Obesity Does Not Protect From Loss of Lean Tissue During Weight LossThursday, February 11, 2010
One of the biggest challenges during weight loss is the maintenance of lean body mass. In this regard, I have previously blogged about the importance of maintaining adequate protein intake even when restricting overall caloric intake. (Another important measure in this regard is resistance training).
A common misconception appears to be that obese people have enough stored energy to live off so that one can confidently reduce their caloric intake to help them lose weight – the fewer calories the better.
Nothing else can be further from the truth – as it turns out, obese individuals are just as, if not more, prone to losing lean tissue (mainly skeletal muscle) as are lean individuals.
This is nicely demonstrated in a study by Gregory Henderson and colleagues from the Mayo Clinic, just published in the journal Obesity.
In this study, whole body protein metabolism was studied in twelve obese women over a wide range of BMIs using leucine-tracer techniques following five days of a weight-maintaining diet and then after 30 days of a 1,400 kcal deficit with maintained protein intake.
Before weight loss, when expressed as total rates, per body weight (BW) or per fat-free mass (FFM), leucine rate of appearance (Ra), and nonoxidative leucine disposal (NOLD) were significantly higher in the heavier individuals indicating higher protein turnover.
Nevertheless, caloric restriction reduced protein turnover and oxidation to the same extent in obese and non-obese individuals showing that higher fat mass does not favorably alter the response of protein metabolism and clearly does not mitigate the loss of lean body mass with caloric restriction.
As any loss of lean body mass, a key determinant of resting metabolic rate, would be counterproductive both by limiting weight loss and by facilitating weight regain, it is indeed essential to maintain or perhaps even increase protein intake when reducing overall caloric intake.
The notion that obese people have enough stored calories and can therefore easily go without adequate protein intake (or perhaps no food at all) for a few days is plain wrong.
Happy to hear of any experiences with excessive lean body mass during weight reduction and prescribed measures to limit this loss.