Late Eating Habits Linked to Higher Body Fat and Poorer Metabolic Health in Women

Women who naturally prefer staying up late and eating later in the day may have higher body fat and less favorable metabolic health than early risers, according to a new study published in Frontiers in Nutrition.

Researchers found that healthy women with an evening chronotype—those who tend to go to bed and wake up later—consumed a larger proportion of their daily calories in the evening. This eating pattern was associated with higher total and abdominal body fat, as well as less favorable metabolic markers, compared with women who had morning or intermediate chronotypes.

The study analyzed data from 287 healthy European and Pacific New Zealand women aged 18–45 who participated in the PROMISE study. Participants were classified according to their natural sleep-wake preferences, after which researchers assessed dietary intake, meal timing, body composition, physical activity, sleep habits, and fasting blood biomarkers.

Women with an evening chronotype were generally younger, had higher body mass index (BMI), and showed greater accumulation of body fat, particularly around the abdomen. They also experienced greater "social jetlag"—the mismatch between biological and social schedules—than women with earlier chronotypes.

Blood analyses revealed that evening chronotypes had higher levels of triglycerides, insulin, leptin, and HbA1c, indicating less favorable glucose metabolism and hormonal regulation. Although their average HbA1c values remained within the normal range, these findings suggest an increased risk of future metabolic disorders.

The researchers also observed important differences in eating patterns. Women with morning or intermediate chronotypes consumed a larger share of their daily calories, protein, carbohydrates, and fat before 10 a.m., while evening chronotypes ate a greater proportion of their daily energy intake after 8 p.m. Late eaters also consumed more carbohydrates overall and tended to have diets lower in fiber, vitamins, minerals, and other nutrient-rich foods.

Among women with higher body fat or greater abdominal fat accumulation, evening chronotypes were especially likely to consume fewer calories and nutrients in the morning and more energy, carbohydrates, fats, and protein during the evening.

Despite similar overall calorie and macronutrient intake, evening chronotypes consistently showed less favorable body composition, suggesting that meal timing may influence metabolic health independently of total food intake.

However, the researchers caution that the study was observational and cannot determine whether eating late directly causes obesity or metabolic problems. Because most evening chronotypes in the study were Pacific women, while most morning and intermediate chronotypes were New Zealand Europeans, ethnicity, cultural eating habits, and socioeconomic factors may also have contributed to the findings.

The authors conclude that additional research is needed to determine whether aligning meal timing with the body's circadian rhythms could help improve metabolic health and reduce obesity risk.

Follow NEWS.am Medicine on Facebook and Twitter