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Unveiling the impact of fasting diets on eating behaviors, sleep, and mood

Food crisis

HQ Team

January 29, 2024: Fasting diets (FDs) have gained popularity for their impact on health, disease, and weight control. Despite the vast research on FDs, there are still large lacunas in their effects on eating behaviors, sleep, and mental health.

In a latest comprehensive review, researchers have dealt with how FDs affect eating behaviors, mood, sleep, and overall well-being and the beneficial effects of FDs on the gut microbiome.

Historical roots and modern applications

Since ancient times fasting has been used to treat seizures and it slowly evolved as a possible solution for various health conditions. Modern studies highlight its effects on serum glucose reduction, glycogen depletion, and a shift to ketogenesis. Fasting’s impact on anxiety behavior and cognition is another aspect that adds to its attraction for many.

Evidence suggests benefits in weight control, metabolic health, and anti-aging effects, with potential relief for disorders like Alzheimer’s, Parkinson’s, multiple sclerosis, epilepsy, and stroke.

Variability in fasting protocols

The review has looked into the various protocols, including alternate-day fasting(ADF), 5:2 intermittent fasting, periodic fasting, time-restricted feeding, and religious fasting regimes. This allows a nuanced exploration of the effects of different fasting approaches on mental health components.

In calorie-restrictive (CR) diets, subjects tend to regain the lost weight once they get off the restrictions. Some studies suggest that following an FD can lead to lower feelings of hunger, compensatory eating, and weight regain than CRs, while others find that the two strategies are equivalent.

Some papers found that CR is associated with flexible restraint, leading to lower adiposity and binge eating, while FDs often follow a more rigid ‘all or nothing’ approach, which can cause overeating. Others have found no difference in emotional eating between ADF regimens and regular diets.

Modifications in sleep-wake patterns

Studies exhibit varied outcomes regarding CDs impact on insomnia severity or sleep duration. Some research shows no significant effects, while others highlight improvements in sleep quality. Notably, fasting during Ramadan has been associated with increased daytime sleepiness, hinting at the potential of FDs to address disturbances in circadian rhythms caused by health conditions or shift work.

Effects on mood and emotional well-being

FDs emerge as influential contributors to mood enhancement, with significant reductions in anger, confusion, tension, depression, and overall mood disturbance, coupled with heightened energy levels. However, these mood improvements are primarily noted in the short term, prompting the need for future studies.

The impact of FDs on mood may find its roots in the intricate network of the gut-brain axis. Individuals with depression and anxiety commonly experience gastrointestinal complaints, emphasizing the interconnected nature of gut health and mental well-being. Intermittent fasting, a component of FDs, has demonstrated positive effects on gut health, leading to increased production of active metabolites and neurotransmitters.

Additionally, the heightened production of ketone bodies represents another potential mechanism influencing mood positively. The literature underscores the effectiveness of FDs when coupled with sufficient sleep and synchronized mealtimes with the body’s circadian rhythms.


The reviewers say that the broad range of findings may stem from the lack of consistency among various studies. Differences in sample size, study populations, intervention duration, and study design contribute to the heterogeneity in results. Notably, it seems that younger subjects are more prone to overeating during fasting diets (FDs) in comparison to their middle-aged counterparts.

A notable limitation in several studies is the absence of control groups, and surprisingly, none of them delved into the impact of FDs on satiation. To establish a more robust understanding of the effectiveness of FDs in enhancing eating behaviors, both in the short and long term, a more systematic approach is imperative. Future studies should employ comparable study designs and analyses, addressing these gaps and ensuring a more comprehensive evaluation of the efficacy of FDs.

Further research is required to provide evidence-based insights, offering guidance on the optimal integration of FDs into health strategies for various conditions.

The review is available in Frontiers in Nutrition,

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