The 16:8 approach has become one of the most popular forms of intermittent fasting.
It means eating within an 8-hour period each day and fasting for the remaining 16 hours.
But is there really something special about 8 hours?
Time-restricted eating can have health benefits
Research shows that limiting eating to a defined period of the day can lead to modest improvements in body weight and several measures of metabolic health, including blood sugar regulation.
This means that time-restricted eating is more than simply an internet trend.
But that does not mean that 16:8 is the only — or necessarily the best — way to do it.
Is 8 hours the ideal eating window?
Research has not established an ideal number of hours.
Studies have tested different eating windows, including periods shorter and longer than 8 hours.
When researchers compared these different approaches, the results did not consistently show that an 8-hour window was better than other time-restricted eating schedules.
So the popular 16:8 rule should not be interpreted as a scientifically established optimal formula.
Something else may matter: when the 8 hours occur
An important pattern is emerging from research.
The time of day when food is eaten may matter as much as the length of the eating window.
Earlier eating schedules generally appear more favorable for metabolic health than schedules that extend eating later into the day.
This fits with the body’s natural daily rhythms, which influence glucose metabolism, hormones, digestion and many other physiological processes.
So an eating window from morning to late afternoon may not have the same metabolic effects as an equally long window extending late into the evening.
For healthy aging, the question may therefore be broader than simply:
“How many hours should the eating window last?”
It may also be:
“When during the day should those hours occur?”
