What is the primary effect of PYY on the body?

PYY, or peptide YY, is a hormone produced by the gut, primarily in response to food intake. Its primary effect on the body is appetite suppression. This hormone plays a crucial role in regulating energy balance by signaling to the brain to reduce hunger and increase feelings of fullness after eating. When food is consumed, PYY is released into the bloodstream and acts on the hypothalamus, where it inhibits appetite, thereby contributing to the overall process of satiety.

Research has shown that elevated levels of PYY after a meal correlate with decreased food intake, making it an important factor in weight management and obesity treatment strategies. By promoting a feeling of satisfaction from smaller amounts of food, PYY helps to prevent overeating.

The other options do not align with the primary action of PYY in the context of appetite regulation and energy homeostasis, as PYY does not serve to increase appetite, enhance digestion, or directly increase energy expenditure in a significant manner. Instead, it highlights the hormone's role in appetite regulation, reinforcing its critical function in the body’s response to food consumption.