Altered Postprandial Responses in Gastric Myoelectrical Activity and Cardiac Autonomic Functions in Healthy Obese Subjects

Background It is unknown whether gastric myoelectrical activity (GMA) and autonomic functions are altered in obesity. The aims of this study were to investigate GMA and autonomic functions in obese subjects and to compare their responses to different meals with lean subjects. Methods The study was performed in 12 lean and 12 obese subjects. GMA was measured using electrogastrography, and autonomic functions were assessed using spectral analysis of heart rate variability. Results The study achieved the following key results: (1) Compared to lean subjects, obese subjects showed unaltered gastric slow waves at baseline but enhanced responses to both fatty and protein meals. The lean subjects showed a reduced percentage of normal gastric slow waves with a fatty meal, which was not seen in obese subjects; lean subjects showed no changes in the dominant frequency or power of the gastric slow waves with a protein meal, whereas both of these parameters were increased in obese subjects. (2) Autonomic functions were altered in obese subjects in both fasting and fed states. Obese subjects showed an increased sympathetic activity in the fasting state, but absence of a normal postprandial response in sympathovagal balance to both fatty and protein meals. Conclusions The findings on gastric slow waves demonstrate that obese subjects are more receptive to fatty meals and more responsive to protein meals. Obese subjects have impaired autonomic functions in both fasting and fed states. The alterations in gastric and autonomic functions may contribute to eating disorders in the obese.