Which of the following are involved in decreased food intake and weight loss?
(a) Insulin
(b) Leptin
(c) Cholecystokinin
(d) Orexin

Choose the correct answer from the options given below:

Correct option is B

The correct answer is A, B and C only.
1. Insulin, leptin, and cholecystokinin (CCK) are involved in decreased food intake and contribute to weight loss by regulating appetite and energy balance.

2. Insulin: While primarily known for its role in regulating blood sugar levels, insulin also plays a role in decreasing food intake and promoting satiety. High levels of insulin after eating signal the body to stop eating.

3. Leptin: This hormone, produced by fat cells, signals the brain to decrease food intake and increase energy expenditure. When fat stores are high, leptin levels increase, leading to a decrease in hunger and food intake.

4. Cholecystokinin (CCK): This hormone is released by the intestines after food intake and helps reduce food consumption by promoting satiety. It signals the brain to stop eating and slows down gastric emptying.

Information Booster

1. Insulin:
1.1 Insulin, produced by the pancreas, is primarily responsible for regulating glucose metabolism. However, it also helps in appetite regulation.
1.2 High insulin levels, especially after meals, promote feelings of satiety and decrease appetite.
1.3 Insulin's effect on food intake is part of its broader role in regulating energy homeostasis.

2. Leptin:
2.1 Leptin is a hormone produced by adipose tissue (fat cells) and plays a key role in regulating energy balance.
2.2 Leptin signals the hypothalamus in the brain to reduce appetite and increase energy expenditure, particularly when fat stores are sufficient.
2.3 Low leptin levels are associated with increased hunger, while high levels lead to reduced appetite and increased metabolic rate, helping to prevent further weight gain.
2.4 Leptin resistance can occur in obesity, where despite high leptin levels, the brain does not respond to the hunger-suppressing signals.

3. Cholecystokinin (CCK):
3.1 CCK is a peptide hormone released from the small intestine in response to food intake, particularly fatty foods and proteins.
3.2 CCK promotes satiety by slowing gastric emptying, enhancing digestion, and signaling the brain to stop eating.
3.3 CCK has been shown to have appetite-suppressing effects, which helps reduce food intake and contributes to weight loss.

Additional Information

Orexin (Option D):
4.1 Orexin (also known as hypocretin) is a neuropeptide that is involved in increasing appetite and energy consumption.
4.2 Unlike insulin, leptin, and CCK, orexin stimulates appetite and food-seeking behavior, rather than reducing it.
4.3 Orexin is more closely associated with increased food intake and wakefulness rather than weight loss or decreased food intake.
4.4 Elevated orexin levels are linked to increased hunger and could contribute to obesity rather than weight loss.