We aimed to evaluate the effect of the Mediterranean diet (MD) compared with that of a prudent diet (PD) combined with physical activity on obese OSAS patients who were treated with CPAP.

Nine hundred patients were evaluated and forty obese patients (body mass index: ≥30.0 kg·m−2) who met the inclusion criteria, with moderate to severe OSAS (apnoea-hypopnoea index: >15 and daytime sleepiness: >10) based on overnight attended polysomnography, were included in the study. After randomization, 20 followed the MD and 20 a PD for a 6-month period. All patients were counselled to increase their physical activity.

Concerning sleep parameters, only apnoea-hypopnoea index during rapid eye movement sleep (AHI/REM) was reduced to a statistically significant degree, by 18.4±17.6 in the MD group and by 2.6±23.7 in the PD group (p<0.05). The MD group showed also a greater reduction in waist circumference (WC) (−8.7±3.6), WC/height ratio (−0.04±0.02) and WC/hip ratio (−0.04±0.03), compared with the other group (−5.7±3.8, −0.03±0.02, 0.02±0.02 and −2.6±1.7, respectively, p<0.05).

Our results showed that the MD combined with physical activity for 6 months period was effective in reducing the AHI/REM without any statistical significant effect in the other sleep parameters, compared to a PD in obese adults with moderate to severe OSAS.