Page 170 - Nutrition Essentials for Nursing Practice

158 U N I T 1 Principles of Nutrition

Table 7.1 Calories by Food Groups

Food Group Representative Serving Size Average Calories per Serving

Starch/grains 1 oz bread 80
Fruits 1 medium piece 60
Milk 1 cup
100
Skim or 1% ½ cup 120
2% 1 oz 160
Whole
Nonstarchy vegetables 1 tsp butter 25
Protein foods
Plant-based protein Varies
Lean 45
Medium fat 75
High fat
Fat/oils 100
45

Source: American Diabetes Association, American Dietetic Association. (2008). Choose your foods: Exchange
lists for diabetes. Alexandria, VA: The American Diabetes Association.

Basal Metabolism

Basal Metabolic Rate Basal metabolism is the amount of calories required to fuel the involuntary activities of the
(BMR) or Basal body at rest after a 12-hour fast. These involuntary activities include maintaining body tem-
Energy Expenditure perature and muscle tone, producing and releasing secretions, propelling the gastrointestinal
(BEE): the amount of (GI) tract, inflating the lungs, and beating the heart. For most people, the basal metabolic
calories expended in a rate (BMR) or basal energy expenditure (BEE) accounts for approximately 60% to 70%
24-hour period to fuel of total calories expended. The less active a person is, the greater is the proportion of calo-
the involuntary activi- ries used for BEE. The term “BEE” is often used interchangeably with resting metabolic
ties of the body at rest rate (RMR) or resting energy expenditure (REE) even though they are slightly different
and after a 12-hour fast. measures.

Resting Metabolic One imprecise, rule-of-thumb guideline for estimating BMR is to multiply healthy
Rate (RMR) or weight (in pounds) by 10 for women and 11 for men. For example, a 130-pound woman
Resting Energy expends approximately 1300 cal/day on BMR (130 lb ϫ 10 cal/lb ϭ 1300 calories). When
Expenditure (REE): actual weight exceeds healthy weight, an “adjusted” weight of halfway between healthy
the amount of calories and actual can be used. For instance, if healthy weight is 130 lb, but actual weight is
expended in a 24-hour 170 lb, 150 lb would be the “adjusted” weight for estimating basal calories. Methods used
period to fuel the to determine BMR and total calorie requirements in the clinical setting are discussed in
involuntary activities of Chapter 16.
the body at rest. RMR
does not adhere to the A drawback of using a rule-of-thumb method for determining BMR is that it is based
criterion of a 12-hour only on weight; it does not account for other variables that affect metabolic rate, such as
fast, so it is slightly body composition. Lean tissue (muscle mass) contributes to a higher metabolic rate than fat
higher than BEE tissue. Therefore, people with more muscle mass have higher metabolic rates than do peo-
because it includes ple with proportionately more fat tissue. This explains why men, who have a greater pro-
energy spent on portion of muscle, have higher metabolic rates than women, who have a greater proportion
digesting, absorbing, of fat. Conversely, the loss of lean tissue that usually occurs with aging beginning sometime
and metabolizing food. around age 30 years is one reason why calorie requirements decrease as people get older.
However, strength training exercise can lead to significant gains in muscle strength and
size—and thus increase BMR—even among frail, institutionalized 90-year-old men and
women (Fiatarone et al., 1990). Other factors that affect BMR appear in Table 7.2.