In an ongoing attempt to understand the etiology of obesity, I looked at the article that looked at a weight-loss diet that alternated periods of dieting [decreased energy balance] on a biweekly basis with periods of normalized energy balance.
- Byrne NM, Sainsbury A, King NA, Hills AP, Wood RE. Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. Int J Obes (Lond). February 2018;42(2):129-138. doi:10.1038/ijo.2017.206.
The MATADOR (Minimising Adaptive Thermogenesis And Deactivating Obesity Rebound) study examined whether intermittent energy restriction (ER) improved weight loss efficiency compared with continuous ER and, if so, whether intermittent ER attenuated compensatory responses associated with ER.
Greater weight and fat loss was achieved with intermittent ER. Interrupting ER with energy balance ‘rest periods’ may reduce compensatory metabolic responses and, in turn, improve weight loss efficiency.
The thought was this would be more sustainable and that the strategy would be more effective at weight loss compared to continuous dieting. It also hypothesized that this would counter the change in metabolism or basal energy. That is, the body decreases energy output in response to less food or in my opinion it increases the efficiency of mitochondria so that more energy is extracted from food.
Given that resting energy expenditure (REE) is determined largely by body size and composition, it is expected to decrease with weight loss. However, during ER, REE has been reported to decrease to a greater extent than that expected from changes in body composition, a phenomenon termed ‘adaptive thermogenesis’. This leads to markedly reduced efficiency of weight loss.
By alternating the diet, that counterbalance to metabolism wouldn’t occur, and that would make losing weight easier in the longer term.
This is exactly what they found. I believe this interesting finding also goes along with mitochondrial proton pump argument in that the 2-week fast was not sufficient to cause alterations in the genetic expression of mitochondria, so the constant shifting back and forth fasting and not fasting disable the ability of genetic change to alter metabolic efficiency.
There’s also a lengthy discussion of how this dietary approach with alternate weeks of fasting differs from intermittent fasting, which is quite accurate. They point out that the alternate week approach really has nothing to do with intermittent fasting because fasting on an every other day basis would be a completely different experience for the patients as well as for the body. This is a contrast to the bariatric weight-loss strategy, which is to starve the patient on a protein-sparing modified fast for 6 months, 9 months, or forever and to lose weight as fast as possible with the assumption that sooner or later the body will kick into a compensation. And then the only solution is to increase exercise (5-7 days per week).
In sum, they argue that the model we should engage folks in is periods of dieting alternating with periods of normal eating. This is an interesting concept, however, I am concerned that over time the unpleasantness of dieting will lose out to the pleasantness of eating. That is, the sense of hunger will overwhelm the sense of happiness with weight loss. As we know, there is very little reward from weight loss since the change is almost completely imperceptible both internally as well as externally. So, there is very little reward for weight loss. Alternatively, there is a huge punishment in terms of increased hunger for dieting. So, I believe the potential utility of this behavioral model is limited not by its potential usefulness, but by its applicability and low adherence.