With regards to short term weight loss, a high protein diet will result in less muscle loss. Also, because this was an acute study focused on rapid weight loss, performance parameters didn’t change considerably. But in terms of how people actually “feel” on that kind of diet, the results aren’t too promising. If you’re a bodybuilder dieting for a contest, these results give you a great reason to keep your protein high – or if you’re an athlete trying to lose a little fat before the season, these results are probably applicable to you as well.
But if you need to reduce your total calorie intake to 60% of normal to achieve your desired weight loss, as this study examined, then you’re probably a fattie anyway, and who cares what works for you. show a little discipline and get rid of the beer-gut before you go looking at studies on weight loss.
Med Sci Sports Excersi 2010 Feb;42(2):326-37.
Increased protein intake reduces lean body mass loss during weight loss in athletes.
Mettler S, Mitchell N, Tipton KD.
School of Sport and Exercise Sciences, University of Birmingham, Birmingham, United Kingdom.
To examine the influence of dietary protein on lean body mass loss and performance during short-term hypoenergetic weight loss in athletes.
In a parallel design, 20 young healthy resistance-trained athletes were examined for energy expenditure for 1 wk and fed a mixed diet (15% protein, 100% energy) in the second week followed by a hypoenergetic diet (60% of the habitual energy intake), containing either 15% (approximately 1.0 g x kg(-1)) protein (control group, n = 10; CP) or 35% (approximately 2.3 g x kg(-1)) protein (high-protein group, n = 10; HP) for 2 wk. Subjects continued their habitual training throughout the study. Total, lean body, and fat mass, performance (squat jump, maximal isometric leg extension, one-repetition maximum (1RM) bench press, muscle endurance bench press, and 30-s Wingate test) and fasting blood samples (glucose, nonesterified fatty acids (NEFA), glycerol, urea, cortisol, free testosterone, free Insulin-like growth factor-1 (IGF-1), and growth hormone), and psychologic measures were examined at the end of each of the 4 wk.
Total (-3.0 +/- 0.4 and -1.5 +/- 0.3 kg for the CP and HP, respectively, P = 0.036) and lean body mass loss (-1.6 +/- 0.3 and -0.3 +/- 0.3 kg, P = 0.006) were significantly larger in the CP compared with those in the HP. Fat loss, performance, and most blood parameters were not influenced by the diet. Urea was higher in HP, and NEFA and urea showed a group x time interaction. Fatigue ratings and “worse than normal” scores on the Daily Analysis of Life Demands for Athletes were higher in HP.
These results indicate that approximately 2.3 g x kg(-1) or approximately 35% protein was significantly superior to approximately 1.0 g x kg(-1) or approximately 15% energy protein for maintenance of lean body mass in young healthy athletes during short-term hypoenergetic weight loss.