Eating all meals between 7am and 3pm at least five days per week can drive weight loss while lifting a person’s mood and energy levels, according to a study in people who are obese.
Intermittent fasting is an increasingly popular weight-loss tool. One example is the 16:8 diet, which involves eating within an 8-hour window and fasting for the remaining 16 hours of the day.
To test how well the 16:8 approach works, at the University of Alabama at Birmingham and her colleagues invited 90 adults with a body mass index of more than 30, defined as obese, to receive advice on how to cut their calorie intake and be more active.
Advertisement
Half of the participants were also randomly assigned to eat all their meals between 7am and 3pm for at least five days per week for 14 weeks, while the rest were assigned to eat over a period of 12 or more hours per day.
Nearly 40 per cent of those in the intermittent fasting group adhered to the diet, with these participants losing an average of 7.6 kilograms. In contrast, the participants in the control group lost an average of 3.9 kilograms.
Based on questionnaires completed before and after the trial, the intermittent eaters also reported greater boosts to their mood and reductions in anger than the control group.
Weight loss didn’t always correlate with mood improvement, however, which suggests that this can’t just be explained by the fasting participants being happy about losing weight, says Peterson. “Our analysis suggests there was something physiological going on as well to explain their improved mood, but we don’t know what that is yet,” she says.
The intermittent fasting group also reported sleeping 30 minutes less on average per day than the control group, but paradoxically felt less tired. “At first, I was worried it was messing up people’s sleep because they were hungry at night, but we didn’t find evidence of that,” says Peterson. “Maybe the longer fasting period gives your body more time to rest and repair [while awake] so you need less sleep at night, which we think is an exciting angle.”
leads to weight loss. The latest trial may have shown a clear benefit due to it combining intermittent fasting eating with advice on how to reduce calories, says at the University of Adelaide, Australia.
It may also have been more successful than others because the 8-hour eating period started relatively early in the morning, says Peterson. Accumulating evidence suggests that .
The diet’s 40 per cent adherence rate suggests that some people may find it more challenging to follow than others, says Heilbronn.
Other fasting diets like the 5:2 plan, which involves drastically cutting calorie intake for two days per week, often show promise in the first few months but many people find it hard to follow for a long time, she says.
Peterson and her colleagues aren’t planning a long-term follow-up of their trial participants, but 42 per cent of the individuals in the intermittent fasting group said they planned to continue only eating between 7am and 3pm after the trial ended.
Obesity
