Timed eating may modestly limit an early metabolic slowdown
After one week, metabolic adaptation averaged minus 13 kilocalories with timed eating versus minus 83 kilocalories without it; resting energy use did not differ.
1 week
Limit: DXA misses water and organ-mass changes, potentially distorting estimates of metabolic slowdown
Edited by Boris Djordjevic · AgingResearch.News
In a randomized trial, 100 adults aged 20–60 with severe obesity were prescribed diets providing 60% of their estimated daily energy expenditure for one week. One group was also told to eat only from 10 a.m. to 6 p.m. Researchers measured resting energy use and calculated metabolic adaptation: the change beyond what they predicted from body composition.
The results suggested that timed eating modestly reduced this early adaptation. However, resting energy use did not differ between groups after accounting for starting levels and body composition. Timed eating did not substantially alter hormone or appetite responses. Fat-free mass, everything in the body other than fat, fell by about 800 grams with timed eating versus about 100 grams with calorie restriction alone.
Why it matters
For adults managing obesity as they age, the unresolved question is whether these modest early metabolic effects translate into meaningful long-term weight-management benefits.
Caveats
This one-week trial did not test lasting weight-management benefits. The findings do not cover people outside ages 20–60 or those taking weight-loss medications, who were excluded.
From the paper
- Participants
A total of 100 adults were randomized between 2022 and 2024, and all were included in the analyses (n = 50 in TRE + ER).
- Who took part
Eligible participants were adults (20–60 years old) with severe obesity (BMI ≥ 40 kg/m²).
- Ages
Their mean age was ~33 years and BMI was ~44 kg/m².
- Duration
The interventions were carried out for 7 d (CER, IQR = 5 d and TRE + ER, IQR = 2 d).
- Limitation
The short intervention period, inherent to the objective of evaluating early AT, was challenging due to subtle changes in body composition and RMR.
- Adaptive thermogenesis
Mean early AT values, calculated according to Nunes et al., were significantly lower in the TRE + ER compared to the CER group (−13 ± 160 kcal vs. −83 ± 150 kcal; p = 0.038).
- Resting metabolic rate
RMR at week 1 did not differ between groups after adjustment for baseline RMR, FFM week1, and FM week1 (β_group = 47 ± 32 kcal/day; p = 0.148).
- Hunger
AUC of hunger increased in the CER group (24 cm*min) and decreased in the TRE + ER (−14 cm*min; group x time interaction, p = 0.048).
Quoted word for word from the full text on PubMed Central.
Time-restricted feeding is part of Bryan Johnson's Blueprint
The paper
Universidade do Estado do Rio de Janeiro
Journal of Human Nutrition and Dietetics, Jun 2026, Open access
