A new study from a group of researchers in Spain investigated the effects of various intermittent fasting protocols on belly fat.
197 weight stable adults with overweight or obesity were split into one of the following groups:
- Early - 1st meal before 10am and last meal before 6pm (8 hour window)
- Late- 1st meal after 1pm and last meal before 9pm (8 hour window…h/t Martin Berkhan)
- Self- 8 hour eating window self selected
- Usual- no intermittent fasting
All subjects were counseled to follow a Mediterranean dietary pattern in addition to exercise (subjects were insufficiently active prior to the study). Belly fat, i.e. Visceral Adipose Tissue (VAT) was measured by MRI, which is a very accurate way to measure body composition.
After 12-weeks, belly fat decreased in all groups, with no difference compared to the usual care group and no differences between groups.
While there are many different types of Time Restricted Feeding (TRE), e.g. a 16:8 ratio where an individuals fasts for 16 hours and consumes all daily calories within 8 hours, alternate day fasting where people eat one day and fast the next to achieve a particular calorie level over the course of the week, and so on, none of them seem to offer an advantage for weight loss, body composition, or health.
Some exceptions apply of course, as any dietary practice that improves adherence to a Calorie restricted diet is going to work well. Additionally, those with insulin resistance, e.g. metabolic syndrome and type 2 diabetes, may benefit from an “Early” TRE pattern, though data on this is limited.