Prevention of genetic fa/fa obesity with an ephedrine-methylxanthines thermogenic mixture.

A thermogenic mixture containing ephedrine and methylxanthines was administered to 8-wk-old genetically obese fa/fa rats (O-E/Mx group) for a period of 15 wk. Their energy balance and the final body composition were compared with an untreated ad libitum-fed (O-AL) group, as well as to other fa/fa obese animals that were either pair fed to lean controls (O-PF group), or that were food restricted to such an extent they maintained a similar body weight to that of lean animals (O-WF group). Energy intake was elevated above lean or O-PF levels by approximately 27 and 10% in the O-AL and O-E/Mx groups, respectively, but lower by 18% in the O-WF group. Energy expenditure, compared with the lean values, was 10% higher in both the O-AL and O-E/Mx groups, but reduced by 13 and 30% in the O-PF and O-WF groups, respectively. The gain in body energy and the efficiency of energy deposition remained elevated above the lean values by 2.3- to 3.5-fold in the O-AL, O-PF, and O-WF groups but were reduced to lean levels in the O-E/Mx groups. These studies indicate that, unlike food restriction, the ephedrine-methylxanthine mixture prevents or arrests the development of the obesity in the fa/fa mutant by normalizing their energetic efficiency to that of the lean.