Dietary fat is an important determinant of palatability and energy density in a wide variety of foods. The appetite for fat can be traced to both unlearned attraction to orosensory factors and learned appreciation of high-fat foods based on postoral factors. While these two factors normally operate together, they can be separated experimentally by various techniques. This chapter describes the appetite for dietary fat as a function of oral and postoral effects, and discusses the emerging information about the genetics of fat appetite. Much of the data comes from animal models (rats and mice), but studies of human fat appetite are also noted.
Understanding the basis for fat appetite is important, as it is thought to contribute to the increasing levels of obesity in affluent nations. This stems in part from the higher metabolizable energy content of fat, which is more than twice that of carbohydrate and protein. Foods that are high in fat are thus more energy-dense than lower-fat foods (an exception might be high-fat foods that are also high in water or fiber content). Inexpensive, palatable high-fat foods are widely available. In addition, high-fat food is often found to be less satiating than an equal volume of high-carbohydrate food, which can exacerbate the overconsumption of high-fat foods.
The measurement of appetite for fat can be done by comparing intake of fat to that of other foods presented at the same time (preference) or by absolute amounts consumed, as compared to other foods offered at other times (acceptance). A potential drawback of foods with a mixture of nutrients is that it is difficult to ascribe preference or acceptance to particular components of the food. Accordingly, much of the work that evaluates fat appetite uses isolated nutrients to simplify the analysis. However, foods can be constructed to vary in fat and carbohydrate content, while holding the other nutrients constant, which makes them reasonable alternatives to single-nutrient analysis.
Copyright © 2010, Taylor & Francis Group, LLC.