Overview

• The ONTIME study tracked 1,195 adults with overweight or obesity in Spain who followed a standardized multimodal weight-loss program, recording meal timing, weight trajectories over years, and a polygenic risk score for BMI.
• Participants who ate their main meals later tended to have higher BMI and struggled more to maintain weight loss over the long term.
• The association was most pronounced in people with high genetic predisposition to higher BMI, where each hour later was linked to an increase of more than 2 kg/m², with little effect seen in those at lower genetic risk.
• Study authors urge considering meal timing in prevention and treatment strategies but call for replication in diverse populations using objective measures before changing clinical guidance.
• Related coverage cites circadian rhythm research and recommends practical steps such as earlier dinners and leaving 2–3 hours before bedtime, noting these are general tips rather than prescriptions from the study.