Trial results for a study investigating the regulation of muscle protein phenotype in humans with Obesity were posted on ClinicalTrials.gov on 2025-11-05. The study reported that whole-muscle protein synthesis averaged 0.004 %/hr (Standard Deviation 0.011) in participants with obesity, compared to 0.015 %/hr (Standard Deviation 0.005) in lean participants.
Background
Obesity is associated with various health outcomes, including alterations in muscle structure and function. A notable change in muscle in individuals with obesity is an altered muscle fiber type profile, specifically a reduced proportion of Type I fibers. This shift is linked to adverse health outcomes related to obesity. These alterations can be connected to changes in the expression of myosin heavy chain (MHC) protein isoforms in the skeletal muscle. The study aimed to investigate the metabolism of muscle MHC isoforms to understand the biological mechanisms underlying this disrupted expression pattern in the muscle of humans with obesity.
Trial design
This completed study, designated as Phase NA, enrolled 48 participants to investigate the condition of Obesity. The trial did not list specific interventions, focusing instead on understanding biological mechanisms. The study compared participants with obesity to lean participants. No primary outcomes were listed for this study.
Key results
The trial reported several key measurements comparing participants with obesity and lean participants:
- Whole-Muscle Protein Synthesis:
- Participants with Obesity: Mean of 0.004 %/hr (Standard Deviation 0.011)
- Lean participants: Mean of 0.015 %/hr (Standard Deviation 0.005)
- Synthesis Rates of the Three Myosin Heavy Chain Isoforms (MHC I, MHC IIa, and MHC IIx):
- Participants with Obesity: Mean of 0.005 %/hr (Standard Deviation 0.001)
- Lean participants: Mean of 0.006 %/hr (Standard Deviation 0.001)
- Participants with Obesity: Mean of 0.004 %/hr (Standard Deviation 0.001)
- Lean participants: Mean of 0.005 %/hr (Standard Deviation 0.001)
- Messenger RNA (mRNA) Expression of Three Myosin Heavy Chain Isoforms (MHC I, MHC IIa, and MHC IIx):
- Participants with Obesity: Mean of 1.1 Arbitrary Units (Standard Deviation 0.5)
- Lean participants: Mean of 1.0 Arbitrary Units (Standard Deviation 0.4)
- Participants with Obesity: Mean of 0.5 Arbitrary Units (Standard Deviation 0.2)
- Lean participants: Mean of 0.6 Arbitrary Units (Standard Deviation 0.3)
What this means
The results indicate a significantly lower rate of whole-muscle protein synthesis in individuals with obesity compared to lean individuals. This finding contributes to the understanding of metabolic changes in muscle associated with obesity. While synthesis rates for specific myosin heavy chain isoforms and their mRNA expression showed some differences between groups, the most pronounced distinction was in overall whole-muscle protein synthesis. These mechanistic insights can inform future research into interventions aimed at modulating muscle protein metabolism in the context of obesity to potentially mitigate adverse health outcomes.
Source
The information regarding these trial results was obtained from ClinicalTrials.gov, a public database of clinical studies. The results for the study NCT04700800, titled "Regulation of Muscle Protein Phenotype in Humans With Obesity", were posted on 2025-11-05 on clinicaltrials.gov.