Given the recent surge in obesity, effective dietary strategies for weight management are required. Because fruits and vegetables are high in water and fiber, incorporating them in the diet can reduce energy density, promote satiety, and decrease energy intake. Although few interventions have specifically addressed fruit and vegetable consumption, evidence suggests that coupling advice to increase intake of these foods with advice to decrease energy intake is a particularly effective strategy for weight management. This approach may facilitate weight loss because it emphasizes positive messages rather than negative, restrictive messages.

Reducing dietary energy density, particularly by combining increased fruit and vegetable intakes with decreased fat intake, is an effective strategy for managing body weight while controlling hunger.

The increase in the prevalence of obesity has coincided with an increase in portion sizes of foods both inside and outside the home, suggesting that larger portions may play a role in the obesity epidemic. Although it will be difficult to establish a causal relationship between increasing portion size and obesity, data indicate that portion size does influence energy intake. Several well-controlled, laboratory-based studies have shown that providing older children and adults with larger food portions can lead to significant increases in energy intake. This effect has been demonstrated for snacks and a variety of single meals and shown to persist over a 2-d period. Despite increases in intake, individuals presented with large portions generally do not report or respond to increased levels of fullness, suggesting that hunger and satiety signals are ignored or overridden. One strategy to address the effect of portion size is decreasing the energy density (kilojoules per gram; kilocalories per gram) of foods. Several studies have demonstrated that eating low-energy-dense foods (such as fruits, vegetables, and soups) maintains satiety while reducing energy intake. In a clinical trial, advising individuals to eat portions of low-energy-dense foods was a more successful weight loss strategy than fat reduction coupled with restriction of portion sizes. Eating satisfying portions of low-energy-dense foods can help to enhance satiety and control hunger while restricting energy intake for weight management.

The rise in obesity rates over the past 30 y has been paralleled by increases in the portion size of many foods and the prevalence of eating away from home. Foods of particular concern are those that have a high energy density (kJ/g). Many well-controlled, laboratory-based studies have found that large portions of energy-dense foods can lead to excess energy intakes. This influence of large portions on energy intake has been supported by data collected in naturalistic settings. Further research is needed to explore strategies that can be used to moderate the effects of portion size on food consumption. One promising strategy is to reduce the energy density of foods, while maintaining food weight or volume, so that consumers can eat satisfying portions while reducing their energy intakes. There is a need for effective educational messages that not only emphasize limiting the consumption of foods high in energy density, but also encourage the consumption of those with a low energy density, such as fruits and vegetables. The delivery of consistent messages will require more cooperation among the food and restaurant industries, policy makers, and scientists. Effective strategies will also require consumers to understand and accept the importance of eating reasonable portions for better health.

No abstract