Persistent suppression of resting energy expenditure after acute hypoxia

Short Hypoxia Does not Affect Plasma Leptin in Healthy Men under Euglycemic Clamp Conditions

“…Determination of plasma glucose concentrations and serum insulin confirmed that respective blood levels remained constant after having reached the equilibrium and did not differ between hypoxic and normoxic conditions throughout the study (Figure 1). Also, as already published [3], norepinephrine concentrations did not differ significantly between the two sessions ( P = .3) whereas epinephrine levels were significantly higher under the hypoxic condition as compared with the control session ( P < .01). The glucose infusion rates were significantly lower during the hypoxic as compared to the normoxic period [2].…”

“…So eventually our negative findings may simply reflect an insufficient duration and the extent of hypoxia to affect leptin secretion. Notwithstanding, our study design has been established to induce clinically relevant changes in other features of the metabolic syndrome [2, 3] and is therefore an adequate approach to gain first insight into the effects of acute hypoxia in this context in humans. In addition, this is the first study investigating the effects of acute hypoxia on leptin concentrations controlling for fundamental influencing factors in healthy men.…”

“…We could previously demonstrate, based on an experimental human in vivo design established in our group, that 30 minutes of oxygen desaturation to 75% are sufficient to induce features of the metabolic syndrome such as glucose intolerance [2, 3] and respective changes in sympathetic activation [2, 3], resting energy expenditure [2, 3], and vascular endothelial growth factor (VEGF) levels [4], a hormone which has been assumed to play a role in the pathogenesis of the metabolic syndrome [5]. …”

“…In order to clarify if hypoxia affects circulating leptin concentrations in humans, we experimentally induced a short hypoxic period as compared to normoxic condition in healthy normal weight participants according to our established study design which has been demonstrated to induce clinically relevant changes in energy and hormone metabolism [2, 3]. Oxygen saturation of 75%, as applied in our study, corresponds to a physiological state at approximately an altitude of 3500–4000 m. To control for common biases known to influence leptin metabolism, we performed our study at rest.…”

Abdominal Fat and Sleep Apnea: the Chicken or the Egg?

“…We found that experimentally induced hypoxia leads to a persistent suppression of resting energy expenditure in healthy subjects (4), an aspect centrally involved in the development and worsening of obesity, which is most likely also of relevance for weight gain in OSA.…”