A recent study has uncovered important insights into the relationship between meal timing and body weight, suggesting that adjusting eating habits may play a crucial role in weight management. Published in the International Journal of Behavioral Nutrition and Physical Activity, the research identifies two significant practices associated with a lower long-term body mass index (BMI): extending the overnight fasting period and having an early breakfast.
Conducted by the Barcelona Institute for Global Health (ISGlobal), which operates with support from the “la Caixa” Foundation, the study analyzed data from over 7,000 participants aged 40 to 65 involved in the GCAT | Genomes for Life project, led by the Germans Trias i Pujol Research Institute (IGTP).
In 2018, these individuals provided information on their weight, height, eating habits—including meal times—lifestyle choices, and socioeconomic status through detailed questionnaires. Five years later, in 2023, more than 3,000 participants returned for follow-up assessments, during which their measurements were recorded again, and additional questionnaires were administered.
Findings and Implications
The study’s findings align with previous research, indicating that extending the overnight fasting window could contribute to maintaining a healthy weight, particularly when coupled with an early dinner and breakfast. “We believe that eating earlier in the day aligns better with our circadian rhythms, enhancing calorie burning and appetite regulation,” stated Luciana Pons-Muzzo, a researcher at ISGlobal during the study and now affiliated with IESE Business School. “However, we must emphasize that it is premature to draw definitive conclusions, as more rigorous studies are necessary to substantiate these claims.”
Gender Disparities
The researchers also noted significant gender differences in the data. Women tended to have a lower BMI compared to men, demonstrating higher adherence to the Mediterranean diet, reduced alcohol consumption, and poorer mental health. Additionally, women were more likely to manage household responsibilities.
Using a statistical method called cluster analysis, the team identified a specific subgroup of men who typically ate their first meal after 2:00 PM and averaged a 17-hour fasting period. This group exhibited less healthy lifestyle choices, such as a higher likelihood of smoking and alcohol consumption, lower physical activity levels, and less adherence to the Mediterranean diet. Furthermore, these men had lower educational attainment and were more prone to unemployment, a trend not seen in any female groups studied.
Intermittent Fasting Insights
The research explored the effects of intermittent fasting, particularly overnight fasting. “Our findings indicate that some men practicing intermittent fasting by skipping breakfast did not experience weight loss benefits,” noted Camille Lassale, ISGlobal researcher and senior co-author. “Other studies involving participants with obesity have shown that this approach is not more effective than simply reducing calorie intake for long-term weight management.”
This study contributes to the evolving field of “chrononutrition,” which examines the timing and frequency of food intake in relation to dietary patterns. Anna Palomar-Cros, another researcher at ISGlobal during the study, explained, “Unusual eating patterns can disrupt our circadian system, which governs physiological processes tied to the cycles of day and night.”
Previous Research Connections
This investigation builds on ISGlobal’s ongoing research into chrononutrition. Recent studies have indicated that early dinner and breakfast times are associated with a reduced risk of cardiovascular diseases and type 2 diabetes, reinforcing the potential health benefits of mindful meal timing.
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