|This is exactly the way your plate will look during true alternate day fasting.|
That's until now, though! Scientists from the University of Colorado Anschutz Medical Campus randomized decently healthy, but obese adults BMI 30 kg/m², age 18-55) to either (a) a zero-calorie ADF (n = 14) or chronically energy reduced (CR | -400 kcal/day, n = 12) diet for 8 weeks. Outcomes were measured at the end of the 8-week intervention and after 24 weeks of unsupervised follow-up.
What is important to understand is that the study diets were not designed to produce comparable energy deficits. Now, at first sight, this may sound stupid, but eventually, this and the 24-week unsupervised follow-up make the study more practically relevant with respect to the actually relevant research question: Is ADF better than a standard-of-care weight loss diet (moderate daily CR)? The existing difference between the two diets which had identical macronutrient profiles (55% carbohydrate, 15% protein, and 30% fat) is described as follows:
- CR participants were provided a diet that produced a -28% (that was more than intended) deficit from estimated energy requirements (considered a standard-of-care weight loss diet at the time the study was designed).
- ADF participants were provided a diet but instructed to fast on alternate days. On fed days, they were provided a diet estimated to meet estimated energy requirements, which was supplemented with ad libitum (as much as they wanted) access to five to seven optional food modules (200 kcal each). ADF participants were permitted to eat as much as they wished on fed days, but were not encouraged to eat all food provided. On fast days, ADF participants were instructed to begin their fast after the evening meal the preceding day, and to consume only water, calorie-free beverages, and bouillon/stock cube soup.
using PROnutra software (Viocare Technologies Inc., Princeton NJ). Estimated energy deficits were calculated by subtracting estimated daily EI from estimated daily energy requirements.
|Table 1: Mean daily energy and macronutrient intake on fast and fed days over 8 weeks in ADF (Catenacci. 2016); corresponding data for weeks 9-32 not available.|
|Figure 1: Changes in body composition (%) during the initial tightly controlled 8 weeks and at the end of the subsequent "real-world" uncontrolled 24 weeks, i.e. at the end of the 32 weeks (Catenacci. 2016).|
|Figure 1: Absolute (see below for explanation) advantage in changes of body composition in the ADF group (left) and changes in resting metabolic rate (in kcal/d) in the controlled early and uncontrolled follow-up (Catenaccio. 2016).|
Against that background, it is also not surprising that the study at hand suggests that ADF dieting is also less likely to cause / promote the dreaded yo-yo effect: With the total fat mass (%) declining and the lean mass (%) inclining only in the ADF, yet not in the CR group where the body composition kept deteriorating in the 24 weeks of unsupervised follow-up, I previously called "the real-world phase".
- An, Juan Ji, et al. "Discrete BDNF neurons in the paraventricular hypothalamus control feeding and energy expenditure." Cell metabolism 22.1 (2015): 175-188.
- Bariohay, Bruno, et al. "Brain-derived neurotrophic factor plays a role as an anorexigenic factor in the dorsal vagal complex." Endocrinology 146.12 (2005): 5612-5620.
- 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.
- Xu, Baoji, et al. "Brain-derived neurotrophic factor regulates energy balance downstream of melanocortin-4 receptor." Nature neuroscience 6.7 (2003): 736-742.