|This & other studies show no increased binge eating risk on non-fasting days.|
In view of the far-reaching effects of our biological clock and its close interaction with food intake and nutrient availability, it is, after all, only logical to assume that food timing could have a significant effect on our metabolic health.
Previous research suggests that at least some of the benefits of intermittent or alternate day fasting are mediated by the interaction of the fasting / feeding cycle with our circadian rhythm. If that's indeed the case (and the evidence is quite convincing), it is not illusionary to assume that the timing of the meal(s) / feeding window on (intermittent) fasting days could affect the proven beneficial effects of these diet regimen, as well... I guess this or something like this was also what Kristin Hoddy told her thesis adviser, Krista A. Varady, before she started her research into the effects of "Meal Timing during Alternate Day Fasting". Research, the results of which have just been published by the University of Illinois at Chicago (Hoddy. 2016).
The trial itself consisted of a two-week lead-in followed by 8 weeks of alternate day fasting (ADF) - a basic template that identical for all subjects (BMI between 30 and 39.9 kg/m²; age between 25 and 65 years), the time at which the subjects were told to consume their only meal on the fasting day, however, differed for the three study groups the N = 74 subjects were randomly (stratified based on sex, age, and BMI) assigned to:
- in the ADF-L group, the subjects consumed their only meal at launch
- in the ADF-D group, the subjects consumed their only meal at dinner, and
- in the ADF-SM group, the ~500kcal were split into small meals throughout the day
|Table 1: The meals for the fast days were prepared for the subjects; here's the nutrient composition (Hoddy. 2016).|
|Figure 1: Changes in body weight and body composition during the weight loss period (Hoddy. 2016).|
read the article), but the respective study is not the only paper that discusses the efficacy of alternate day fasting and regular calorie restrictions. A recent systematic review and meta-analysis by Alhamdan et al. concludes (in line with what I've written in the previously referenced article] "that ADF is an efficacious dietary method, and may be superior to VLCD [very low-calorie diet] for some patients because of ease of compliance, greater fat mass loss and relative preservation of fat-free mass" (Alhamdan. 2016).With visceral fat being one of the drivers of inflammation and the metabolic syndrome, it would thus seem as if eating only one meal and eating this meal between 12 pm and 2 pm was a bad idea if your goal was to improve your metabolic health. Other parameters Hoddy analyzed do yet not support this notion. In fact, not a single of the metabolic disease factors she tracked during the 10-week study showed significant inter-group differences.
|Figure 2: Changes in metabolic disease factors over the course of the study (Hoddy. 2016).|
"Improvements in LDL particle size occurred in all of the groups. This was marked by an increase in the proportion of large LDL particles in all intervention groups, and a decrease in the proportion of small LDL particles in only the ADF-D and ADF-SM groups. This shift in LDL particle size represents a reduction of atherosclerotic risk."(Hoddy. 2016)Overall, it does therefore probably not matter when you consume your ADF 'fast day meal', what will matter, however, is that you are able to stick to the rules, i.e. to not consume any other foods and based on my own intermittent fasting experience, that's going to be increasingly hard with both, the ADF-L and the ADF-SM regimen - corresponding data is unfortunately not available, because Hoddy et al. analyzed parameters such as the change in appetite hormones after weight loss only based on pooled ADF data.
- Alhamdan, B. A., et al. "Alternate‐day versus daily energy restriction diets: which is more effective for weight loss? A systematic review and meta‐analysis." Obesity Science & Practice 2.3 (2016): 293-302.
- Catenacci, Victoria A., et al. "A randomized pilot study comparing zero‐calorie alternate‐day fasting to daily caloric restriction in adults with obesity." Obesity 24.9 (2016): 1874-1883.
- Hoddy, Kristin. Meal Timing during Alternate Day Fasting: Effect on Body Weight and Cardiovascular Disease Risk. Diss. University of Illinois at Chicago, 2016.
- Klempel, Monica C., Cynthia M. Kroeger, and Krista A. Varady. "Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cardio-protection as ADF with a low-fat diet." Metabolism 62.1 (2013): 137-143.
- Varady, Kristina A. "Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss?." obesity reviews 12.7 (2011): e593-e601.