Final answer:
Ghrelin is known to increase appetite, whereas leptin generally decreases it. The hypothalamus region of the brain signals hunger and satiety, and multiple factors including psychological state, hormones, and exercise can influence appetite.
Step-by-step explanation:
Ghrelin increases appetite and leptin decreases appetite. Psychological factors such as worry and anxiety can reduce appetite due to imperfect mastication and secretion of digestive juices, whereas eating in pleasant surroundings and good company with different items can increase food consumption. Additionally, the hypothalamus region of the brain controls signals of hunger and satiety, with foods rich in fatty acids promoting satiety more effectively than those rich in carbohydrates. Hormonal levels and number of target cell receptors also play a role in influencing appetite. Another interesting factor is exercise, which can act as both an appetite stimulant and suppressant due to the body producing hormones and chemicals during physical activity that turn down appetite. Age-related changes in the digestive system can lead to appetite suppression and altering food preferences as well.