The form of classical conditioning in which a food that was once liked becomes avoided is known as taste aversion or food aversion. This occurs when an individual associates a particular food with feeling ill, leading to a conditioned response of avoiding that food in the future.

Anorexia nervosa, An aversion to food.

vision

Taste aversion is a conditioned response, which happens when a person associates a certain food with an illness or unpleasant experience; an example would be someone who can't eat apples, because they developed stomache flu shortly after eating one. The illness had nothing to do with the apple, but the person associates the two psychologically. Taste aversion can happen with any food.

Conditioned taste aversion is a learned association between the taste of a food and a negative experience, such as illness or nausea. This association can cause an individual to avoid eating that food in the future to prevent experiencing the negative outcome again.