Fasting has been practiced for centuries for religious, cultural, and health reasons. The recent surge in popularity of fasting as a weight loss and health-promoting tool has brought it to the forefront of public attention. Fasting is often associated with weight loss, improved insulin sensitivity, and reduced inflammation. While there is evidence to support some of these claims, it is essential to understand the science behind fasting to separate fact from fiction.
Fasting is an umbrella term for various types of dietary patterns that involve calorie restriction for a certain period. The most common forms of fasting are alternate-day fasting, time-restricted feeding, and periodic prolonged fasting. Alternate-day fasting involves alternating between days of normal food intake and days of complete or partial calorie restriction. Time-restricted feeding restricts the eating window to a certain number of hours per day. Periodic prolonged fasting involves fasting for two or more days at a time, several times a year.
One of the most significant reasons people turn to fasting is for weight loss. While fasting can help people lose weight, it is not a superior strategy for fat loss. A meta-analysis of 40 randomized controlled trials found that while intermittent fasting was associated with modest weight loss, it was no more effective than other calorie-restricted diets for weight loss (Harris et al., 2018). In other words, fasting may be an effective tool for weight loss, but it is not the best or only strategy for fat loss.
Fasting has been proposed to have other benefits beyond weight loss, including improved insulin sensitivity and reduced inflammation. A systematic review of 28 randomized controlled trials found that intermittent fasting was associated with significant reductions in insulin resistance, blood pressure, and inflammation (Ganesan et al., 2018). However, the study authors noted that the quality of evidence was low to moderate, and more high-quality research is needed.
Another proposed benefit of fasting is the activation of autophagy, the process by which cells remove and recycle damaged parts. While animal studies have shown that fasting can promote autophagy, there is limited evidence to support this claim in humans (Longo & Panda, 2016). More research is needed to determine whether fasting can activate autophagy in humans and what implications it may have for health.
In conclusion, fasting can be a useful tool for weight loss and has other potential health benefits. However, it is not a superior or exclusive strategy for fat loss, and more research is needed to understand its full effects on health. Before embarking on a fasting regimen, it is essential to consult with a professional to ensure it is safe and appropriate.
References:
Ganesan, K., Habboush, Y., & Sultan, S. (2018). Intermittent fasting: The choice for a healthier lifestyle. Cureus, 10(7), e2947. doi: 10.7759/cureus.2947
Harris, L., Hamilton, S., Azevedo, L. B., Olajide, J., De Brún, C., Waller, G., . . . Ells, L. (2018). Intermittent fasting interventions for treatment of overweight and obesity in adults: A systematic review and meta-analysis. JBI
Database of Systematic Reviews and Implementation Reports, 16(2), 507-547. doi: 10.11124/JBISRIR-2016-003248
Longo, V. D., & Panda, S. (2016). Fasting, circadian rhythms, and time-restricted feeding in healthy lifespan. Cell Metabolism, 23(6), 1048-1059. doi: 10.1016/j.cmet.
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