Thursday, May 19, 2011

Optimal Weight Loss for Athletes: Lose No More Than 0.7% of Your Body Mass Per Week if You Want to Retain or Even Build Lean Mass While Dieting

Image 1: Slow dieting paves the way to
an aesthetic and strong body
A question intricately related to my dissertations in episode #698 of Carl Lenore's Super Human Radio, was and still is the question of the optimal rate, i.e. weight/time, of weight loss to a) maintain a healthy metabolism and b) keep as much muscle mass as possible. While this issue certainly is relevant for the average person, it is of essential importance to an athlete competing in a sport with weight classes. Even if at "weighing day" he or she has the desired body weight, "making" this weight would have been worthless, if he or she had lost too much previous muscle to maintain adequate performance... It is thus surprising that the amount of studies that look into the effects of fast vs. slow weight loss on body composition in an athletic population is rather small, which renders the results of a recent Norwegian study (Garthe. 2011) interesting, all the more.

Garthe et al. put a group of 24 trained athletes onto a slow (SL: 0.7% body weight per week) or fast (FR: 1.4% body weight per week) weight loss regimen hypothesizing that "the faster WL regimen would result in more detrimental effects on both LBM and strength-related performance".

Figure 1: Changes in body composition for different amounts of weight loss per week;
FR 1.4% body weight loss/wk, SR 0.7% body weight loss/wk (data adapted from Garthe. 2011)

Over the course of 8 weeks, the athletes maintained their usual 4x a week resistance-training sessions, the subjects in the fast weight loss group had an overall lower work-load of 5.3 ± 0.9 (FR) vs. 8.5 ± 2.2 (SL) hours per week. Due to the restricted energy intake (-19% ± 2% in the SL and 30% ± 4% in the FR group), both groups exhibited similar body weight (BW) and fat loss:
BW and fat mass decreased in both SR and FR by 5.6% ± 0.8% and 5.5% ± 0.7% (0.7% ± 0.8% vs. 1.0% ± 0.4%/wk) and 31% ± 3% and 21 ± 4%, respectively.
The "slow dieters" (SR) on the other hand managed - even in this phase of caloric reduction - to actually gain muscle mass:
[in the slow dieters] LBM increased in SR by 2.1% ± 0.4% (p < .001), whereas it was unchanged in FR (-0.2% ± 0.7%), with significant differences between groups (p < .01).
The observation of muscle mass increases on a relatively high volume (compared to fast dieters) training and a restricted, yet not energy depriving diet regimen is of utmost importance for athletes and physical culturists, as well, since they demonstrate that losing fat while building muscle, which is commonly touted as a metabolic impossibility aside from steroid users or absolute beginners, is very well possible even in trained and supposedly drug-free athletes.

Bottom line: Take it slowly and go by what you see in the mirror (body composition) and lift and in the gym (performance). And if you do not have access to a DEXA unit, such as the one the scientists used in this study to measure body fat percentages, a simple measuring tape is an effective tool to judge weight loss / muscle mass as well - your belly shrinks and your shoulders get broader? What else could you ask for?