A randomised controlled trial study found that four weeks of strict alternate day fasting (ADF) improved markers of general health in healthy, middle-aged humans while causing a 37% calorie reduction on average. No adverse effects occurred even after six months.
Low-calorie diets work, but can be difficult to follow. Medical Xpress reports that a much simpler approach to losing weight might be to just stop eating every other day called alternate-day fasting (ADF). As the name implies, you starve yourself by fasting one day and then you feast the next, and then repeat that pattern again and again.
In just the month-long trial of the ADF diet, study volunteers lost more than seven pounds. That weight loss occurred even though people on the ADF diet ate about 30% more on the days they were allowed to eat than they normally would. Even with that extra food on feast days, the study volunteers still consumed fewer calories overall because of their fasting days, the researchers explained.
"This is an easy regimen – calculation of calories – and the compliance was very high," said the study's senior author, Frank Madeo, a professor of molecular biology at Karl-Franzens University of Graz, in Austria. Madeo said the researchers didn't study how the ADF diet might compare to other types of intermittent-fasting diets or to a more typical lower-calorie diet. He said that the ADF study didn't appear to have any impact on the immune system (at least in this short-term study), but that diets that simply rely on lower caloric intake may dampen immune system function.
"The reason might be due to evolutionary biology," Madeo suggested. "Our physiology is familiar with periods of starvation followed by food excesses." It's only in recent history that humans have had such an abundance of food that they need to restrict calories to maintain weight, he added.
In the new study, Madeo's team recruited 60 people, all healthy, non-obese adults. On average, they were just slightly overweight at the start of the study. Half of the study volunteers relied on an every-other-day fasting plan for a month. So, in a 48-hour period, they only ate during a 12-hour period. Eating during this time wasn't restricted. The other 30 people ate as they normally did without any restrictions.
Folks in the "fast and feast group" lost an average of 4.5% of their body weight. The group eating normally went up an average of less than a half pound. In addition to losing weight, the fast and feast group also saw healthy changes in heart disease risk factors, such as lower cholesterol, according to the study authors.
Despite these positive findings, the researchers aren't yet recommending ADF diets for everyone because the long-term effects of this diet aren't known.
Registered dietician Samantha Heller from NYU Langone Health in New York City said that although people lost weight, a diet where you fast every other day would be difficult to maintain. "What if you want to exercise? What if you have a physically active job? Our bodies are OK with not eating for a while, but they're happier when we have a consistent source of healthy foods to provide nutrients needed to accomplish the tasks we challenge our bodies with every day," she said.
Plus, Heller added that it's important to learn how to improve your lifestyle. "Someone who loses weight by fasting every other day won't learn strategies for living a healthy life. You need to create a healthy eating pattern that you can live with."
One simple change people can make would be to extend the natural intermittent fast everyone already does while they sleep. "For many people, after dinner is when they sit in front of the computer or TV and snack. So, close the kitchen after dinner," she suggested.
Abstract
Caloric restriction and intermittent fasting are known to prolong life- and healthspan in model organisms, while their effects on humans are less well studied. In a randomized controlled trial study, we show that 4 weeks of strict alternate day fasting (ADF) improved markers of general health in healthy, middle-aged humans while causing a 37% calorie reduction on average. No adverse effects occurred even after >6 months. ADF improved cardiovascular markers, reduced fat mass (particularly the trunk fat), improving the fat-to-lean ratio, and increased β-hydroxybutyrate, even on non-fasting days. On fasting days, the pro-aging amino-acid methionine, among others, was periodically depleted, while polyunsaturated fatty acids were elevated. We found reduced levels sICAM-1 (an age-associated inflammatory marker), low-density lipoprotein, and the metabolic regulator triiodothyronine after long-term ADF. These results shed light on the physiological impact of ADF and supports its safety. ADF could eventually become a clinically relevant intervention.
Authors
Slaven Stekovic, Sebastian J Hofer, Norbert Tripolt, Miguel A Aon, Philipp Royer, Lukas Pein, Julia T Stadler, Tobias Pendl, Barbara Prietl, Jasmin Url, Sabrina Schroeder, Jelena Tadic, Tobias Eisenberg, Christoph Magnes, Michael Stumpe, Elmar Zuegner, Natalie Bordag, Regina Riedl, Albrecht Schmidt, Ewald Kolesnik, Nicolas Verheyen, Anna Springer, Tobias Madl, Frank Sinner, Rafael de Cabo, Guido Kroemer, Barbara Obermayer-Pietsch, Jöm Dengjel, Harald Sourij, Thomas R Pieber, Frank Madeo
[link url="https://medicalxpress.com/news/2019-08-intermittent-fasting-fast-feast-diet.html"]Medical Xpress report[/link]
[link url="https://www.cell.com/cell-metabolism/fulltext/S1550-4131(19)30429-2"]Cell Metabolism abstract[/link]