Answer to Question 1
Answer: Ablation of the LH produces reduced eating and drinking, which reflects cell damage rather than damage to axons of passage. Electrical stimulation of the LH elicits eating. Cells within the LH secrete MCH as well as orexin, two neuropeptides that induce eating. Damage to the VMH produces overeating to obesity while stimulation of the VMH suppresses eating.
Answer to Question 2
Answer: The genetic literature suggests that there is a strong heritability factor for obesity and that family environment, which would be expected to transmit eating habits, has a remarkably small effect. Although no simple genetic defect has been found for obesity, it is clear that there are important differences in metabolism that result in some persons easily gaining weight during periods of access to high-energy diet, while others appear to be resistant to gaining weight. The rate of obesity has increased rapidly, faster than could be explained by a genetic mechanism. Recent studies suggest that the use of high fructose as a sweetener has facilitated weight gain.
A silver agouti guinea pig eating grass
Elephant using its feet to crush a watermelon before eating it.
Cotton-top tamarin eating a grasshopper
Presynaptic modulation at axoaxonic synapses.
Select Signs and Symptoms of Feeding and Eating Disorders