Overweight and obesity are long-established modifiable risk factors for a number of cardiovascular diseases. Several behavioral approaches are commonly used to manage obesity, such as restricting calories, modifying diet composition, and increasing physical activity; however, these interventions have had limited success. “The gold standard for weight gain prevention and weight loss is to recommend that people reduce how much they eat and increase exercise,” says Wendy L. Bennett, MD, MPH. “However, many people struggle to maintain this advice.”
Research suggests the timing of food intake may regulate metabolic function and reduce body weight. “In animal studies, misaligned timing of eating relative to timing of sleeping (ie, circadian misalignment) has been associated with weight gain, but it’s more complicated in humans,” notes Dr. Bennett. “Little is known about whether the timing of eating windows—such as wake to first eating, total duration of eating, and last eating occasion to bedtime—is associated with weight change over time.”
Exploring Weight Changes Over Time
For a longitudinal cohort study published in the Journal of the American Heart Association, Dr. Bennett and colleagues evaluated longitudinal associations between time from first to last meal with weight trajectories over time using the Daily24 dedicated smartphone application. The analysis also explored associations between weight trajectories and time from wake to first meal, last meal to sleep, sleep duration, and the number of meals. “We wanted to look at weight change over time in people who are not necessarily trying to lose or change their weight,” Dr. Bennett adds.
The study included 547 adults who were recruited from three health systems. During the 6‐month study, participants downloaded and used a mobile app to record the timing of meals and sleep for at least 1 day. Researchers obtained information on weight and comorbidities at each outpatient visit from EHRs for up to 10 years before, and up to 10 months after, enrollment. Participants had an average age of 51.1, and average BMI of 30.8kg/m2, and most were women (77.9%) and reported White race (77.5%).
Time of Eating Not Related to Weight Change Over Time
“We found that the timing of eating—wake to first eating, total duration of eating, and last eating occasion to bedtime—was not associated with weight change over time,” says Dr. Bennett. During an average of about 6 years of follow‐up, the mean interval from a first to a last meal was 11.5 hours (Figure). The average daily number of large and medium meals was associated with increased weight over time. “In the app, participants reported on the approximate size of the meals they ate,” Dr. Bennett says. “Eating more small meals was associated with weight loss over time. However, eating more meals overall and eating greater quantities of larger or medium sized meals was associated with weight gain over time.”
The analysis also suggested that some dietary behaviors may be representative of long‐term dietary patterns and were associated with weight trajectories up to 10 years before the time of dietary measurements. For example, a greater number of meals per day was associated with weight gain. The average annual weight change associated with an increase of 1 daily meal was 0.28 kg.
Wanted: A Better Understanding of Circadian Misalignment Effects
Limiting the frequency of large meals is an important strategy when counseling patients about weight gain prevention. “Using time-restricted feeding—in which eating is limited to shorter windows to promote longer fasts—does not appear to be a successful strategy to limit weight gain or lose weight over time,” Dr. Bennett says. “On the other hand, reducing large meals may be an effective weight gain prevention strategy.”
More research is needed on the mechanisms of the observed associations between meal frequency and weight gain. “We need to determine if more intense periods of short-term fasting can lead to weight loss and whether it can be sustained,” explains Dr. Bennett. “Clinical trials that control for both caloric consumption and timing of eating are needed to disentangle their independent effects on weight and other health outcomes. Understanding the effects of circadian misalignment on metabolic changes is still an important area of future research. We also need to determine the best ways to advise people on the timing of their meals and the importance of sleep among those who work outside of normal business hours, such as shift workers.”
