New research published in the Journal of the American Heart Association found that the size and number of meals were more important for weight loss or gain than the time between the first and last meal.
At a Glance:
- Eating less overall and fewer big meals may be a better way to lose weight than eating only during a small window of time, like intermittent fasting.
- During the six-year study, the time between the first and last meals was not linked to the weight change.
Intermittent fasting has become a popular way to help people reach their weight loss goals, with an emphasis on eating within a certain timeframe and letting the body fast for the rest of the day. While intermittent fasting can help to reduce calorie intake, it is not necessarily the most effective way to lose weight.
The frequency and quantity of meals were a better predictor of weight loss or increase than the interval between the first and final meal, according to new research published online in the Journal of the American Heart Association, a peer-reviewed journal of the American Heart Association (Zhao et al., 2023).
Wendy L. Bennett, M.D., M.P.H., the lead author of the study and an associate professor at Johns Hopkins University School of Medicine in Baltimore, says that even though “time-restricted eating patterns” are popular, well-designed studies have not yet shown that limiting the total eating window may help lose weight.
The Study
The average age of the participants was 51, and their average body mass index was 30,8, which is considered obese. The average duration of weight-related follow-up in the electronic health record was 6,3 years.
The research team made a mobile app called Daily24 so that people could keep track of when they slept, ate, and woke up for each 24-hour window in real-time.
On the basis of the timing of sleeping and eating each day as recorded in the mobile app, researchers determined: the time between the first and final meal each day, the time between waking and the first meal, and the time between the last meal and sleep.
The data analysis found:
- During the six-year follow-up, the time of meals was not linked with weight loss. This comprises the time between meals, from waking up to eating, from eating to sleeping, and total sleep time.
- Over the six-year follow-up, eating more big meals (>1,000 calories) and medium meals (500-1,000 calories) increased weight, but eating fewer small meals (<500 calories) decreased weight.
- The average period was 11.5 hours from first to last meal, 1.6 hours from waking up to the first meal, 4 hours from the final meal to sleep, and 7.5 hours as calculated for sleep.
In the study population with a wide variety of body weights, the study failed to find a relationship between meal timing and weight change.
According to expert opinion, we can explain why reducing total calories is usually more effective than intermittent fasting alone.
The observation—total overall caloric intake is the major driver of weight gain, and not the timing—lies on the fundamental mechanism of obesity and overweight—an imbalance between calorie intake and calorie expenditure.
Obesity occurs when a person consumes more energy from food than is used in physical activity or any other metabolic process. This causes an excess of energy to accumulate in the form of body fat.
Therefore, reducing total calorie intake is important. However, intermittent fasting often leads to unhealthy eating patterns as one may be tempted to cram as much food into the eating window as possible.
According to Bennett, this study in a big sample with a wide variety of body weights did not find a connection between intermittent fasting and better body rhythms and metabolic regulation.
The study had limitations, according to the researchers, because it did not analyze the complicated interplay of time and frequency of eating. Furthermore, because the study was observational in nature, the scientists were unable to determine cause and effect.
Researchers were also unable to establish whether research participants intended to lose weight prior to recruitment and could not rule out the possibility of any previous health issues.
