Less calorie intake may be more effective than intermittent fasting – study
Intermittent fasting, also known as time-restricted eating patterns, has gained popularity among health-conscious people looking to lose weight naturally. However, according to a six-year study published in the Journal of the American Heart Association (AHA), timing from first meal to last meal was not associated with weight loss, but the frequency and size of meals were.
The study, which was supported by an American Heart Association Strategically Funded Research Network Grant to Johns Hopkins University School of Medicine, examined the electronic health records of approximately 550 adults aged 18 and older who were followed for six years. It went on to say that eating fewer large meals and eating less overall may be a more effective weight-loss strategy than restricting meals to a specific time window, such as intermittent fasting.
Although intermittent fasting is popular, rigorously designed studies have not yet determined whether limiting the total eating window during the day helps to control weight, according to senior study author Wendy L. Bennett, MD, MPH, an associate professor of medicine at Johns Hopkins University School of Medicine in Baltimore.
This study looked at the relationship between the time between meals and weight change. Participants in the study had at least one weight and height measurement taken in the two years preceding the enrolment period, which ran from February to July 2019.
The research team developed Daily24, a mobile application that allows participants to track their sleeping, eating, and waking times for each 24-hour window in real time. Participants were encouraged to use the app as much as possible during the first month and again during “power weeks” — one week per month for the six-month intervention portion of the study.
Researchers were able to measure the time from the first meal to the last meal each day, the time lapse from waking to the first meal, and the interval from the last meal to sleep based on the timing of sleeping and eating each day recorded in the mobile app. They calculated an average for each participant based on all data from completed days.
During the six-year follow-up period, meal timing was not associated with weight change, according to the data analysis. Over a six-year period, the total daily number of large meals (estimated at more than 1,000 calories) and medium meals (estimated at 500-1,000 calories) were both associated with increased weight, while fewer small meals (estimated at less than 500 calories) were associated with decreased weight.
The average time between the first and last meal was 11.5 hours; the average time between waking up and the first meal was 1.6 hours; the average time between the last meal and sleep was 4 hours; and the average sleep duration was 7.5 hours.
The study found no link between meal timing and weight change in a population with a wide range of body weight.
According to Bennett, while previous research has suggested that intermittent fasting may improve the body’s rhythms and regulate metabolism, this study in a large group with a wide range of body weights did not establish this link. Large-scale, rigorous clinical trials of intermittent fasting on long-term weight change are extremely difficult to conduct; however, even brief intervention studies may be useful in guiding future recommendations.
According to lead study author Di Zhao, PhD, an associate scientist in the division of cardiovascular and clinical epidemiology at Johns Hopkins Bloomberg School of Public Health, while meal frequency and total calorie intake were found to be stronger risk factors for weight change than meal timing, the findings could not prove direct cause and effect.
The study has limitations, according to the researchers, because it did not evaluate the complex interactions of timing and frequency of eating. Furthermore, because the study was observational in nature, the authors were unable to determine cause and effect. Future studies should aim to include a more diverse population, as the majority of the study’s participants were well-educated white women from the US’s mid-Atlantic region, the authors wrote.
Researchers were also unable to determine whether study participants intended to lose weight prior to enrolment and could not rule out the possibility of any pre-existing health conditions.
The study concluded that the number of daily meals was related to weight change over a six-year period. In addition, the findings did not support the use of time restricted eating as a long-term weight loss strategy in a general medical population.
