Commentary: Intermittent fasting – how and when to restrict food consumption is crucial

Work in 2022 showed no difference in terms of weight loss between opting for early- or late-morning eating. It did, however, have an effect on appetite during the day – this time to the advantage of the former.

And beyond the time of day when it seems preferable to eat, other factors may be at work that are not always measured in the studies carried out, including the quality and quantity of food absorbed, duration of the fasting period (which can extend from 12 hours to 20 hours per day). It is also worth remembering every individual has his or her own metabolism and may respond differently to fasting.

New, better controlled and more comprehensive studies are therefore needed to confirm the potential benefits of these methods and to understand the mechanisms involved in their effects.


The most suitable method to avoid disrupting one’s circadian clock (and thereby limiting the risk of frustration or eating disorders) appears to be time-limited food intake by synchronizing meals with circadian rhythms.

Thus, a typical day could be organized with a hearty breakfast in the morning taking place between 6am and 8am, a lunch around noon and finally bringing dinner forward so that it takes place between 4pm and 6pm, depending on the season.

This is not necessarily easy to reconcile with one’s social life. It can be complicated to practice intermittent fasting for a family, when one practices a sporting activity in the early evening or when one works in the evening until 7pm or 8pm.

One solution would be to opt for a big breakfast and not too caloric a meal in the evening – preferably without carbohydrates or sugars, so as not to risk shifting one’s biological clock.

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