Calorie Restriction, Protein Supplementation and Metabolic Health (CRPS)

Comparador Ativo: Perda de peso com ingestão normal de proteínas

Comportamental: Weight loss with normal protein intake

Goal of 8 to 10% weight loss while consuming the recommended daily allowance of protein (i.e, 0.8 grams of protein per kg body weight per day).

Sem intervenção: Weight maintenance

Weight maintenance with normal protein intake

Experimental: Weight loss with protein supplementation

Comportamental: Weight loss with protein supplementation

Goal of 8 to 10% weight loss while consuming 150% of the recommended daily allowance of protein (i.e., 1.2 grams of protein per kg body weight per day).

Change in muscle volume

Thigh muscle volume will be measured by magnetic resonance imaging (MRI)

Change in muscle strength

Muscle strength will be evaluated by administering maximum one repetition strength and isokinetic strength tests.

Changes in bone mineral density and bone mineral content

Total bone mass and total body and regional bone mineral density will be evaluated by using dual X-ray energy absorptiometry (DXA).

Mudança nas populações bacterianas encontradas nas fezes

Change in insulin sensitivity

Insulin sensitivity (glucose rate of disappearance [Rd] during a hyperinsulinemic-euglycemic clamp procedure) will be evaluated in a subset of 10 participants per group because power analysis has determined that this number is sufficient to detect a 25% difference between groups assuming 80% power, an alpha value of 0.05 and an average baseline insulin-stimulated glucose Rd of 2,590 ± 492 µmol/min, the average ± SD insulin stimulated glucose Rd the investigators have measured during the past 20 y in obese subjects. In the investigators' experience (Kirk et al., 2009 and Magkos et al., 2016), the weight loss induced increase in insulin stimulated glucose Rd is ~50%.

Change in muscle protein metabolism

Rates of muscle protein synthesis, breakdown and net protein balance will be assessed during postabsorptive conditions and when insulin and/or amino acid concentrations are elevated.

Change in cell proliferation (growth) rates in the colon

Colon cell proliferation rates will be determined using stable isotope labelled tracer methods in conjunction with sigmoid colon biopsy samples

Determine the acute effect of whey protein ingestion on skeletal muscle insulin sensitivity

Insulin sensitivity will be evaluated using the hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotope labeled tracer infusions

Determine the acute effect of whey protein ingestion on muscle protein metabolism

Rates of muscle protein synthesis, breakdown and net protein balance will be assessed using stable isotope labeled tracer methods during postabsorptive conditions and during insulin infusion with or without whey protein ingestion