Intermittent fasting has become a dietary trend whose benefits seem to be increasing exponentially. What is really happening, however, is that more and more research is being done on this diet method.

In fact, a review recently published in The New England Journal of Medicine has been able to analyze a number of studies on this subject, including both animal studies and human clinical trials, and taking into account the various types of fasting, and its potential benefits.

Intermittent fasting has been gaining importance over the last few years, experiencing its biggest boom over the past 3-4 years. However, scientists have been studying this dietary trend for decades, with the aim of glimpsing the effects of irregular caloric intake in animals, and now also on humans.

Metabolic Change

For Mark Mattson, lead author of the new work and neuroscientist at Johns Hopkins University, the key lies in a process called metabolic change.

This process would explain how an organism, lacking food, changes the way it produces energy, changing the use of glucose (easily accessible through food) to ketogenesis, where so-called ketones are created through the conversion of fat reserves, a process that also characterizes the ketogenic diet.

All this process where a change in energy production occurs is metabolic change, and exchanging metabolic states frequently would be what would lead to the health benefits of intermittent fasting, according to Mattson and his colleagues: “The periodic alternation between a normal metabolism and metabolic change not only provides the ketones needed to feed cells during fasting, but also causes highly orchestrated systemic and cellular responses that result in a mental and physical performance boost, as well as disease resistance”

As set out in the review, the benefits of intermittent fasting would cover up to five categories:

  • Cognitive improvements: Intermittent fasting would increase associative memory, spatial memory and working memory in animals, as well as verbal memory in adults.
  • Cardiovascular health improvements: Intermittent fasting would improve blood pressure and resting heart rate, thus reducing overall cardiovascular risk.
  • Improvements in physical activity: 16-hour intermittent fasting would have been shown to help reduce fat mass, maintaining the same muscle mass, in young men. Likewise, in lab mice, fasting on alternate days would increase their endurance in the race.
  • Improvements in diabetes and obesity: Intermittent fasting would help prevent obesity in animals, and would have been shown to be an effective method for weight loss in adult individuals.
  • Improvements in healing: Intermittent fasting would reduce tissue damage and recovery after surgery, at least in animals.

What kind of intermittent fasting is best

The review divided the types of fasting into two large groups: alternate-day fasting and time-restricted feeding. Fasting to alternate days would involve a significant caloric restriction on a day or more each week, while time restriction would involve fasting for a certain number of hours during a 24-hour cycle.

An example of alternate-day fasting is method 5:2, where caloric consumption is fasted or drastically restricted for 2 days a week, not contiguous with each other. For its part, with regard to time restriction, the most common is the 16:8 regimen, where it fasts for 16 hours and only food is consumed for a period of 8 hours each day.

To this day it is not clear what the ideal regimen of intermittent fasting is. At the moment it is known, as suggested by this new review, that ketones begin to rise in the first 8-12 hours of fasting, suggesting that time-restricted feeding methods could be effective on their own for profit for health, involving a real metabolic change, without specifying reaching the total 24 hours of fasting.

Therefore, according to the researchers, the 16:8 fasting regime would be an easy way to implement intermittent fasting. And, in fact, a recent study has gone so far as to suggest that a period of 14 hours of fasting a day already confers significant health benefits.