Intermittent Fasting Diets Could Increase Risk of Heart Disease: Study

Researchers indicate short-term benefits of the diet do not negate the negative side effects of intermittent fasting, which may increase the risk of heart disease.

In recent years, intermittent fasting has been touted by many as a key to weight loss, encouraging dieters to restrict their consumption of food to a limited time-window, to promote weight loss. However, the findings of a new study suggest that side effects of intermittent fasting may actually significantly increase a person’s risk of death from heart disease.

According to findings presented earlier this week at the American Heart Association’s scientific sessions in Chicago, following an 8-hour time-restricted eating schedule increased a person’s risk of death from cardiovascular disease by 91%.

Intermittent fasting has been shown to be an effective weight-loss method, requiring individuals to only consumer food or calories during a period between a six to ten hour period of the day, or alternating days where no food is consumed. This compares to a typical diet, where food is consumed across 16 or more hours each day. The diet is intended to allow followers to not feel deprived of eating what they want to during their eating windows, but usually it results in less total caloric intake throughout the day, since they are only consuming food for a limited period of time.

The new study reviewed dietary pattern data of participants in the annual 2003–2018 National Health and Nutrition Examination Surveys, and compared the information to data from the U.S. Centers for Disease Control and Prevention’s National Death Index database of people who died in the U.S. from 2003 to 2019.

The study included information for more than 20,000 U.S adults who followed a 16:8 intermittent fasting schedule, with only eight hours of eating and 16 hours of fasting.

Compared to the standard schedule of eating across 16 hours in a day that most people naturally follow, intermittent fasting increased a person’s risk of dying from heart disease by 91%.

People who already had heart disease and did the intermittent fasting schedule between eight and ten hours faced a 66% increased risk of death from heart disease or stroke, the researchers determined.

Intermittent fasting did not reduce the overall risk of death from any cause. In fact, following an eating duration of more than 16 hours per day was linked with a lower risk of cancer death among people already diagnosed with cancer.

Intermittent Fasting Benefits Did Not Pan Out

Many people say they like intermittent fasting because it helps with weight loss. Prior research indicated it may help lower blood pressure and reduce blood glucose levels. But, the new research indicates intermittent fasting did not improve the risk of heart disease and was not linked to living longer.

Researchers said the diet has many short-term benefits, but in the long run, there may be more negative side effects of intermittent fasting. This is especially important for patients with preexisting heart conditions or cancer to be aware of.

The study did not establish a cause and effect relationship between intermittent fasting and heart disease, but indicated an association. The study authors said more research is needed to examine the nutrient quality of the diets typical of intermittent fasting participants and to determine if that plays a role in increasing the risk of heart disease.

Researchers also recommend a cautious and personalized approach to dietary recommendations from doctors instead of blanket recommendations. The diet should align with a person’s health conditions and preexisting conditions, as well as focus on the latest scientific evidence.

The research was presented at the American Heart Association’s Epidemiology and Prevention | Lifestyle and Cardiometabolic Scientific Sessions 2024 on March 18-21 in Chicago. Findings presented at a conference are considered preliminary until published in a peer-reviewed journal.