Dietary modulation of ghrelin and leptin and gorging behavior after weight loss in the obese Zucker rat.

In this study, we measured ghrelin and leptin in obese Zucker rats after weight loss induced by calorie restriction using either a low-fat (LF) or high-energy palatable (HEPa) diet. After weight loss, the animals were refed lab chow and offered one hour-palatable test meals on the second and fifteenth days of refeeding. Both LF and HEPa rats lost 10% of their initial body weight (P<0.0001). Plasma ghrelin increased with calorie restriction in both groups (P<0.002) with a tendency to a higher increase in the HEPa group while plasma leptin decreased only in the LF group (P<0.01). Both groups ate the same quantity of chow during refeeding and both groups gorged on palatable diet during test meals at a very high constant intensity in HEPa rats. After one week of refeeding, ghrelin levels remained elevated in HEPa rats (+33.2%; P<0.001) while returning to baseline in LF rats. Plasma leptin remained low in LF rats. We conclude that weight loss on a palatable diet is possible if total energy intake is controlled. After stopping restriction, when a palatable diet is available, observed gorging might be dependent on specific ghrelin and leptin changes.