Complutense University of Madrid-led researchers report that eating earlier in the day blunts the weight gain ordinarily predicted by a high genetic score for obesity, according to the Medical Xpress.

Meal timing has drawn attention for associated effects on metabolism, energy expenditure, and circadian alignment. Zeitgeber, a rhythmically occurring body phenomenon which acts as a cue in the regulation of the body's circadian rhythms, can also synchronize metabolic tissues such as the liver, pancreas, and adipose tissue.

Changes in food timing can alter zeitgeber, leading to a change in the molecular timing of circadian clock cues and, consequently, rhythms in metabolic function.

Peripheral oscillators in metabolic organs and tissues sensitive to food timing may become desynchronized from the central clock, which is highly sensitive to environmental light. It is hypothesized that such internal circadian misalignment may contribute to adverse cardiometabolic traits and obesity.

In the study, "Early meal timing attenuates high polygenic risk of obesity," published in Obesity, the team performed linear regression analyses to test whether meal timing interacts with a genome-wide polygenic score on BMI and long-term weight-loss maintenance.

Participants included 1,195 adults with overweight or obesity (mean age 41 years, 80.8% female) enrolled at six weight-loss clinics across Spain through the Obesity, Nutrigenetics, Timing, and Mediterranean (ONTIME) study, which combined a 16-week behavioral weight-loss treatment with a post-treatment weight assessment at around 12 years (mean 12 ± 3 y).

Investigators calculated a polygenic risk score for BMI from 900,492 single-nucleotide polymorphisms and assessed the timing of meals. Midpoint of meal intake was calculated as the halfway time between a participant's first and last meals, weighted across weekdays and weekends. Linear regression models adjusted for age, sex, clinic site, and principal ancestry components.

Each hour of later midpoint corresponded to a 0.952 kg/m2 higher baseline BMI and a 2.2% rise in body weight at 12 years (± 3 y) after treatment. Within the highest polygenic risk tertile, BMI climbed by about 2.21 kg/m2 for every hour of meal delay. No association appeared in lower-risk groups.

The authors conclude that meal timing is associated with weight-loss maintenance and moderates genetic risk, suggesting that early eating could form part of personalized obesity interventions.