Short-term regulation of food intake controls what, when and how much we eat during a single day or a meal, and is regulated by mechanical stimulation and release of peptides in the gastrointestinal (GI) tract. Both composition and structure of food affect peptide release. Many of these peptides inhibit also GI motility. Macronutrients stimulate GI peptides in different ways. Of special interest are the peptides ghrelin, cholecystokinin, glucagon-like peptide 1 and peptide YY. The amount of existing literature is, however, limited, and the results somewhat contradictory, which makes it challenging to make conclusions about the exact role of different macronutrients.