Role of Adaptive Thermogenesis in Unsuccessful Weight-Loss Intervention

Angelo Tremblay; Geneviève Major; Éric Doucet; Paul Trayhurn; Arne Astrup

Disclosures

Future Lipidology. 2007;2(6):651-658. 

In This Article

Adaptive Thermogenesis as a Protective Mechanism Against Environmental Hazards

The research conducted in Laval University during the past 10 years on body organochlorines (OCs) and obesity probably offers the best example to discuss the issue of a protective role for adaptive thermogenesis. As previously described, the interest for OCs in the study of obesity is related to their lipid soluble properties.[68] Despite the fact that the use of these compounds has now been banned in many countries for several decades, they persist in the body of every person on the planet because of their long half-life and their transport via air from countries where they still remain in use.[69,70,71] As summarized in Table 3 , their effects on thyroid function and mitochondrial functionality theoretically confer to these compounds an antithermogenic profile.

At the end of the 1970s, Backman and Kolmodin-Hedman were the first investigators to report a significant increase in circulating OCs with body weight loss.[78] This hyperconcentration in plasma OCs depends on body weight loss, specifically, the importance of the decrease in their dilution space. In this regard, it was recently demonstrated that the increase in the plasma concentration of OCs corresponded to 388% of baseline values in obese patients tested 1 year after bariatric surgery.[79]

The integration of these observations also led some of us to examine the potential impact of OCs as an explanatory factor for the decrease in thermogenesis favored by weight loss in humans. Since this issue also cannot be directly tested for ethical reasons, a stepwise multiple regression analysis was used to quantify the contribution of various factors, including OCs, on the variance of changes in sleeping metabolic rate induced by body weight loss. The main finding of this study was that changes in plasma OC concentration explained half of the variance in the greater than predicted decrease in sleeping metabolic rate measured by whole-body indirect calorimetry.[80]

This finding is ecologically important since it provides an indication of the potential detrimental role of chemical pollution on the control of human energy expenditure. Since the documentation of this effect is the outcome of an association study rather than of a direct experimental demonstration, it is clear that it will not be possible to get a definitive proof of this concept. However, biological common sense would suggest that the accentuation of the thermogenic decrease occuring with weight loss appears to be useful to attenuate the decrease in the dilution space of OCs and to prevent more pronounced perturbations of body homeostasis.

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