Impact of Whey and Soy Protein Ingestion in Conjunction With Energy Restriction in Overweight/Obese Individuals

Impact of Whey and Soy Protein Ingestion in Conjunction With Energy Restriction in Overweight/Obese Individuals

Molecular Events Underpinning Changes in Tissue Metabolism With Whey and Soy Ingestion in Energy Restriction in Overweight/Obese Adults

It is known that dieting (restricted energy intake) without resistance training leads to a reduced metabolic rate, and the loss of both fat and muscle mass. When exercise is not included in a period of restricted energy intake, the degree to which muscle mass is lost is highly dependent upon protein consumption. Whey protein is a high quality protein isolated from milk and is known to stimulate new protein synthesis for all proteins in your body. Previous research has established that the consumption of whey protein has been correlated with retaining muscle mass while stimulating fat loss. However, the mechanisms behind these findings is still unknown. The purpose of this study is to establish a mechanistic underpinning to the efficacy of whey protein versus soy protein and a carbohydrate control (maltodextrin), in promoting fat mass loss and lean mass retention during a period of short-term controlled dietary energy deficit (-750 kcalories/day).

obesity, overweight, muscle, protein, muscle protein synthesis, muscle protein breakdown, whey, soy, caloric restriction

Carbohydrate & 750 kcal dietary restriction while they receive a daily supplement (2 x 25 g) of maltodextrin (no protein) for 14 days. Weight loss.

Whey protein & 750 kcal dietary restriction while they receive a daily supplement (2 x 25 g) of WPI for 14 days. Weight loss.

Soy protein & 750 kcal dietary restriction while they receive a daily supplement (2 x 25 g) of SPC for 14 days. Weight loss.

Muscle protein synthesis rate and lipolytic rate as measured using stable isotope and glycerol infusions.

Transcriptomic changes (via gene profiling) associated with the effects of whey on lipogenic and lipid oxidative genes, and protein synthetic pathways in muscle.

Inclusion Criteria: Aged 35 to 55 years old Moderately Obese/Overweight (body mass index > 25 and < 42 kg/m2) Healthy Non-smoker Exclusion Criteria: Suffer from type 2 diabetes, hyperlipidemia, or thyroid dysfunction Taking medications Having an unstable weight in the past 4-6 months, or dieting at some time during the past 6 months Taking weight loss products or aids (including energy drinks)

Hector AJ, Marcotte GR, Churchward-Venne TA, Murphy CH, Breen L, von Allmen M, Baker SK, Phillips SM. Whey protein supplementation preserves postprandial myofibrillar protein synthesis during short-term energy restriction in overweight and obese adults. J Nutr. 2015 Feb;145(2):246-52. doi: 10.3945/jn.114.200832. Epub 2014 Dec 17. Erratum In: J Nutr. 2015 Jun;145(6):1373.

Paschalis V, Theodorou AA, Margaritelis NV, Kyparos A, Nikolaidis MG. N-acetylcysteine supplementation increases exercise performance and reduces oxidative stress only in individuals with low levels of glutathione. Free Radic Biol Med. 2018 Feb 1;115:288-297. doi: 10.1016/j.freeradbiomed.2017.12.007. Epub 2017 Dec 9.

Churchward-Venne TA, Breen L, Di Donato DM, Hector AJ, Mitchell CJ, Moore DR, Stellingwerff T, Breuille D, Offord EA, Baker SK, Phillips SM. Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial. Am J Clin Nutr. 2014 Feb;99(2):276-86. doi: 10.3945/ajcn.113.068775. Epub 2013 Nov 27.