La whey, presque 2 fois plus efficace que le soja pour préserver l'anabolisme musculaire au régime
Whey protein supplementation preserves postprandial muscle protein synthesis during short term energy restriction in
overweight/obese adults
Amy J. Hecto Applied Physiology, Nutrition, and Metabolism
Volume: 39, Number: S1 (2014) S21
Increased protein intake during diet-induced weight loss results in
improved lean mass retention and fat mass loss. The physiological
mechanism for this effect and the impact of protein quality on body
composition during weight loss are uninvestigated. The aim of this
study was to assess the mechanisms by which different quality proteins
(whey or soy) affect muscle protein synthesis (MPS), whole-body
lipolysis and body composition during a short term hypoenergetic
diet. Forty adult men and women (35-65 years, BMI 28-50) completed a
14-d hypoenergetic diet while being supplemented twice daily with
whey or soy protein, or carbohydrate control. Before and after the
dietary intervention participants completed an infusion trial with
a primed continuous infusion of L-[ring-13C 6 ] phenylalanine and
[2H 5 ]-glycerol to measure postabsorptive and postprandial (following
whey, soy or carbohydrate ingestion) rates of MPS and whole body lipolysis.
Changes in fat and lean mass were measured by DXA. Before weight
loss, postprandial MPS rates were stimulated to a greater extent following
ingestion of whey protein than soy and carbohydrate. Following the
14-d weight loss, the postabsorptive rates of MPS decreased by 15±13% in
the whey group, 26±13% in soy and 19.6±13% in the carbohydrate groups
P>0.05. Postprandial rates of MPS were reduced by 8.6±0.7% in the whey
group, which was significantly less than the reduction in soy (28±5%) and
carbohydrate groups (31±5%, P=0.013) following the 14-day weight loss.
Whole body lipolysis was suppressed with feeding, but responded to
whey and soy supplementation in the same manner before and after the
14-day intervention. Total weight loss (-2.29±0.18 kg), fat mass loss
(-1.19±0.16 kg) and lean mass loss (-0.81±0.24 kg) did not differ between
groups. These results demonstrate the impact of protein quality on MPS
during energy restriction, and may be of importance in the development
of nutritional strategies to promote lean mass retention during weight
loss.