Slower eating rate is independent to gastric emptying in obese minipigs

The aim of our study was to investigate whether the altered eating behavior observed in the context of a diet-induced metabolic syndrome is related to changes of the gastric emptying and autonomic balance. Eight adult male Göttingen minipigs were subjected during 5 months to ad libitum Western diet (WD). Several factors were compared between the lean (before WD) and obese conditions: general activity and eating behavior, gastric emptying, adiposity, glycemia and insulinemia during IVGTT, and heart rate variability (HRV). In our model, obesity did not alter the gastric emptying (258 ± 26 vs. 256 ± 14 min, P > 0.10) but induced insulin resistance: increased basal insulinemia (12.6 ± 0.8 to 36.6 ± 6.1 mU/l, P < 0.02) and reduced insulin sensitivity (4.5E−4 ± 0.7E−4 to 2.5E−4 ± 0.2E−4 min−1 per mU.l−1 of insulin, P < 0.05). The HRV and sympathovagal balance were not significantly modified (P > 0.10). Fed ad libitum with WD, animals overate durably (P < 0.001). During a 30-min meal test though, the ingestion speed, the food ingested (1076 ± 48 vs. 520 ± 52 g) and energy intake decreased in the obese condition (P < 0.05), which can be explained by the fragmentation of the daily caloric intake. These data suggest that the slower eating rate and increased number of meals observed in obese minipigs without neuropathy is independent to gastric emptying. The explanation may be sought rather in central modifications induced by obesity that might modify the food perception and/or motivation.

Research Highlights
► Obese minipigs had slower eating rate and increased number of meals.
► These animals showed normal gastric emptying and no vagal neuropathy.
► A dramatic increase of subcutaneous and visceral adiposity was observed.
► Obese minipigs had increased basal insulinemia and reduced insulin sensitivity.
► The food perception/motivation in obese minipigs might have been altered