A 15-month medication trial involving over 2,000 patients revealed average weight loss of 15 kg.
According to recent studies, the frequency and size of meals are better indicators of weight gain or loss than the time between meals. The study’s results were published in the open-access, peer-reviewed Journal of the American Heart Association, a publication of the American Heart Association.
Although while “time-restricted eating patterns” or intermittent fasting are well-liked, principal study author Wendy L. Bennett, M.D., M.P.H. claims that rigorously planned trials have not yet established whether restricting the whole eating window during the day aids in weight control.
This study assessed the relationship between weight change and the interval between the first and last meals. The study included over 550 participants (18 years of age or older) from three health systems with electronic health records in Maryland and Pennsylvania. In the two years before study enrolment, participants had at least one weight and height assessment recorded.
In depth analysis into intermittent fasting and weight loss
The majority of participants (80%) were white adults; 12% Black adults; and roughly 3% Asian adults. The majority of participants claimed to have a bachelor’s degree or higher; the average participant was 51 years old; and the average body mass index was 30.8, which is regarded as being obese. The electronic health record’s weight data had an average follow-up period of 6.3 years.
In comparison to the adults who had a lower body mass index, participants with a higher BMI were more likely to be Black adults, older, have Type 2 diabetes or high blood pressure, have a lower education level, exercise less, eat fewer fruits and vegetables, and have a longer time between the last meal and sleep and a shorter time between the first and last meal.
The study team developed the mobile app Daily24 so that participants could report their sleeping, eating, and waking up schedules for each 24-hour period in real-time. Participants were urged to use the app as much as possible during the first month and again during “power weeks” via emails, texts, and in-app notifications.
Researchers were able to gauge the intervals between the first and final meals consumed each day, the time between awakening and the first meal, and the time between the last meal and going to bed based on the timing of sleeping and eating each day that was recorded in the mobile app.
For every participant, they produced an average based on all the completed day data. During the six-year follow-up period, meal timing was not related to weight change. This spans the time from the first to the final meal, from waking up to the first meal, from the last meal to going to sleep, and the overall amount of sleep.
No link between meal timing and weight loss
Over the course of a six-year follow-up, eating more large meals (estimated to contain more than 1,000 calories) and medium meals (estimated to contain 500–1,000 calories) was linked to weight gain, whereas eating fewer small meals (estimated to contain less than 500 calories) was linked to weight loss.
The average amount of time between the first and last meals was 11.5 hours; the average amount of time between waking up and the first meal was 1.6 hours; the average amount of time between the last meal and bedtime was 4 hours; and the average amount of time spent sleeping was 7.5 hours.
In a group with a wide variety of body weights, the study was unable to find a correlation between meal timing and weight change.
According to Bennett, this study in a big group with a wide range of body weights did not find a connection between intermittent fasting and better body rhythms and metabolism regulation.
Even short-term intervention studies may be helpful to inform future recommendations because it is extremely difficult to conduct large-scale, meticulous clinical trials of intermittent fasting on long-term weight change.
Limitations of the study
Di Zhao, PhD, the study’s lead author noted that while the study found that meal frequency and total calorie intake were more significant risk factors for weight change than meal timing, the findings could not establish a direct cause and effect relationship.
Since they did not examine the intricate relationships between time and frequency of eating, researchers acknowledge that the study has limitations.
Furthermore, because the study was observational in design, the scientists were unable to draw any conclusions on cause and effect.