Tuesday, February 7, 2017

Collateral Fattening

By: Andrew Jagim

First of all, can we all take a moment to appreciate the clever title of the article (which was used in the original scientific article might I add)?  So what is this term referring to and why should you care? Collateral fattening is a term coined by Dr. Dulloo in a recent review article. In the article, Dr. Dulloo discuss the dynamic relationship between different components of body composition and how they may drive energy intake aka the amount of calories we eat on any given day.  The author discusses specifically how there appears to be a relationship between fat-free mass and one's body fat percentage and collectively this also appears to influence energy intake.  Such that, if someone is increasing fat-free mass it may serve as a signal to increase energy intake to facilitate the increases in lean mass and support the increased metabolically active tissue as evidenced by observed increases in resting metabolic rate following increases in lean mass. 

However, interestingly enough this drive to increase energy intake also appears to occur when there is a reduction in fat-free mass.  This appears to be a result of a feedback signaling pathway which is our body's way of trying to increase energy intake in an attempt to restore the lost fat-free mass. 

The problem is, when we do this, we are more likely to store those additional calories as fat mass rather than fat-free mass thus leading to "Collateral Fattening." Part of the reason is because our daily expenditure is reduced as a result of the lost fat-free mass making us more likely to be in a state of positive energy balance as depicted in the figure to the right.  

So when individuals lose weight, particularly fat-free mass, they are more susceptible to experience subsequent increases in fat mass as they will feel more hungry, leading to an increase in energy intake, and their resting metabolic rate has been lowered. To make matters worse, often times people will gain more body fat than they even started with and "over shoot" their previous body fat levels as their body is still trying to restore fat-free mass.  

Individuals who continually get caught up in weight cycling and intermittent dieting likely are experiencing these feedback loops with subsequent fluctuations in body composition, for the worse unfortunately; something that will just get worse over time unless more focused diet and exercise efforts are implemented.

So how does one prevent collateral fattening? 
If you are someone who is looking to lose weight, try to minimize the amount of lean mass you lose in the process? How, by performing strength training throughout your diet and making sure to eat adequate amounts of protein to preserve lean mass while in a caloric deficit. This will help to minimize reductions in lean mass and minimize reductions in your resting metabolism which ultimately should help to curb hunger cravings and prevent collateral fattening from occurring.

Dulloo, A. G. (2017), Collateral fattening: When a deficit in lean body mass drives overeating. Obesity, 25: 277–279. doi:10.1002/oby.21734

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