According to Bennett, MD, MPH, an associate professor of medicine at the Johns Hopkins University School of Medicine in Baltimore, although ‘time-restricted eating patterns’ — known as intermittent fasting — are popular, rigorously designed There are studies that have not yet determined whether limiting total eating periods during the day helps control weight.
This study evaluated the association between the timing of the first meal to the last meal with weight change. Nearly 550 adults (18 years or older) with electronic health records from three health systems in Maryland and Pennsylvania were enrolled in the study. Participants had at least one weight and height measurement registered in the two years preceding the study’s enrollment period (February–July 2019).
Overall, the majority of participants (80%) reported that they were white adults; 12% self-reported as Black adults; And about 3% identify as Asian adults. Most participants reported having a college education or higher; The mean age was 51 years; And the average body mass index was 30.8, which is considered obese. The median follow-up time for weight recorded in electronic health records was 6.3 years.
Participants with higher body mass index at enrollment were more likely to be black adults, older, have type 2 diabetes or high blood pressure, have lower education levels, exercise less, eat fewer fruits and vegetables, have longer time since last meal Stayed longer to sleep and shorter duration from first to last meal than adults with lower body mass index.
The research team created a mobile application, Daily24, for participants to list their sleeping, eating and waking times for each 24-hour window in real time. Email, text messages and in-app notifications encouraged participants to use the app as little as possible during the first month and again during “power weeks” – one per month for the six-month intervention portion of the study Week.
Based on sleep and eating times each day recorded in the mobile app, the researchers were able to measure: the time from the first meal to the last meal each day; the time from waking up to the first meal; And the interval from last meal to bedtime. They calculated the average of all the data across the full days for each participant. The data analysis found: Meal timing was not associated with weight change during the six-year follow-up period. This includes the interval from first to last meal, from waking up to first meal, from last meal to bedtime, and total sleep duration.
The total daily number of large meals (estimated at more than 1,000 calories) and moderate meals (estimated at 500–1,000 calories) were each associated with increased weight over the six-year follow-up, while fewer small meals (estimated at less than 500 calories) were associated with decreased weight. were associated with. The average time from first to last meal was 11.5 hours; The average time from waking up to the first meal was measured at 1.6 hours; The average time from last meal to bedtime was 4 hours; And the average sleep duration was calculated to be 7.5 hours.
The study did not find changes in meal timing and weight in populations with a wide range of body weights. As reported by Bennett, even though prior studies have suggested that intermittent fasting can improve body rhythms and regulate metabolism, this study in a large group with a wide range of body weights Couldn’t find this link. It is notoriously difficult to conduct large-scale, rigorous clinical trials of intermittent fasting on weight change over a long period of time; However, short-term intervention studies may also be valuable in helping to guide future recommendations.
Although the study found that meal frequency and total caloric intake were stronger risk factors for weight change than meal timing, the findings proved direct cause-and-effect, according to lead study author Di Zhao, PhD, an associate scientist. Could not Division of cardiovascular and clinical epidemiology at the Johns Hopkins Bloomberg School of Public Health.
The researchers note that the study has limitations because it did not evaluate the complex interaction of timing and frequency of eating. Additionally, since the study is observational in nature, the authors were unable to draw cause-and-effect conclusions. The authors noted, future studies should work toward including more diverse populations because most of the study participants were well-educated white women in the Mid-Atlantic region of the US. The researchers also were not able to determine weight loss motivation among study participants prior to their enrollment and could not rule out additional variables such as any preexisting health conditions.
According to 2022 data from the American Heart Association, 40% of adults in the US are obese; And the association’s current diet and lifestyle recommendations for reducing the risk of cardiovascular disease include limiting overall caloric intake, eating a healthy diet, and increasing physical activity.
2017 American Heart Association scientific statement: Timing and frequency of meals: implications for the prevention of cardiovascular disease does not provide a clear preference for frequent small meals or intermittent fasting. It was noted that unregulated patterns of total caloric intake appear to be less conducive to the maintenance of body weight and optimal cardiovascular health. And, altering meal frequency may not be useful for reducing body weight or improving traditional cardiometabolic risk factors.