Alternate-day fasting (ADF) is known as one of the “most extreme diet interventions” in the weight loss community. Despite being highly restrictive, the diet has been found offering a number of health benefits, from longer lifespan, reduced cholesterol levels to lower belly fat.
Researchers said their study is the largest of its kind to explore the effects of ADF. The diet requires people to fast for 36 hours and eat anything they want for 12 hours.
“Strict ADF is one of the most extreme diet interventions, and it has not been sufficiently investigated within randomized controlled trials,” Frank Madeo, a professor at Karl-Franzens University of Graz in Austria, said. “In this study, we aimed to explore a broad range of parameters, from physiological to molecular measures.”
The new study, published in the journal Cell Metabolism, analyzed the health of 60 people who were asked to follow either ADF or another controlled diet. All participants started healthy and with normal weight.
Researchers asked each person to undergo continuous glucose monitoring during the study and to detail their food consumption in diaries to avoid consumption of extra calories during fasting days.
Another 30 people later joined the study. This group followed ADF for more than six months prior to the experiment.
Researchers then compared data on both groups to see the short- and long-term effects of fasting.
“We found that on average, during the 12 hours when they could eat normally, the participants in the ADF group compensated for some of the calories lost from the fasting, but not all,” Harald Sourij, a professor at the Medical University of Graz, said. “Overall, they reached a mean calorie restriction of about 35% and lost an average of 3.5 kg [7.7 lb] during four weeks of ADF.”
The participants on ADF showed lower amino acids and the hormone triiodothyronine, which both were linked to lifespan extension, MedicalXpress reported Tuesday. Fasting also helped reduce sICAM-1 that has been associated with age-related conditions and inflammation.
The other benefits of ADF found in the study are reduced levels of cholesterol and belly fat. However, researchers noted it is too early to recommend the fasting approach to the public.
They said more studies are required to understand the long-term effects of ADF as a daily practice. Researchers aim to analyze the diet in the future with people with obesity and diabetes, and to compare it to other dietary interventions.