Consumers interested in their nutrient and calorie intakes may be confused by discrepancies they see and hear with regard to what constitutes a serving size. The question can relate to the amount that should be eaten at a meal or over the course of a day. How are consumers to know the amounts that are appropriate for their needs?
Where some of the confusion arises is the amount of food provided by meals purchased outside the home. These tend to include quantities that are much larger than what is nutritionally and calorically appropriate for an individual.
On the nutrition panel of a food label, food manufacturers often note a serving size based on the amount normally eaten of a particular food. It is not always based on nutrient or caloric needs.
In contrast, the USDA MyPlate guidelines suggest goal amounts from each of the healthy food groups based on daily nutrient needs that are specified by age and calorie goals. They define specific quantities based upon certain forms of a food within a food group.
The diabetic exchange lists indicate serving sizes for items within each food group based on comparable calorie, carb, protein, and fat content. An example from the fruit group is substituting a medium-size apple for ½ cup of sliced strawberries. The carb and calorie content would be about the same based on these serving sizes. The exchange lists with their specified units of food are not only helpful for diabetics but also for others interested in nutrient and calorie-controlled eating plans.
The food group units indicated in the MyPlate Plan and the diabetic exchange lists are very similar to each other. Both can be used to plan food intake needs over a day’s time. Registered dietitians often create meal plans for individuals with these “units” or “serving sizes” in mind because they relate to nutrient needs and encourage a focus on a more nutrient dense eating.
If a consumer is concerned about body weight (either trying to increase or decrease weight), besides being attentive to nutritional needs, common sense still needs to be involved. Processed foods or foods purchased for use in a recipe can vary greatly in calorie content. For example, high fat deli meats will have a lot more calories than deli turkey even though they both fall under the protein food group.
Also keep in mind that a number of variables need to be considered when determining an individual’s nutrient and calorie needs – age, male vs female, body size, body weight goals, pregnancy, level and type of physical activity, certain medical conditions (such as diabetes, etc.), and other factors may influence food intake recommendations.
Information for specific units or serving sizes for the MyPlate or diabetic exchanges are available online, but let’s do a quick overview here. For fruit, a unit is a medium-sized piece of fruit, 4 oz. of 100% fruit juice, 2 Tbsp. dried fruit, ½ cup unsweetened canned fruit/applesauce/sliced fruit, or one cup of cut up cubes of fruit/whole berries.
For the non-starchy vegetables, a unit is ½ cup of raw or cooked, ½ cup tomato sauce or vegetable juice, or one cup of leafy greens. You can appropriately eat more of this group as it is full of great nutrients but low in calories.
A protein unit contains about 6-8gm of protein. This would be mean one ounce of meat/poultry/seafood, one egg or two egg whites, ½ cup of beans/lentils, 2 Tbsp. nut or seed butter, ¼ cup of nuts/seeds, or the amount of a soy product (edamame, tofu, etc.) comparable to a protein unit.
A grain unit has about 15gm of carbs which would be about one half cup of cooked grain (such as brown rice, whole grain pasta, quinoa, farro, etc.), ½ cup of a starchy vegetable (corn, potato, sweet potato, etc.), ½ cup of cooked cereal, ½ cup of beans/lentils, two cups of popped popcorn, or about one thinner slice of bread.
To determine how many grain units are contained in other grain foods, just divide the carbs noted as a serving on the label by 15. For example, a large tortilla (noted as one serving on the food label) containing 45gm of carbs would actually count as three grain units. This tip cannot be used for foods containing other sources of carbs such as fruit or added sugars, as in some dry cereals.
So let’s look at a basic diet for an adult doing moderate amounts of physical activity. Based on units/servings noted in the MyPlate Plan or the diabetic exchange lists, general daily goals might be – three fruit, four or more vegetables, six to seven units of protein, five to six of grains, and three to five units of dairy or comparable calcium sources.
The goal for protein units is based upon some protein coming from dairy sources of calcium. If an individual is not using dairy or soymilk as sources of calcium, then the number of units for protein would need to be a bit higher (note that alternative milks tend to be low in protein).
Assuming healthier versions of foods within these groups are consumed, these numbers could support an individual at a healthy body weight. For persons currently eating more than these amounts or for those choosing more calorie-dense foods, this baseline could provide for weight loss and still support nutritional needs.
As noted above, nutrient and calorie needs are dependent upon a number of variables, so check out more detailed goals on the MyPlate Plan, American Diabetes Association, and Dietary Guidelines for Americans web sites, and consider guidance from a registered dietitian to personalize your goals.
Pam Stuppy, MS, RD, LD is a registered, licensed dietitian with nutrition counseling offices in York, ME and Portsmouth, NH. She has also been the nutritionist for Phillips Exeter Academy, presents workshops nationally, and provides guidance in sports nutrition. (See www.pamstuppynutrition.com for more nutrition information, some healthy cooking tips, and recipe ideas).