This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
The primary action of leptin is: 
Select and explain. 
A. To increase food intake, B. To decrease food intake, C. To increase gastric contraction, D. To increase intestinal motility
B: To decrease food intake
Answer: B: To decrease food intake 
Explanation: LEPTIN It is a 167 aa peptide secreted from adipocytes, blood leptin level reflects total body fat. Its primary action: To decrease food intake. It in CNS decreases NPY and alpha MSH. Leptin deficiency may lead to obesity. Ref: Sleisenger and Fordtran's, Edition-9, Page-8.