Manipulation of Diet to Alter Appetite

Abstract

Reductions in caloric intake invariably result in compensatory increases in feelings of hunger. However, these negative consequences of energy restriction can potentially be managed through the consumption of a satiating low energy diet. Experimental data clearly demonstrate that differing foods, manipulated for the macronutrient content, energy density, and portion size can produce marked changes in subsequent feelings of satiety. The effects are dependent in the most part on differences in the sensory experience and cognitive impact of these foods, and their physiological impact on episodic physiological satiety mechanism such as gastrointestinal function and gut peptide release. It is generally accepted that satiety hierarchy exists between the macronutrients with protein – carbohydrate – fat. However, despite this, the effects of various macronutrients on subsequent energy intake are more equivocal. The effects of differing forms of protein on appetite in particular are poorly understood. Dietary fats are considered to be a key contributor to obesity despite the strong preabsorptive satiety signals generated by free fatty acids. This paradox may be explained by passive overconsumption of the energy dense high fat food and palatability-driven active overconsumption. As with fats, the effect of carbohydrates on appetite depend heavily on their form, with simple carbohydrates producing pronounced but transient effects on appetite regulation and complex carbohydrates producing more sustained changes in appetite. Moreover, nondigestible carbohydrates have a variety of effects on appetite depending on their form (viscosity, solubility, and fermentability). Decreasing energy density, with or without accompanying changes in portion size, also appear effective strategies for reducing caloric intake at least over a number of days. To conclude, dietary manipulations of macronutrient content, energy density, and portion size do impact on appetite expression and these have the potential to produce sustainable changes in caloric intake needed for weight control. However, the long-term effects of such dietary manipulations on appetite remain to be robustly demonstrated.