Pre-exposed to food, infants have an unconditioned response to sugary food that tends to satisfy their appetite. Human physiology is designed to have a taste for sugary food. When it comes to dietary variability, the author says, it helps people manage the amount of calories a person can consume. One aspect is when a low-calorie dessert can interfere with your decision about how many calories or how much food you can eat. The author then argues that the use of "dietary variation" can hinder the decision to differentiate low-calorie sweeteners from high-calorie sweeteners, which can eventually lead to weight gain.