Researchers recruited 100 adults into a study on how adjusting portion sizes of vegetables at meals can be used to increase vegetable intake. Approximately half the adults were served a test meal in which vegetables were provided in addition to standard servings of grain and meat. The other half of the group ate vegetables in place of some of the grain and meat servings.
In the addition study, equal amounts of the grain and meat were served in all test meals. As the portion of the vegetable was increased, the total volume and calorie content of food served at the meal increased as well.
In the substitution study, as the vegetable portions were increased, the amount of the grain and meat were decreased. The total volume of food served at each meal did not change. The total calories served at the meal did decrease, because vegetables are less caloric than grains and meats.
In both the addition and substitution studies, an increase in the vegetable portion size resulted in greater vegetable consumption during the meal. Adding vegetables did not affect the number of calories consumed at the meal. However, substituting vegetables for grains and meat decreased the calories consumed at the meal. Substituting the most vegetables decreased the calorie content of the meal by about 15%.
This study discovered two important things. First, simply adding a larger serving of vegetables to a meal is a good way to help people eat more of these healthful foods. Second, replacing higher-calorie parts of a meal with vegetables will increase vegetable intake and decrease calorie intake.
In order to improve your diet, go with whichever strategy will help you meet your goals. Nearly all of us need to eat more veggies, but not everyone is concerned about their weight. If your main goal is to eat more vegetables, increase your portion sizes of these foods every chance you get.
If you are among the two-thirds of Americans who could benefit from eating more vegetables and shedding a few pounds, shift the portions on your plate so that one-half to two-thirds of every meal comes from vegetables. Replacing some of your usual meal staples with vegetables is a win-win for anyone seeking easy ways to cut a few calories!
(Am J Clin Nutr 2010; 91:913–22)