Ketogenic diet improves gas exchange, sleep apnoea in obesity hypoventilation syndrome

Adherence to a ketogenic diet helps manage hypercapnia and sleep apnoea in patients with obesity hypoventilation syndrome (OHS), claims a nonrandomized crossover study.

A team of investigators conducted a single-arm crossover clinical trial to assess the effect of a ketogenic diet on CO₂ levels in patients with OHS. They instructed participants to adhere to 1 week of regular diet, 2 weeks of ketogenic diet, followed by 1 week of regular diet in an ambulatory setting. Adherence was evaluated using capillary ketone levels and continuous glucose monitors.

Finally, the investigators measured blood gases, calorimetry, body composition, metabolic profiles, and sleep studies at weekly visits. They assessed the outcomes using linear mixed models.

Twenty participants completed the study. Their blood ketones rose from 0.14 mmol/L during regular diet to 1.99 mmol/L (p<0.001) after 2 weeks of ketogenic diet. Adherence to a ketogenic diet also reduced venous CO₂ levels by 3.0 mm Hg (p=0.008), bicarbonate by 1.8 mmol/L (p=0.001), and weight by 3.4 kg (p<0.001). Significant improvements were seen in sleep apnoea severity and nocturnal oxygen levels.

Furthermore, ketogenic diet reduced respiratory quotient, fat mass, body water, glucose, insulin, triglycerides, leptin, and insulin-like growth factor 1. Resumption of a regular diet led to rebound hypercapnia. CO₂ lowering showed dependence on baseline hypercapnia and correlated with circulating ketone levels and respiratory quotient.

Notably, adherence to the ketogenic diet was well tolerated.

“OHS causes hypercapnia, which is often refractory to current therapies,” the investigators said.