The relationship between dietary energy density and energy intake
Section snippets
What is energy density?
Energy density is the amount of energy (calories or joules) in a particular weight of food. It is generally presented as the number of calories per gram of food (kcal/g). Energy density values, which are influenced by the macronutrient composition and moisture content of foods and beverages, range from 0 kcal/g to 9 kcal/g. Because of its high energy content, fat (9 kcal/g) influences energy density values more than carbohydrate or protein (4 kcal/g). Foods and beverages with a high fat content
Consumption of low-energy-dense preloads can enhance satiety
Satiety refers to the effects of food after eating has ended. To study satiety, a fixed amount of a defined food (a preload) is consumed; after an interval of time, the effect of the preload on subsequent test meal intake is measured. Satiety is also assessed by post-preload ratings of fullness using tools such as visual analog scales. The preloading paradigm has been used extensively to assess how foods and food components vary in their effects on satiety. Such studies have the potential to
Preload characteristics that can moderate the effect of energy density
In order to systematically investigate the mechanisms underlying the influence of energy density on satiety, we need a better understanding of how other properties of foods moderate the effect. The response to variations in preload volume by the addition of water has not been consistent. Several studies have failed to find that adding water to soup preloads influences satiety [7], [8]. Although negative findings are more difficult to interpret than those that are positive, one explanation that
Energy density and satiation: Effects on ad libitum energy intake
Energy density can influence energy intake not only by enhancing satiety, but also through effects on ad libitum intake. Ad libitum intake is an indicator of satiation, or the processes leading to the termination of eating during a meal. The study of satiation is challenging because even slight differences in the palatability of the test foods could obscure effects on intake related to variations in meal components. Until recently, most studies of satiation focused on the influence of the
Do characteristics of the individual affect satiation?
Most of our understanding of the effects of dietary energy density comes from studies in young to middle-aged adults. In these studies, no systematic relationship has been demonstrated between subject characteristics such as weight status, dietary restraint, and disinhibition and the response to variations in energy density. It is of particular interest to determine whether the effect of energy density is robust across different age groups, since it is thought that the control of energy intake
How does energy density affect satiation?
The effects of energy density are robust, affecting energy intake in children, adults of a wide range of ages, and individuals with different weight status and with various levels of concern about what they eat. When presented with different versions of foods that are similar in palatability, but vary in energy density, the typical response is to consume a consistent amount of food. This suggests that intake during a meal depends upon cognitive factors related to previous experiences with foods
Energy density and body weight
Another way to examine the persistence of any influence that dietary energy density has on energy intake is to determine whether the energy density of the diet is associated with body weight status. Some population-based studies have shown that normal-weight adults report consuming diets with a lower energy density than obese individuals [46]. Furthermore, dietary energy density was associated with the amount of weight gained over an eight-year period in a prospective study of over 50,000
Conclusion
In recent years dietary energy density has emerged as an important influence on energy intake; however, our understanding of how energy density affects satiety and satiation is limited. Studies that have been conducted indicate that these effects are complex and include both psychological and physiological mechanisms. Despite this complexity, dietary energy density needs to be explored further since it not only has robust effects on intake, but also can moderate the influence of other dietary
Acknowledgements
This research was supported by NIH grants R37DK039177 and R01DK059853, and by the Robert Wood Johnson Foundation.
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