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Updated: Oct 7, 2025

Assessing Energy Substrate Oxidation In Vitro with 14CO2 Trapping
Published on: March 23, 2022
Metabolic rate and substrate oxidation of young males with obesity at the different sleep stages
Xiaochang Cai1, Haiying Quan1, Dandan Chang1
1School of Biomedical Engineering, Capital Medical University, No.10 Xitoutiao, You An Men Wai, Fengtai District, Beijing 100069, China; Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, No.10 Xitoutiao, You An Men Wai, Fengtai District, Beijing 100069, China.
Objective:
Insufficient and poor-quality sleep among young adults is closely related to obesity and may impact metabolic processes. The mobilization and use of endogenous substrates during sleep, especially fat oxidation, is essential for energy metabolism. This study investigated whether there are differences in sleep structure, metabolic rate, substrate oxidation, and the respiratory quotient (RQ) between young males with normal weight and obesity according to sleep stages and overnight sleep.
Methods:
Fifteen young males with normal weight and fifteen with obesity posited electrodes of polysomnography (PSG) and slept in the metabolic chamber for estimation of sleep structure, sleep metabolic rate (SMR), carbohydrate oxidation (CHOO), fat oxidation (FATO), and RQ. Fat-free mass (FFM) was measured by bioelectrical impedance analysis.
Results:
The sleep period time (p = 0.038) and total sleep time (p = 0.032) were significantly shorter in the obesity group than in the normal-weight group. The obesity group also had a longer sleep latency (p = 0.034) and more sleep-turning events (p = 0.018). CHOO/FFM and the RQ were higher in the obesity group while FATO/FFM was significantly higher in the normal-weight group. FATO/FFM was also higher in the normal-weight group in each sleep stage whereas the RQ was higher in the obesity group (p < 0.05).
Conclusions:
Young males with obesity showed lower fat oxidation and more dominant carbohydrate-derived fuel oxidation than normal-weight during sleep and experienced shorter sleep periods and total sleep time.
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