Effectiveness of Intermittent Fasting and Time-Restricted Feeding Compared to Continuous Energy Restriction for Weight Loss

Abstract

The current obesity epidemic is staggering in terms of its magnitude and public health impact. Current guidelines recommend continuous energy restriction (CER) along with a comprehensive lifestyle intervention as the cornerstone of obesity treatment, yet this approach produces modest weight loss on average. Recently, there has been increased interest in identifying alternative dietary weight loss strategies that involve restricting energy intake to certain periods of the day or prolonging the fasting interval between meals (i.e., intermittent energy restriction, IER). These strategies include intermittent fasting (IMF; >60% energy restriction on 2–3 days per week, or on alternate days) and time-restricted feeding (TRF; limiting the daily period of food intake to 8–10 h or less on most days of the week). Here, we summarize the current evidence for IER regimens as treatments for overweight and obesity. Specifically, we review randomized trials of ≥8 weeks in duration performed in adults with overweight or obesity (BMI ≥ 25 kg/m2) in which an IER paradigm (IMF or TRF) was compared to CER, with the primary outcome being weight loss. Overall, the available evidence suggests that IER paradigms produce equivalent weight loss when compared to CER, with 9 out of 11 studies reviewed showing no differences between groups in weight or body fat loss.

Evidence-based clinical advice for nutrition and dietary weight loss strategies for the management of NAFLD and NASH

“…Evidence suggests that intermittent energy restriction results in equivalent weight loss compared to continuous energy restriction in the short-term, with a lack of long-term data. 27 Several RCTs have looked at the effectiveness of IF in the setting of NAFLD. An 8 weeks modified alternate-day calorie restriction was found to lead to reductions in BMI, liver enzymes, liver steatosis and liver stiffness (based on shear wave elastography) compared to no intervention with adherence rates of 75-83%.…”

Intermittent Fasting, Nutritional Supplementation, and Resistance Training as Strategy for Body Weight Loss: An Update

“…However, there has been increased interest in identifying alternative dietary weight loss strategies that involve restricting energy intake to certain periods of the day or prolonging the fasting interval between meals (i.e., intermittent energy restriction, IER). These strategies include intermittent fasting (IF; >60 % energy restriction on 2-3 days per week, or on alternate days) and time-restricted feeding (TRF; limiting the daily period of food intake to 8-10 h or less on most days of the week) (Rynders et al, 2019). IF covers a broad class of interventions that alternate periods of eating and extended fasting, where it is associated with substantial weight loss in short periods of time, during around 8 to 12 weeks.…”

Is Caloric Restriction Associated with Better Healthy Aging Outcomes? A Systematic Review and Meta-Analysis of Randomized Controlled Trials

“…In fact, different SRs have explored the association between CR and asthma [19], hypercholesterolemia [20], cardiovascular health [4] or bone health [21]. On the other hand, some SRs have examined the general effects of diet [22] or intermittent energy restriction [23] on health, while others took in consideration specific populations such as intensive care units patients [24], athletes [25] or animal models [26]. Finally, Miller and colleagues [27] analyzed the effect of CR in combination with physical exercise, whereas studies published by Seyfried et al [28], Omodei et al [29] and Locher et al [30] did not represent systematic reviews of current evidence on CR.…”