Page 172 - Nutrition Essentials for Nursing Practice

160 U N I T 1 Principles of Nutrition

Thermic Effect of Food

Thermic Effect of The thermic effect of food is another category of energy expenditure that represents the
Food: an estimation of “cost” of processing food. In a normal mixed diet, it is estimated to be about 10% of the
the amount of energy total calorie intake. For instance, people who consume 1800 cal/day use about 180 calories
required to digest, to process their food. The actual thermic effect of food varies with the composition of food
absorb, transport, eaten, the frequency of eating, and the size of meals consumed. Although it represents an
metabolize, and store actual and legitimate use of calories, the thermic effect of food in practice is often disre-
nutrients. garded when calorie requirements are estimated because it constitutes such a small amount
of energy and is imprecisely estimated.

Estimating Total Energy Expenditure

Total calorie needs can be imprecisely estimated by using predictive equations, of which
more than 200 have been published. The following are different approaches for estimating
calorie needs; all yield estimates, not precise measurements.

■ Add the results of the rule-of-thumb methods described earlier for estimating BMR and
calories spent on activity (Box 7.1).

■ Use a simple formula of calories per kilogram of body weight, such as 25 cal/kg to
30 cal/kg, which is often used for nonobese adults. This formula is adjusted upward or
downward based on the client’s age, weight, or activity level.

■ Use a standard reference that lists estimated daily calorie needs based on gender, age, and
activity. Table 7.3 lists estimated daily calorie needs.

Box 7.1 ESTIMATING TOTAL ENERGY EXPENDITURE

1. Estimate basal metabolic rate (BMR)

Multiply your healthy weight (in pounds) by 10 for women or 11 for men. If you
are overweight, multiply by the average weight within your healthy weight range
(see Chapter 14).

_____ (weight in pounds) ϫ _____ ϭ __________ calories for BMR

2. Estimate total calories according to usual activity level

Choose the category that describes your usual activities and then multiply BMR by
the appropriate percentage.

Sedentary: mostly sitting, driving, sleeping, standing, 20
reading, typing, and other low-intensity activities 30
40
Light activity: light exercise such as walking not 50
more than 2 hours/day

Moderate activity: moderate exercise such as heavy
housework, gardening, and very little sitting

High activity: active in physical sports or a labor-
intensive occupation such as construction work

3. Add BMR calories and physical activity calories

_______ calories for BMR ϩ ________ calories spent on activity ϭ ________ calories
spent on involuntary and physical activity

4. Add estimate of thermic effect of food

_______ calories spent on involuntary and voluntary activity ϩ 10% for processing
food ϭ ________ total calories expended daily