Studies have reported that late eating is linked to poor glucose metabolism, higher body mass index (BMI), and increased body fat as a result of greater caloric intake and the consumption of highly processed foods. New York-Presbyterian and Columbia endocrinologist recently published a paper in Nutrition and Diabetes showing that people with obesity and prediabetes or type 2 diabetes who ate most of their calories after 5 p.m. had worse glucose tolerance independent of other factors, such as body weight and caloric intake. The findings support the concept that it is not just what a person eats and how much, but when they eat that can affect their metabolic health.
Below the study’s senior author, Blandine Laferrère, M.D., Ph.D., an endocrinologist in the Diabetes Research Center at NewYork-Presbyterian and Columbia, elaborates on the findings and addresses their implications for weight management and patients’ health.
Eating late or during a prolonged eating window is associated with weight gain, overweight, and obesity.
— Dr. Blandine Laferrère
Research Background
The association between late eating and obesity or overweight has long been known. Eating late or during a prolonged eating window is associated with weight gain, overweight, and obesity. People tend to eat more and are more likely to drink alcohol at night rather than at breakfast or lunch, so late eating is associated with greater caloric intake overall.
Researchers have been delving deeper into this relationship, scrutinizing the effects of late eating on hormones and other biological markers. The findings of a randomized controlled clinical trial published in 2022 by investigators in Spain showed that among two groups of people who were fed the same number of calories at different times of day, late eating increased hunger, altered appetite-regulating hormones, decreased waketime energy expenditure, and modified lipid metabolism in a way that promotes fat storage. In our study, we set out to see if the association with glucose metabolism persisted after controlling for potentially confounding variables.
Research Methods
Our study included 26 adults with obesity age 50-75 with diet- or metformin-controlled pre-diabetes or early-onset type 2 diabetes. Over a two-week period, study participants used an app that enabled them to log and take time-stamped photos of their meals. Late eaters were defined as consuming 45% or more of their calories after 5 p.m., and early eaters did not.
Both late and early eaters ate the same number of calories each day. Body fat was measured using quantitative magnetic resonance. On day 13, study participants went to NewYork-Presbyterian and Columbia and were fed a prescribed diet. The next day, they each had an oral glucose tolerance test.
Late eating is associated with poorer glucose tolerance and is not explained by a higher BMI or body fat, nor by greater caloric intake or worse diet composition. The data are pretty clear.
— Dr. Blandine Laferrère
Key Findings
We found that early and late eaters did not differ with regard to anthropometrics or daily energy intake, but late eaters consumed significantly more carbohydrates and fats after 5 p.m. Fasting glucose, insulin, and C-peptide did not differ between groups. Late eaters, however, exhibited higher glucose concentrations during the oral glucose tolerance test, even after adjusting for body weight, fat mass, energy intake, and diet composition. The glucose findings persisted even when participants with type 2 diabetes were excluded.
Our findings showing that late eating is associated with poorer glucose tolerance is not explained by a higher BMI or body fat, nor by greater caloric intake or worse diet composition. The data are pretty clear. These results will need confirmation in future studies and validation in a larger cohort. We are also conducting a study to analyze the effects of time-restricted eating on energy balance, with results expected in 2026.
Clinical Implications
I would urge physicians to assess the dietary behaviors of patients with obesity and prediabetes or diabetes. As physicians, we don’t often have time to do this. But at the very least, ask your patients about what they eat and what time they eat, and suggest they eat most of their calories earlier in the day. It’s not just about the calories they consume, but also when they consume them.
