Intermittent Fasting May Not Be As Effective for Weight Management As Limiting Calorie Intake

Meal size and frequency appears to have a greater impact on weight management than time between first and last meal, according to research published in the open access Journal of the American Heart Association. However, consuming fewer total calories and fewer large meals (1000 calories or more) were associated with better weight management, as shown in a 6-year study of 550 adults from 3 health systems in Maryland and Pennsylvania.

Further, the large-scale study did not detect a link between intermittent fasting and a more regulated metabolism, explained Wendy L. Bennett, MD, MPh, an associate professor of medicine at Johns Hopkins University School of Medicine in Baltimore, in a press release.

Data from the American Heart Association (AHA) suggest that 40% of US adults are obese, which can negatively impact cardiovascular health and contribute to other serious conditions. To investigate this area further, investigators in the current study looked to address a difficult-to-answer question about intermittent fasting and long-term weight change.

The investigators studied the association between meal timing and weight change and enrolled individuals with accessible electronic health records. Participants were majority White at 80%; among patients, 12% self-reported as Black and 3% self-identified as Asian. The average participant was aged 51 years with a college education and considered obese, having an average body mass index (BMI) of 30.8.

The investigators created the Daily24 app—in which participants logged sleeping, eating, and wake-up time in 24-hour windows—and based on their data, measured: the time from the first meal to the last meal each day, time lapse from waking to first meal, and the interval from the last meal to sleep.

Fewer smaller meals that are averaged below 500 calories were associated with patients maintaining a lower weight compared to those who ate medium to large meals (500 to 1000 calories). During the 6-year follow-up, meal timing was not associated with weight change, with considerations made for various body weights. In fact, adults who did not restrict eating time had less weight gain and better control of their diet.

The investigators noted that there are limitations to the study. First, investigators did not evaluate how timing and meal frequency interact, nor could they conclude cause and effect. Additionally, the team could not determine whether patients had a goal of weight loss at the study onset. Further, investigators emphasized a need for future studies to include a more diverse cohort.

According to Di Zhao, PhD, an associate scientist in the division of cardiovascular and clinical epidemiology at Johns Hopkins Bloomberg School of Public Health, current AHA guidelines do not recommend smaller and more frequent meals for weight loss, and the study did not demonstrate that this diet was helpful for weight management,

Reference

American Heart Association. Reducing total calories may be more effective for weight loss than intermittent fasting. News Release. January 18, 2023. Accessed January 18, 2023. https://www.eurekalert.org/news-releases/976731