Unlocking the secrets of fasting diets: From ancient practices to modern health solutions

09 Jan 2024 --- An international team of researchers are unveiling the results of a comprehensive review of the impacts of fasting diets (FDs) on eating behaviors, sleep quality and overall mood.

The team — hailing from Canada, Germany, Iran, Italy and Tunisia — notes that fasting as a health practice dates back to ancient times. Still, its recent popularity stems from its effects on reducing serum glucose and promoting a shift from glycolysis to ketogenesis.

As the diet is currently garnering attention for its physical and potential mental health benefits, the researchers state that their goal is to critically examine the research surrounding FDs and address gaps in the diet’s role in diet satisfaction, satiety and mental health.

Recent findings
The researchers state that FDs are often associated with better adherence compared to calorie-restricted regimens and have been shown to influence eating behaviors crucial for physical and mental well-being significantly.

Recently, intermittent FDs have been associated with several health benefits, including a recent study that found that limiting the time period for eating affects 22 areas of the body and brain, potentially offering benefits for conditions like cancer, heart disease, and hypertension.

Moreover, researchers in the US found that limiting eating times could help with the daily Circadian rhythm and sleep disturbances linked to Alzheimer’s disease, leading to better memory, sleep and thinking skills.

Additionally, a study from China suggests that intermittent fasting could potentially reverse type 2 diabetes. Other research shows it is one of the best diet for metabolic disorders alongside the Mediterranean, low-calorie, low-carbohydrate, low-glycemic-index and plant-based diets.

Types of fasting
The review, published in Frontiers in Nutrition, included more than 35 studies. This encompasses thousands of participants from many different different groups.

The researchers classify various fasting diets, including alternate day fasting (ADF), 5:2 intermittent fasting (IF), periodic fasting, time-restricted feeding (TRF) and religious fasting regimes, each with distinct characteristics and health impacts.

According to the team, ADF involves eating very little every other day while eating normally on alternate days. The 5:2 IF means that a person fasts for two non-consecutive days and eats regularly for the other five days of the week.

Furthermore, periodic fasting involves limiting food one or two days a week and TRF means that a person does not eat for eight to 12 hours daily. Religious fasts, like Ramadan, involve fasting from dawn to sunset for a month.

Findings on fasting’s effects
According to the researchers, while short-term fasting interventions may decrease hunger, the long-term beneficial effects of FDs remain unclear. They caution against extrapolating short-term findings to longer periods and call for more research on the long-term effects of fasting diets on eating behaviors.

Moreover, the team explains that it also looked at the psychological impacts of fasting diets, differentiating between hunger-driven eating and eating for pleasure. The review states that when looking at dietary restraint and disinhibition — both important factors in obesity, dieting and eating disorders — it found variable effects on these eating behavior traits.

They further state that the impact of fasting diets on mood and their use as treatments are not well understood as it is unclear which type of fasting is most beneficial for groups or individuals and studies comparing their effects are inconsistent. Also, the limited research and varying study designs make it hard to evaluate different fasting methods effectively.

However, the researchers conclude that fasting diets have shown significant short-term benefits compared to calorie-restricted diets and may offer a new way to address conditions related to eating behaviors and disease complications, as changing eating habits can significantly affect health.

Though the review states that further study on how different fasting methods affect diseases is needed, it also acknowledges that current research indicates that combining fasting diets with proper sleep and eating in tune with the body’s natural clock can enhance metabolism.

Edited by William Bradford Nichols