Page 169 - Nutrition Essentials for Nursing Practice

C H A P T E R 7 Energy Balance 157
Protein
Fat Weig ht gain 0 Weightloss Thermic effect
of food
Carbohydrate
Physical
Calorie intake activity

Basal metabolic
rate

Calorie output

■ F I G U R E 7 . 1 Energy balance: calorie intake versus calorie output.

body weight are presented. Energy in health promotion focuses on the Dietary Guidelines
for Americans, 2010 (DGA) recommendations for weight management and physical activ-
ity (PA).

ENERGY INTAKE

Calories come from carbohydrates, protein, fat, and alcohol. The total number of calories
in a food or diet can be estimated by multiplying total grams of these nutrients by the
appropriate calories per gram—namely, 4 cal/g for carbohydrates and protein, 9 cal/g for
fat, and 7 cal/g for alcohol.

In practice, “counting calories” is an imprecise and painstaking process dependent on
knowing accurate portion sizes of all foods consumed and the exact nutritional composi-
tion of each item, neither of which conditions is easily met. Even when all food consumed
is measured, the nutrient values available in food composition references represent average
not actual nutrition content based on analysis of a number of food samples.

A less accurate but easier way to estimate calorie intake is to estimate or count the num-
ber of servings from each food group a person consumes. Multiply the number of servings
by the average amount of calories in a serving and then add the calories from each group
to get an approximation of the total calories consumed. Be aware that representative foods
within each of the Exchange Lists for Diabetics food groups are generally free of added fat
or sugar (Table 7.1). For instance, items like onion rings, brownies, and sugar-sweetened
cereals are not part of those food groups. As with “counting calories,” the accuracy of
“counting servings” depends on the quality of foods consumed and accuracy of portion
size estimation.

ENERGY EXPENDITURE

The body uses energy for involuntary activities and purposeful PA. The total of these expen-
ditures represents the number of calories a person uses in a day.