Time-restricted eating, reducing the number of meals eaten in a day, and getting more calories earlier in the day all seem to be effective weight-loss strategies, according to a new systematic review published today.
Scientists at the University of Bond, Australia, brought together and reanalyzed data from 29 previous clinical trials of those three dietary interventions, all of which compared them with control groups who were given standard care or nutritional advice.
Scientists found that all three interventions helped participants lose a significant amount of weight, just by changing the timings of when they ate, rather than the contents of their diets.
The scientists wrote that recently there had been increased interest in “meal-timing strategies”—more commonly known as intermittent fasting—where people change the “when” rather than the “what” of their diets to lose weight.
Time-restricted eating involves shortening the window of time in which eating occurs throughout the day; for example, to eight hours, with the remaining 16 hours left for fasting.
Nutrition experts say this gives the body’s digestive system a break, so the body can focus on other functions. It may also result in ketosis, where the liver creates ketones as energy from fat cells, rather than relying on dietary sugars for fuel.
Reducing the number of meals per day, or skipping meals, may have the same effect as time-restricted eating, giving the body a longer fasting window.
And, choosing to eat more calories earlier in the day may be an effective weight-loss strategy because that is when the digestive system is most effective at processing food—especially sugar—and using it for fuel rather than storing it.
An image of a clock, knife and fork on a plate. Intermittent fasting, where dieters change when they eat rather than what, can be done in a variety of ways.
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Investigating data from 2,485 participants in 12-week randomized controlled trials, the Bond scientists found that all three strategies were effective for weight loss—but that reducing the number of meals eaten per day seemed to be the most effective of the three.
Front-loading calories to the morning produced results that were almost as good, and time-restricted eating was the least effective for weight loss of the three—according to the scientists’ analyses.
In total, the meta-analysis included 17 studies on time-restricted eating, eight studies on meal frequency, and only four studies on calorie distribution.
However, the scientists did write that there were some concerns over their results. For a start, of the 29 studies they included, they wrote that they had “high concerns” about the risk of among 22 of them. They added that, for some of the studies they included, the scientists who ran the research had been inconsistent in their methods.
And they called for further research to be conducted, on bigger groups of people, and for longer periods of time, to investigate the true efficacy of these methods.
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Reference
Liu, H. Y., Eso, A. A., Cook, N., O’Neill, H. M., Albarqouni, L. (2024). Meal Timing and Anthropometric and Metabolic Outcomes: A Systematic Review and Meta-Analysis, JAMA Network Open 7 (11): e2442163. https://doi.org/10.1001/jamanetworkopen.2024.42163