Diet intermittent fasting

Diet intermittent fasting image (© SASITHORN -

CHICAGO — Intermittent fasting has been a popular weight loss strategy in recent years, but it has also been linked to several concerning health risks. While some concerns have been backed up by science, others have been more rumor than fact. Now, a new study is debunking several of these common myths about fasting to lose weight.

Researchers from the University of Illinois Chicago targeted four common warnings people who try intermittent fasting often encounter. Those include fasting leading to poor dieting habits, eating disorders, decreasing muscle mass, and diminished sex drive. By analyzing previous studies on the effects of intermittent fasting, the review in Nature Reviews Endocrinology was able to disprove all four potential pitfalls of fasting for health purposes.

“I’ve been studying intermittent fasting for 20 years, and I’m constantly asked if the diets are safe,” says lead author Krista Varady, a professor of kinesiology and nutrition at UIC, in a media release. “There is a lot of misinformation out there. However, those ideas are not based on science; they’re just based on personal opinion.”

There Are 2 Main Types of Intermittent Fasting

Researchers say that their findings apply to both types of popular fasting strategies dieters use to shed excess weight — alternate-day eating and time-restricted eating.

  • Alternate-day eating involves eating only a small number of calories one day and then eating whatever you want the next.
  • Time-restricted eating allows dieters to only eat within a four to 10-hour window each day.

Key Results: What Did Scientists Debunk?

Intermittent fasting does not lead to poor dieting habits:

The study finds that sugar, saturated fat, cholesterol, fiber, sodium, and caffeine levels do not change during periods of fasting in comparison to the time before a fast. Researchers also discovered that the percentage of energy consumed in the form of carbohydrates, protein, and fat does not change as well.

Intermittent fasting does not cause eating disorders:

None of the studies analyzed by the UIC team showed a link between people engaging in intermittent fasting and those dieters later developing an eating disorder. However, the study authors note that all of the studies they reviewed screened out anyone who previously had an eating disorder.

The researchers also urge people who have had a history of eating disorders to avoid intermittent fasting.

Intermittent fasting does not cause dramatic muscle mass loss:

The analyzed studies found that people lose the same amount of lean muscle mass by fasting as they do by engaging in another type of diet. In both cases, the team recommends resistance training and consuming more protein to prevent losing muscle. 

Intermittent fasting does not affect sex hormones:

Despite warnings that intermittent fasting could impact fertility and libido, the researchers did not find any link between estrogen, testosterone, or other sex-related hormones and shifting levels due to fasting.

About Chris Melore

Chris Melore has been a writer, researcher, editor, and producer in the New York-area since 2006. He won a local Emmy award for his work in sports television in 2011.

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