Weight loss following LH lesions independent of changes in motor activity or metabolic rate.

Lesions in the lateral hypothalamus (LH) which resulted in aphagia and a significant loss in body weight, did not reduce either the running wheel activity or the stabilimeter activity of the animals. Following recovery, the animals failed to regain the lost weight. They had normal food and water intakes under ad lib conditions, and ate food when water deprived. They did not drink when deprived of food. Both control and LH animals also had higher than normal oxygen consumption rates. However, the LH group was not higher than the controls postoperatively. These data argue against their being a unitary LH lesion syndrome and suggest that the chronic weight loss seen in animals with LH lesions is not a secondary consequence either of having disrupted the pituitary-thyroid axis, or of having changed the animals' spontaneous activity levels.