L-Carnitine

The body makes L-carnitine from the amino acids lysine and methionine and uses it to carry fats into cells to be burned. Meat is the main source in food. It’s often added to weight-control foods, on the idea that it helps pets lose fat rather than muscle.

The evidence is limited. In one study of 24 obese pet cats on a weight-loss diet, those given L-carnitine as a daily liquid lost weight somewhat faster. That’s a small study at a set dose, and it doesn’t show what the amount in a normal food does. Weight loss needs a plan: ask your veterinarian.