as participants adhered 6.0 days per week on average, and most participants adhered ≥5 days per week,” the researchers noted.

The greater improvements in total mood disturbances, including fatigue-inertia, vigour-activity, and feelings of depression/dejection, in the eTRE vs the control group may have helped with adherence, they added.

“[Overall,] the key finding of this study is that eTRE was more effective for losing weight [and lowering diastolic BP, suggesting that this] intervention may be an effective treatment for both obesity and hypertension, than eating over a period of ≥12 hours,” said the researchers.

The eTRE intervention seemed acceptable to most participants who followed the regimen, as nearly half stated that they plan to continue the regimen even after the study ended, they added.