CPAP Lowers Body Weight and Improves Metabolic Syndrome in Patients With Sleep Apnea

Regular readers will be well aware of the rather strong association between obstructive sleep apnea (OSA) and excess weight. This is often a two-way street, with OSA leading to poor sleep and sleep cycle disruption, which in turn can affect daytime activity levels and (most likely) eating behaviour. In addition, the intermittent hypoxia associated with OSA has been implicated in hypertension and poor metabolic control.

A recent study by Surendra Sharma (no relation) from the All India Institute of Medical Sciences, New Delhi India, published in the New England Journal of Medicine, demonstrates the positive impact of treating OSA with CPAP on body weight and metabolic syndrome.

Sharma and colleagues, studied 86 patients, 75 (87%) of whom had the metabolic syndrome, in a double-blind, placebo-controlled trial, in which they randomly assigned patients with OSA to 3 months of therapeutic CPAP followed by 3 months of sham CPAP, or vice versa, with a washout period of 1 month in between.

CPAP treatment (vs. sham CPAP) was associated with small but significant mean decreases in blood pressure, cholesterol and triglyceride levels, as well as Hba1C levels.

Metabolic syndrome status was reversed in 13% under CPAP vs. 1% under sham treatment.

I was quite interested in seeing that there was also a small, but statistically significant reduction in body weight, BMI, and waist circumference.

Thus, as the authors note,

“We demonstrated a significant decrease in BMI and abdominal fat, by using CT, in association with CPAP therapy. These findings could be secondary to a decrease in daytime somnolence and a consequent increase in physical activity after CPAP use at night.”


“Weight loss could also be a mechanism for improvement in components of the metabolic syndrome in this study, as suggested by the correlation of the metabolic syndrome with a change in BMI. However, baseline BMI was not a determinant of response to therapy.”

The latter finding comes as no surprise given that there is a rather poor relationship between BMI and cardiometabolic risk factors (which is exactly why we came up with the Edmonton Obesity Staging System).

Overall, the findings certainly support the notion that patients presenting with excess weight and cardiometabolic risk factors should be routinely screened for OSA and that they stand to substantially benefit from its treatment.

Edmonton, Alberta

ResearchBlogging.orgSharma SK, Agrawal S, Damodaran D, Sreenivas V, Kadhiravan T, Lakshmy R, Jagia P, & Kumar A (2011). CPAP for the metabolic syndrome in patients with obstructive sleep apnea. The New England journal of medicine, 365 (24), 2277-86 PMID: 22168642