New studies shine light on long-term effects of intermittent fasting

Two new studies are offering insights into the long-term effects of intermittent fasting on human health. The research suggests fasting for just one day a month over many years can lengthen lifespan and enhance cardiovascular health, but as always, the new studies are riddled with caveats.

Fasting diets are undeniably all the rage these days. From the conservative 5:2 diet to more extreme multi-day fasting strategies, the anecdotal health benefits of these diets seem impossible to ignore. A burgeoning body of research is slowly uncovering the underlying biological mechanisms behind the effects of these diets but there is still a great deal scientists do not understand.

And one of those key unanswered questions surrounds the long-term effects of fasting diets on the human body. While there have been a number of animal studies exploring the biological effects of fasting, and several short-term human studies looking at the acute effects, scientists do not know what happens to a human body when it consistently undergoes intermittent fasts over several years.

To try to tease out the long-term effects of fasting on a human body, a team of scientists from Intermountain Healthcare Heart Institute in Salt Lake City, Utah, tracked over 2,000 patients for nearly five years. The patients were enrolled into the study during the course of a cardiac catheterization procedure, and then followed for several years to ascertain long-term cardiovascular health and overall mortality.

The unique part of the research was the fact that a large portion of the cohort were members of the Church of Jesus Christ of Latter-day Saints. One typical behavior of the church is to fast for up to 24 hours across the first Sunday of every month. While not all modern Latter-day Saints regularly engage with what many call “Fast Sunday,” the research was able to home in on 389 subjects in the cohort reporting routine monthly fasting for over five years.

Benjamin Horne, one of the researchers working on the project, says the results were more profound than anyone expected. After five years of follow-ups, those routine monthly fasters revealed a 45 percent lower mortality rate than the non-fasters.

“It’s another example of how we’re finding that regularly fasting can lead to better health outcomes and longer lives,” says Horne.

A second investigation into the long-term effects of fasting on myocardial infarction (MI) and heart failure (HF) revealed interestingly discordant results. The data showed no difference in incidences of myocardial infarction (otherwise known as a heart attack) between the fasters and non-fasters. However, the fasting group strikingly revealed a 71 percent lower rate of heart failure compared to the non-fasters.

“We think that long-term fasting of about one day, once a month, over a period of decades is making the body activate those beneficial mechanisms for a few hours each day between dinner and breakfast when it usually wouldn’t,” says Horne. “Those hours build up over long periods of time and provide the benefits.”