Reducing Total Calories May Be More Effective for Weight Loss than Intermittent Fasting

This study evaluated the association between time from the first meal to last meal with weight change. Nearly 550 adults were enrolled in the study.

Participants had at least one weight and height measurement registered in the two years prior to the study’s enrollment period.

Overall, most participants (80%) reported they were white adults; 12% self-reported as Black adults; and about 3% self-identified as Asian adults. Most participants reported having a college education or higher; the average age was 51 years; and the average body mass index was 30.8, which is considered obese. The average follow-up time for weight recorded in the electronic health record was 6.3 years.

The research team created a mobile application, Daily24, for participants to catalog sleeping, eating and wake up time for each 24-hour window in real time. 

They calculated an average for all data from completed days for each participant.

The data analysis found:

  • Meal timing was not associated with weight change during the six-year follow-up period. This includes the interval from first to last meal, from waking up to eating a first meal, from eating the last meal to going to sleep and total sleep duration.
  • The study did not detect an association meal timing and weight change in a population with a wide range of body weight.

Although ‘time-restricted eating patterns’ — known as intermittent fasting — are popular, rigorously designed studies have not yet determined whether limiting the total eating window during the day helps to control weight, says Wendy L. Bennett, M.D., M.P.H.

Researchers note there are limitations to the study since they did not evaluate the complex interactions of timing and frequency of eating. Additionally, since the study is observational in nature, the authors were unable to conclude cause and effect. Future studies should work toward including a more diverse population, since the majority of the study’s participants were well-educated white women in the mid-Atlantic region of the U.S., the authors noted author.


Di Zhao, Eliseo Guallar, Thomas B. Woolf, Lindsay Martin, Harold Lehmann, Janelle Coughlin, Katherine Holzhauer, Attia A. Goheer, Kathleen M. McTigue, Michelle R. Lent, Marquis Hawkins, Jeanne M. Clark, Wendy L. Bennett. Association of Eating and Sleeping Intervals With Weight Change Over Time: The Daily24 Cohort. Journal of the American Heart Association, 2023; DOI: 10.1161/JAHA.122.026484

American Heart Association. “Reducing total calories may be more effective for weight loss than intermittent fasting.” ScienceDaily. ScienceDaily, 18 January 2023. <>.

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Photo by Kirill Tonkikh