Uncovering the Role of the Timing of Time-Restricted Eating for Cardiometabolic Health

Obesity is a growing global health challenge, closely linked to an increased risk of chronic diseases like diabetes, cardiovascular disease, and cancer. As calorie restriction can be difficult to maintain in the long-term, new nutritional strategies are emerging. One promising strategy is time-restricted eating (TRE), where individuals consume the desired type and quantity of food within a limited daily eating window (typically 4–10 hours) and fast for the remaining hours. TRE has shown modest reductions in body weight and slight improvements in cardiometabolic health without calorie counting.
Despite these promising results, important questions about the effects of TRE remain unanswered. Abdominal fat comprises two main types: visceral adipose tissue (VAT), located around internal organs and linked to higher cardiometabolic risk, and subcutaneous adipose tissue (SAT), found just under the skin. The effects of TRE on VAT and SAT are still unclear. Furthermore, not only what we eat but also when we eat matters, as our circadian system orchestrates many metabolic processes throughout a 24-hour period. Thus, different TRE schedules—such as early, late, or self-selected eating windows—may have distinct effects on cardiometabolic health.
Study Design: Unraveling the Impact of TRE Timing on Cardiometabolic Health
In our recent study, published in Nature Medicine (https://doi.org/10.1038/s41591-024-03375-y), we investigated the effects of three distinct TRE schedules—an 8-hour eating window in the early part of the day, (early TRE), an 8-hour window later in the day (late TRE), and a participant-selected eating window (self-selected TRE)—combined with usual care (UC), consisting on 2-monthly sessions of a group nutritional education program based on the Mediterranean diet, versus UC alone, over 12 weeks, focusing on VAT changes and cardiometabolic health among men and women with overweight or obesity.
In our multicenter randomized controlled trial conducted in Granada (southern Spain) and Pamplona (northern Spain), a total of 197 participants (50% of whom were women) aged between 30 and 60 years and with overweight or obesity (i.e., body mass index ≥25.0 and <40.0 kg/m2) were randomly assigned to UC (49 participants), early TRE (49 participants), late TRE (52 participants), or self-selected TRE (47 participants). Participants in the UC group maintained their habitual eating window of ≥12 hours. Participants in the early TRE group started eating before 10:00, those in the late TRE group started after 13:00, and those in the self-selected TRE group chose their own 8-hour eating window. All participants maintained the same eating window throughout the 12-week intervention period.
VAT and Body Weight Reduction: Is TRE plus Mediterranean Diet More Effective than the Mediterranean Diet Alone?
Interestingly, we found that incorporating TRE, regardless of the eating window timing, into the UC intervention (Mediterranean diet nutritional education program) did not offer additional benefit over the UC alone for reducing VAT. However, early TRE led to a more pronounced reduction in abdominal SAT than the UC intervention. Regarding body weight, an 8-hour TRE regimen, irrespective of the timing of the eating window, resulted in greater body weight loss compared to the UC intervention. Notably, there were no differences in fat mass or fat-free mass between groups after the 12-week intervention. These findings highlight TRE as a promising nutritional strategy for body weight management in individuals with overweight or obesity.
The Impact of TRE on Glucose Homeostasis
In the present study, we also measured fasting glucose levels before and after the 12-week intervention, and monitored 24-hour glucose levels during a 14-day period prior to the intervention and during the final two weeks of the intervention. This comprehensive assessment provided deeper insights into daily glycemic homeostasis. We found that an early TRE schedule (i.e., 8-hour eating window in the early part of the day) presented reduced fasting glucose and nocturnal mean glucose levels compared to the UC intervention, and late and self-selected TRE schedules. Notably, the 24-hour and daytime glucose variability, as assessed by coefficients of variation, was higher in the early TRE schedule than in the late and self-selected schedules, while nighttime glucose variability was lower compared to the UC intervention. Further studies are needed to determine whether an early TRE schedule offers greater benefits for glucose homeostasis in adults with overweight or obesity.
TRE is a Safe Nutritional Strategy for Managing Cardiometabolic Health in Adults with Overweight or Obesity
Throughout the 12-week intervention, TRE adherence rates ranged from 85–88%, and no serious adverse events were reported, suggesting that TRE is a safe, well-tolerated strategy for people with overweight or obesity.
For more information: Dote-Montero, M., Clavero-Jimeno, A., et al. Effects of early, late and self-selected time-restricted eating on visceral adipose tissue and cardiometabolic health in participants with overweight or obesity: a randomized controlled trial. Nat Med (2025). https://doi.org/10.1038/s41591-024-03375-y
The poster image was created by Raquel Sevilla Lorente, @dopaminty
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