Dietary and physical activity adaptations to alternate day modified fasting: implications for optimal weight loss

Abstract

BackgroundAlternate day modified fasting (ADMF) is an effective strategy for weight loss in obese adults.ObjectiveThe objective of this study was to examine the dietary and physical activity adaptations that occur during short-term ADMF, and to determine how these modulations affect rate of weight loss.MethodsSixteen obese subjects (12 women/4 men) completed a 10-week trial consisting of 3 phases: 1) 2-week control phase, 2) 4-week ADMF controlled feeding phase, and 3) 4-week ADMF self-selected feeding phase.ResultsBody weight decreased (P < 0.001) by 5.6 ± 1.0 kg post-treatment. Energy intake on the fast day was 26 ± 3% of baseline needs (501 ± 28 kcal/d). No hyperphagic response occurred on the feed day (95 ± 6% of baseline needs consumed, 1801 ± 226 kcal/d). Daily energy restriction (37 ± 7%) was correlated to rate of weight loss (r = 0.42, P = 0.01). Dietary fat intake decreased (36% to 33% of kcal, P < 0.05) with dietary counseling, and was related to rate of weight loss (r = 0.38, P = 0.03). Hunger on the fast day decreased (P < 0.05) by week 2, and remained low. Habitual physical activity was maintained throughout the study (fast day: 6416 ± 851 steps/d; feed day: 6569 ± 910 steps/d).ConclusionThese findings indicate that obese subjects quickly adapt to ADMF, and that changes in energy/macronutrient intake, hunger, and maintenance of physical activity play a role in influencing rate of weight loss by ADMF.

Health effects of intermittent fasting: hormesis or harm? A systematic review

“…Whereas enthusiasm for fasting is increasing, clinical relevance remains low because of insufficient human data, including almost nonexistent controlled trials (21,(33)(34)(35)(36), few clinical outcomes studies (37,38), lack of correction for inflated type I error rates from multiple hypothesis tests, and limited safety data (39)(40)(41). The evidence suggests, however, that therapeutic fasting may provide substantial benefit for reducing clinical risk.…”

“…This study did not evaluate subject safety outcomes. Safety data for ADF regimens are lacking, but ADF has been shown to not cause an increase in caloric intake on nonfasting days, despite what some may expect from the effects of prolonged hunger (39,40). Some of the weight-loss studies, including the one trial just mentioned and some noted in the introduction, evaluated metabolic, cardiovascular, and cognitive benefits as secondary outcomes.…”

The Effects of Intermittent Energy Restriction on Indices of Cardiometabolic Health

“…84 When interpreting these findings, it should be noted that assessment of appetite is highly variable between individuals. 85 Additionally, overweight/obese subjects entering weight-loss trials are self-referring and so typically exhibit greater levels of motivation and cognitive eating-restraint.…”

Potential Benefits and Harms of Intermittent Energy Restriction and Intermittent Fasting Amongst Obese, Overweight and Normal Weight Subjects—A Narrative Review of Human and Animal Evidence

“…Energy intake was not presented in the RCT of ADER compared to CER [14], however previous reports of ADER have similarly found a small carry over effect with a 5% reduction in energy on the non-restricted days of the regimen [38]. A number of studies were testing combined IER/CER and exercise interventions [13,26,33] and reported exercise to be feasible alongside both IER and CER diets, but there are no reported interactions between diet allocation and levels of activity and weight loss.…”