One of the most interesting diet trends of recent years has been disproved.
A new study has found that intermittent fasting – a celebrity-favorite diet where eating is limited to a window of about 8 hours during the day – doesn’t help people lose weight and can even result in muscle loss.
The study by researchers at the University of California at San Francisco (UCSF) found that those who fasted intermittently for 12 weeks lost only half a pound more than a group of people who ate normally. Previous diet studies promised a range of benefits, from weight loss to longevity; however, much of the research has only studied mice.
The new findings, published in JAMA Internal Medicine following a clinical study, were shocking to researchers, one of whom was also on a diet himself for seven years.
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It spills years of hype, especially among Silicon Valley biohacking types, who touted fasting as a way to stay healthy, be productive, and live longer. Among his most loyal devotees was Twitter CEO Jack Dorsey. But even the average Joes has combined it with healthier lifestyle choices for losing weight. Last year, a version of it was the most searched dietary trend of the year.
In reality, however, it was found that no one on diet alone loses a statistically significant amount of weight, according to the study, which enrolled 116 overweight or obese participants. It also had little effect on blood sugar and cholesterol levels.
In fact, it has also had some negative effects. Some of the diet participants actually experienced loss of lean muscle mass, the study found.
Previous research promoting the weight loss benefits of intermittent fasting had come with the caveat that any resulting fat loss could have more to do with calorie restriction, since fewer hours of consumption per day generally meant fewer opportunities to exaggerate.