Eating Earlier Shapes Weight Outcomes in Genetic Obesity

New research suggests meal timing may influence how genetic risk for obesity affects weight loss and long-term maintenance.

Adults with a high genetic predisposition to obesity experienced higher body weight, slower weight loss, and poorer long-term results when they ate later in the day, while earlier meal timing appeared to reduce the impact of genetic risk.

Study Details

Obesity is influenced by both genetics and lifestyle. While diet quality and calorie intake are well known drivers, meal timing has emerged as another factor that may shape weight outcomes. This study examined whether eating earlier or later in the day interacts with genetic risk to influence body weight and weight loss success in adults enrolled in a structured weight-loss program.

The research focused on adults with overweight or obesity, exploring how daily eating patterns relate to body mass index, the speed of weight loss, and the ability to maintain weight loss over time.

Methodology

Researchers conducted a cross-sectional and prospective observational study involving 1,195 adults participating in a standardized, multimodal weight-loss intervention. Participants were free to eat at times of their choosing, allowing investigators to observe natural meal timing patterns.

Meal timing was defined by calculating the midpoint between the first and last meal of the day. Genetic susceptibility to obesity was assessed using a polygenic risk score for BMI, with participants grouped into low, medium, and high genetic risk categories. Long-term outcomes were available for a subset of 456 participants.

Key Findings

• Each one-hour delay in the midpoint of daily eating was associated with a higher baseline BMI, slower weekly weight loss, and greater long-term weight regain.

• Higher genetic risk scores were strongly linked to higher BMI overall.

• A significant interaction was observed between genetics and meal timing.

• In participants with the highest genetic susceptibility to obesity, each one-hour delay in meal timing was associated with a more than two-unit increase in BMI.

• No meaningful effect of meal timing was seen in participants with lower genetic risk.

Implications for Practice

For patients, these findings suggest that when you eat may matter, especially if you have a strong family or genetic predisposition to obesity. Shifting meals earlier in the day could support weight loss efforts and improve long-term maintenance without changing what foods are eaten.

For clinicians, the study supports integrating chronobiology into obesity care. Personalized weight management strategies may benefit from considering both genetic risk and daily eating schedules. While causal conclusions cannot be drawn, meal timing represents a low-cost, low-risk behavioral adjustment that could complement existing nutrition and pharmacologic approaches.