Objective Obesity alters protein metabolism in skeletal muscle, but consistent evidence is lacking. We compared muscle protein synthesis in adults with obesity to that in lean controls in the fasted state and during an amino acid infusion. Methods Ten subjects with obesity (age 36 ± 3 years; BMI 34 ± 1 kg/m2) and ten controls (age 35 ± 3 years; BMI 23 ± 1 kg/m2) received an infusion of L-[2,3,3,4,5,5,5,6,6,6-2H10]leucine (0.15 μmol/kg FFM/min) to measure muscle protein synthesis after an overnight fast and during amino acid infusion. Results Despite greater muscle mTOR phosphorylation (P ≤ 0.05), fasted-state mixed-muscle and mitochondrial protein synthesis were lower in subjects with obesity (P ≤ 0.05). However, the change in mixed-muscle protein synthesis during the amino acid infusion was 2.7-fold greater in subjects with obesity (P ≤ 0.05), accompanied by a greater change in S6K1 phosphorylation (P ≤ 0.05). The change in mitochondrial protein synthesis did not differ between groups (P > 0.05). Conclusions Adults with obesity have reduced muscle protein synthesis in the fasted state, but this response is compensated for by a greater change in overall muscle protein synthesis during amino acid infusion.

Depression odds vary depending on HNC anatomic site, and one in four patients with laryngeal cancer may be depressed. Since depression is prevalent in this survivor cohort, it is important that psychosocial assessment and intervention are integrated into mainstream clinical care for patients with HNC.

SummaryDuring aging, decreases in energy expenditure and locomotor activity lead to body weight and fat gain. Aging is also associated with decreases in muscle strength and endurance leading to functional decline. Here, we show that lifelong deletion of ghrelin prevents development of obesity associated with aging by modulating food intake and energy expenditure. Ghrelin deletion also attenuated the decrease in phosphorylated adenosine monophosphate‐activated protein kinase (pAMPK) and downstream mediators in muscle, and increased the number of type IIa (fatigue resistant, oxidative) muscle fibers, preventing the decline in muscle strength and endurance seen with aging. Longevity was not affected by ghrelin deletion. Treatment of old mice with pharmacologic doses of ghrelin increased food intake, body weight, and muscle strength in both ghrelin wild‐type and knockout mice. These findings highlight the relevance of ghrelin during aging and identify a novel AMPK‐dependent mechanism for ghrelin action in muscle.

These data suggest that DOX may inhibit mTORC1 activity and reduce MHCI and MHCIIa fiber size, potentially through elevated REDD1, and that exercise may provide a therapeutic strategy to preserve skeletal muscle size during chronic DOX treatment.