This study investigated the influence of dietary supplementation with L-carnitine on metabolic rate, fatty acid oxidation, weight loss and lean body mass (LBM) in overweight cats undergoing rapid weight reduction. Thirty-two healthy, neutered, colony-housed cats were fed an energy-dense diet unrestricted for six months, then randomly assigned to four groups and fed a weight-reduction diet supplemented with 0 (control), 50, 100 or 150 μg of carnitine/g of diet. Following weight loss, cats were allowed unrestricted feeding of the energy-dense diet to investigate weight gain after test diet cessation.

Median weekly weight loss in all groups was 1.3%, with no difference among groups in overall or cumulative percentage weight loss. During restricted feeding, the resting energy expenditure-to-LBM ratio was significantly higher in cats that received L-carnitine than in those that ate the control diet. Respiratory quotient was significantly lower in cats that received L-carnitine on day 42, compared with pre-diet, and in all cats that received L-carnitine compared with the control group.

A significant increase in palmitate flux rate in cats fed the diet with 150 μg of carnitine/g relative to the control group on day 42 corresponded to significantly increased stoichiometric fat oxidation in the L-carnitine group (over 62% vs. 14% for the control group). Weight gain (as high as 28%) was evident within 35 days after unrestricted feeding was reintroduced.

Dietary L-carnitine supplementation appeared to have a metabolic effect in overweight cats undergoing rapid weight loss that facilitated fatty acid oxidation.

Source : S.A. Center et al., 2012. Influence of dietary supplementation with L-carnitine on metabolic rate, fatty acid oxidation, body condition and weight loss in overweight cats. AJVR 73: 1002-1015. doi: 10.2460/ajvr.73.7.1002