Fasting for weight loss: an effective strategy or latest dieting trend?

Abstract

With the increasing obesity epidemic comes the search for effective dietary approaches for calorie restriction and weight loss. Here I examine whether fasting is the latest 'fad diet' as portrayed in popular media and discuss whether it is a safe and effective approach or whether it is an idiosyncratic diet trend that promotes short-term weight loss, with no concern for long-term weight maintenance. Fasting has long been used under historical and experimental conditions and has recently been popularised by 'intermittent fasting' or 'modified fasting' regimes, in which a very low-calorie allowance is allowed, on alternate days (ADF) or 2 days a week (5:2 diet), where 'normal' eating is resumed on non-diet days. It is a simple concept, which makes it easy to follow with no difficult calorie counting every other day. This approach does seem to promote weight loss, but is linked to hunger, which can be a limiting factor for maintaining food restriction. The potential health benefits of fasting can be related to both the acute food restriction and chronic influence of weight loss; the long-term effect of chronic food restriction in humans is not yet clear, but may be a potentially interesting future dietary strategy for longevity, particularly given the overweight epidemic. One approach does not fit all in the quest to achieve body weight control, but this could be a dietary strategy for consideration. With the obesity epidemic comes the search for dietary strategies to (i) prevent weight gain, (ii) promote weight loss and (iii) prevent weight regain. With over half of the population of the United Kingdom and other developed countries being collectively overweight or obese, there is considerable pressure to achieve these goals, from both a public health and a clinical perspective. Certainly not one dietary approach will solve these complex problems. Although there is some long-term success with gastric surgical options for morbid obesity, there is still a requirement for dietary approaches for weight management for the overweight and obese population, particularly as invasive interventions carry post-operative risk of death due to complications. Effective dietary interventions are required that promote long-term adherence and sustained beneficial effects on metabolic and disease markers. In general, such interventions need to be palatable and satiating, meet minimal nutritional requirements, promote loss of fat and preserve lean body mass, ensure long-term safety, be simple to administer and monitor and have widespread public health utility. Intermittent fasting or alternate day fasting may be an option for achieving weight loss and maintenance.

Plasticity of adipose tissue in response to fasting and refeeding in male mice

“…There are different forms of fasting, including intermittent fasting and periodic fasting lasting several days or longer (two or more weeks) [9]. Rather than reducing daily total caloric intake, intermittent fasting (IMF) has received attention as a possible approach for long-term weight loss [10, 13]. However, there are some controversies regarding the effects of fasting and refeeding on weight regain [14, 15].…”

Effect of 48 h Fasting on Autonomic Function, Brain Activity, Cognition, and Mood in Amateur Weight Lifters

“…Fasting is also widely used and recommended for rapid weight loss [1–3] and for disease prevention and treatment [2]. It is well known that long-term intermittent and periodic fasting promotes health and reduces the risk of many chronic diseases, such as cancer, neurodegenerative diseases, metabolic syndrome, hypertension, and inflammation [2].…”

Feast and famine: Adipose tissue adaptations for healthy aging

“…Increased health span and longevity in rodents has been linked since many years to intermittent fasting that is a protracted time without ingestion of calories and nutrients for at least 20 hours on alternate days (Carlson and Hoelzel, 1946;Martin et al, 2006;Mattson and Wan, 2005). Studies carried out in humans demonstrated that several weeks of an alternate day fasting (ADF) reduce body weight and fat mass and improve clinical health markers thus restraining metabolic dysfunctions likely leading to prolonged life span (Johnstone, 2015;Seimon et al, 2015;Tinsley and La Bounty, 2015). However, only a few human studies have 4 tested the effects of ADF on body weight and pro-longevity parameters in non-obese subjects.…”