Effects of twenty days of the chetogenic diet on metabolic and respiratory parameters in healthy subjects.

Purpose: The effects of the ketogenic diet (KD) on weight loss, metabolic, and respiratory parameters were investigated in healthy subjects. Methods: Thirty-two healthy subjects were randomized into two groups. The KD group followed a ketogenic diet for 20 days (KD t0–t20), then switched to a low-carbohydrate, no-ketogenic diet for 20 days (KD t20–t40), and finally was on a Mediterranean diet (MD) for 2 more months (KD t40–t2m). The MD group followed a MD for 20 days (MD t0–t20), then followed a MD of 1400 kcal over the next 20 days (MD t20–t40), and completed the study with the MD for 2 months (MD t40–t2m). Body weight, body fat, respiratory rate, and respiratory gas parameters (including respiratory exchange ratio (RER) and carbon dioxide end-tidal partial pressure (PETCO2), oxygen uptake (VO2), carbon dioxide production (VCO2), and resting energy expenditure (REE)) were measured at each point. Results: A significant decrease (p < 0.05) in RER was observed after 20 and 40 days in the...