Metabolic damage: a scientific review

Metabolic damage. It’s every dieter’s worst nightmare. The theory of metabolic damage states that your metabolism slows down permanently, i.e. is damaged, after prolonged periods of being in energy deficit. This decrease in energy expenditure has been used to explain the occurrence of the yo-yo effect whereby people that have dieted for a long time often quickly regain their lost fat when they stop dieting.

 

But so far no scientific publication has actually scrutinized the theory of metabolic damage, so the Bayesian research team sought to investigate whether metabolic damage actually occurred. Our findings have now been published in the Medical Research Archives.

 

Read the full paper in the Medical Research Archives (open access).

 

For a less technical and more lay friendly explanation, see Menno’s opening statement in the reverse dieting debate with Layne Norton, Eric Helms and Peter Fitschen.

 

Short summary

Human metabolism is strongly affected by an individual’s body composition, with lean body mass, in particular organ mass, having a strong positive relation with energy expenditure and fat mass having little direct effect on energy expenditure. However, fat mass stores do relate with adaptive thermogenesis, the phenomenon that your metabolism, particularly your non-exercise physical activity level, decreases along with body fat stores.

Secondly, human metabolism is significantly affected by energy intake with higher energy intakes resulting in higher energy expenditure.

When you take body composition and energy intake into account, there is no evidence of metabolic damage in the literature. This includes anorectic women, malnourished individuals, research for the Second World War on the effects of starvation, bodybuilders during contest prep and wrestlers that aggressively make weight for their competitions. Human metabolism adapts, but even in extreme cases it does not suffer permanent damage. As such, metabolic damage can be considered a myth.

 

6 Comments

  1. Jason says:

    Dr. Rudy Leibel has been working in this field since late 80’s and (at least as late as 2012) has come to conclusions of altered set point once individuals have gained weight, then reduced to lower weight. source: https://www.youtube.com/watch?v=2i_cmltmQ6A&t=5m27s

    Menno, what are your thoughts on this roughly 2.5 min clip?

    • Jason says:

      i.e The thing I’m most curious about is NOT if a 200lbs male who diets down to 150lbs, and then regains the weight back has reduced metabolism now back at the same 200lbs weight (assuming body composition has not changed). It think this has been well documented that it does not. Your paper illustrates this. But rather I’m curious about the REVERSE. That is, if a 150lb male gains weight to 200lbs and later diets back down to 150lbs is his metabolism the same in terms of RMR (when correcting for age, body composition, etc) as it was when he was initially at 150lbs.

      And maybe the bigger question is: does it matter — are these two scenarios the same or different?

      It think they are different because the question proposed is can “set point” become raised by weight loss OR weight gain?

    • The whole concept of a set-point is a myth. There’s only a natural equilibrium effect. The truth in this message is that most people that go on a weight loss diet lose fat and lean body mass and therefore end up with a lower metabolic rate than before the diet.

      • Connor says:

        1. As far as lean mass is concerned, how pronounced can the loss be compared to fat? I know many people that prefer a steep deficit on their cuts; curious to know whether loss of strength is mostly due to nutrition/being flat at the time, muscle loss or some combination of the two.

        2. Is there a link to the full literature on metabolic damage? I’m only getting the abstract, no access to the full piece. Would love to read the expanded version.

        • 1. There’s no limit in principle, but if you’re losing more than 25% LBM in practically any scenario, something’s wrong.
          2. The article is open access: you can read the full text on the journal website.

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