N° 9 | February 2007

The importance of Energy Density in Weight Management

Common strategies to reduce energy intake include limiting portion sizes, food groups, or certain macronutrients such as carbohydrates or fats. These strategies can help moderate calorie intake, particularly during the short-term; but they do have limitations. These approaches may compromise diet quality or cause feelings of hunger and dissatisfaction, which can limit their acceptability, sustainability, and long-term effectiveness. An alternative strategy for managing calorie intake is to encourage people to eat more foods that are low in calories for a given measure— that is, are low in energy density (kcal/g).

What is energy density?

Energy density is the amount of energy or calories in a particular weight of food (i.e., kcal/g). Foods with a lower energy density provide fewer calories per gram than foods with a higher energy density. For the same amount of calories, a person can consume a larger portion of a lowerenergy-dense food than a food higher in energy density.

Foods with a lower energy density, such as fruits, vegetables, and brothbased soups; tend to have a high water content, lots of fiber, or little fat. Water, which has an energy density of 0 kcal/g, lowers the energy density of foods as it contributes weight but not energy to foods. Fiber also has a relatively low energy density (1.5–2.5 kcal/g). Fat, however, is the most energy dense component of food (9 kcal/g), providing more than twice as many calories as protein or carbohydrates (4 kcal/g). While most high-fat foods have a high energy density, increasing the water content lowers the energy density of all foods, even those high in fat. For example, adding water-rich vegetables to casseroles lowers the energy density of these dishes.

Low-energy-dense diets, energy intake and satiety

Observational studies have shown people who report eating a lowerenergy-dense diet have a lower energy intake yet consume more food by weight than people who eat a higher energy dense diet(1-3). Experimental studies confirm that consuming foods lower in energy density is an effective strategy for reducing calorie intake and show that calorie intake can be reduced without increasing feelings of hunger. In one of these studies participants were given a standard lunch on different occasions preceded each time with either a first-course salad of differing energy density or by no salad(4). Participants consumed fewer calories when the meal started with the lower-energy-dense salad and they reported feeling just as full as participants who had no first-course salad or had a salad that was higher in energy density.

Multiple longer-term studies have found that over the course of a few days, people generally consume a fairly consistent amount of food. Therefore, calorie intake is lower when people eat foods low in energy density(5-10). Encouraging people to eat more foods low in energy density and to substitute these foods for those higher in energy density helps them decrease their caloric intake while eating satisfying portions of food and controlling hunger.

Low-energy-dense diets and body weight

Several observational studies suggest that a relationship exists between consuming an energy dense diet and obesity(1, 11-13). For example, normal weight adults have been shown to consume diets lower in energy density than obese individuals(1). Additional evidence supporting the use of diets rich in low-energy-dense foods for weight-loss comes from clinical interventions.

Rolls and colleagues(14) examined the effectiveness of incorporating either a low-energy-dense food or a high-energy-dense food into a reducedenergy diet. During this year long trial overweight and obese men and women were provided with one of the following items to incorporate into their daily diet: one serving of soup, two servings of soup, two servings of a dry snack food, or no special food. The researchers found that weight loss was significantly correlated with the overall decrease in the energy density of the diet. Participants consuming two servings per day of lowenergy-dense soup experienced 50% greater weight loss than participants who consumed two servings per day of high-energy-dense dry snacks (7.2 kg vs. 4.8 kg).

In another year-long trial, Ello-Martin and colleagues(15) tested two strategies to reduce the energy density of the diet without providing the subjects with specific calorie limits. One group of obese women was advised to decrease the energy density of their diets by increasing consumption of fruits and vegetables and choosing reduced-fat foods. Another group was counseled only on reducing fat intakes. The group counseled to eat more fruits and vegetables while also reducing fat intake experienced a greater reduction in the energy density of their diets and lost 23% more weight (7.9 kg vs. 6.4 kg). Furthermore, these participants reported consuming more food and experiencing less hunger.

These studies suggest that dietary advice to reduce the energy density of the diet is an effective strategy for weight loss. A benefit of this type of eating plan is that it allows people to eat satisfying amounts of food while restricting their energy intake. Furthermore, it uses positive messages (i.e., eat satisfying portions of low-energy-dense foods) and results in a nutritionally sound eating pattern(16).

  1. Ledikwe JH, Blanck HM, Kettel Khan L, et al. Dietary energy density is associated with energy intake and weight status in US adults. Am J Clin Nutr 2006;83:1362-8.
  2. Cuco G, Arija V, Marti-Henneberg C, Fernandez-Ballart J. Food and nutritional profile of high energy density consumers in an adult Mediterranean population. European Journal of Clinical Nutrition 2001;55:192-9.
  3. Drewnowski A, Almiron-Roig E, Marmonier C, Lluch A. Dietary energy density and body weight: is there a relationship? Nutrition Reviews 2004;62:403-413.
  4. Rolls BJ, Roe LS, Meengs JS. Salad and satiety: energy density and portion size of a first course salad affect energy intake at lunch. Journal of the American Dietetic Association 2004;104:1570-1576.
  5. Bell EA, Castellanos VH, Pelkman CL, Thorwart ML, Rolls BJ. Energy density of foods affects energy intake in normal-weight women. American Journal of Clinical
    Nutrition 1998;67:412-420.
  6. Duncan KH, Bacon JA, Weinsier RL. The effects of high and low energy density diets on satiety, energy intake, and eating time of obese and nonobese subjects.
    American Journal of Clinical Nutrition 1983;37:763-767.
  7. Shintani TT, Hughes CK, Beckham S, O’Connor HK. Obesity and cardiovascular risk intervention through the ad libitum feeding of traditional Hawaiian diet. American Journal of Clinical Nutrition 1991;53:1647S-1651S.
  8. Lissner L, Levitsky DA, Strupp BJ, Kalkwarf HJ, Roe DA. Dietary fat and the regula tion of energy intake in human subjects. American Journal of Clinical Nutrition
  9. Kendall A, Levitsky DA, Strupp BJ, Lissner L. Weight loss on a low-fat diet: consequence of the imprecision of the control of food intake in humans. American
    Journal of Clinical Nutrition 1991;53:1124-1129.
  10. Rolls BJ, Bell EA, Castellanos VH, Chow M, Pelkman CL, Thorwart ML. Energy density but not fat content of foods affected energy intake in lean and obese
    women. American Journal of Clinical Nutrition 1999;69:863-871.
  11. Marti-Henneberg C, Capdevila F, Arija V, et al. Energy density of the diet, food volume and energy intake by age and sex in a healthy population. European
    Journal of Clinical Nutrition 1999;53:421-8.
  12. Cox DN, Mela DJ. Determination of energy density of freely selected diets: methodological issues and implications. International Journal of Obesity and Related
    Metabolic Disorders 2000;24:49-54.
  13. Kant AK, Graubard BI. Energy density of diets reported by American adults: association with food group intake, nutrient intake, and body weight. Int J Obes (Lond) 2005;29:950-6.
  14. Rolls BJ, Roe LS, Beach AM, Kris-Etherton PM. Provision of foods differing in energy density affects long-term weight loss. Obesity Research 2005;13:1052-1060.
  15. Ello-Martin JA, Roe LS, Rolls BJ. A diet reduced in energy density results in greater weight loss than a diet reduced in fat. Obesity Research 2004;12:A23.
  16. Ello-Martin JA, Roe LS, Ledikwe JH, Beach AM, Rolls BJ. Dietary energy density in the treatment of obesity: a year-long trial comparing two weight-loss diets. submitted.
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