The comparative levels of fat and carbohydrate levels in snack foods may have an important role in making them appetising, a small rat study in Scientific Reports suggests. However, it is unclear if these properties trigger excessive food intake.

Foods that are high in calories, fats or carbohydrates may trigger excessive food intake beyond normal satiety, and this increased energy intake can result in elevated weight. These foods are thought to modulate activity within the brain reward system, as seen in previous studies in which rats were fed potato chips. It has been proposed that energy content may be a key determinant of the rewarding properties and palatability of snack food, which may drive increased feeding. However, Monkia Pischetstrieder and colleagues find that it is the ratio of fat and carbohydrate, not the absolute energy content, that seems to make certain foods highly appetising to rats.

A total of 18 rats were given access to either standard rat feed or test foods containing various levels of fat and carbohydrates. The food with a composition that most closely resembled that of potato chips were most appetising and were shown to influence brain activity patterns in regions associated with reward and addiction, although the effects were not as strong as those previously observed in rats fed on potato chips. Thus, it is likely that feeding behaviour is also influenced by other components in snack food, the authors conclude.