Kyla and Garrett are 25 years old and have been married 6 months. Since then, she has gained 10 to 15 pounds and he has gained 40 pounds, which they attribute to eating dinner out three to four times a week and getting takeout the other days of the week. They are shocked at how quickly “things got out of control” and want to adopt a healthier lifestyle before embarking on parenthood.
Check Your Knowledge
True
False
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1
A food that is high in “energy” is high in calories.
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□
2
A pound of body fat is equivalent to 3500 calories.
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3
People shaped like “apples” are at greater health risk than people shaped like “pears.”
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□
4
The formulas to calculate body mass index (BMI) are different for men and women.
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□
5
Calorie-dense foods provide a relatively high amount of calories with low levels of vitamins, minerals, and other beneficial substances.
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□
6
The majority of calories expended daily by most Americans are spent on basal needs.
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7
Building muscle increases metabolic rate.
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8
To reap health benefits, you must participate in continuous activity for at least 30 minutes.
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9
Sitting too much may be a health risk even when physical activity goals are met.
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10
An effective strategy for limiting calorie intake is to limit food and beverages high in added sugar and solid fat.
Learning Objectives
Upon completion of this chapter, you will be able to
1 Estimate an individual’s total calorie requirements.
2 Determine an individual’s BMI.
3 Evaluate weight status based on BMI.
4 Assess a person’s waist circumference.
5 Compare the terms “nutrient density” and “calorie density.”
6 Evaluate a person’s usual activity level based on Dietary Guidelines recommendations.
Figure 7.1 ▲ A state of energy balance: Calorie intake is equal to calorie output.
The state of energy balance is the relationship between the amount of energy (calories) consumed and the amount of energy (calories) expended. When calorie intake and output are balanced—that is, approximately the same over time—body weight is stable (Fig. 7.1). A positive energy balance occurs when calorie intake exceeds calorie output, whether the imbalance is caused by overeating, low activity, or both (Fig. 7.2). Over time, the calories consumed in excess of need contribute to weight gain. Because a pound of body fat is equivalent to 3500 calories, a surplus of 500 cal/day over a 7-day period can result in a 1-pound weight gain. Conversely, a negative calorie balance occurs when calorie output exceeds intake, whether the imbalance is from decreasing calorie intake, increasing PA, or (preferably) both (Fig. 7.3).
This chapter discusses energy intake, energy output, and how total calorie requirements are estimated. Methods of evaluating body weight are presented. Energy in health promotion focuses on the 2015-2020 Dietary Guidelines for Americans recommendations for weight management and physical activity.
Figure 7.2 ▲ A positive energy balance: Calorie intake is greater than calorie output.
Figure 7.3 ▲ A negative energy balance: Calorie intake is less than calorie output.
ENERGY INTAKE
Technically, a calorie is the amount of energy required to raise the temperature of 1 kg of water by 1°C. In nutrition, calories are the measure of the amount of energy in a food or used by the body to fuel activity. Energy balance is a function of calorie intake versus calorie output (Fig. 7.4).
Calorie unit by which energy is measured; the amount of heat needed to raise the temperature of 1 kg of water by 1°C. Technically, calorie is actually kilocalorie or kcal.
Carbohydrates, protein, fat, and alcohol provide calories. The total number of calories in a food or eating pattern 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”—whether manually, online, or with a mobile phone app—is an imprecise process dependent on knowing accurate portion sizes of all foods consumed and the exact nutritional composition of each item, neither of which conditions is easily met. Even when all food consumed is measured, the nutrient values available in food composition databases represent average not actual nutrition content based on analysis of a number of food samples.
An imprecise but easy way to estimate calorie intake is to estimate or count the number of servings from each food group a person consumes. Using a standard reference, such as Food Lists for Weight Management (American Diabetes Association & Academy of Nutrition and Dietetics, 2014), the number of servings from each group is multiplied by the average amount of calories in a serving (Table 7.1). The sum of from all food groups provides an approximation of total calories consumed. However, representative foods within each of the Food Lists groups are generally free of added fat or sugar. For instance, items such as onion rings, cheesecake, and sugar-sweetened beverages are not part of those food groups. It is easy to underestimate calorie intake if the actual foods consumed are higher in caloric density.
Figure 7.4 ▲ Sources of calorie intake and calorie expenditure.
Table 7.1 Calories by Food Lists
Food Group
Representative Serving Size
Average Calories per Serving
Starch (breads, grains, cereals, starchy vegetables, dried peas and beans)
1 oz bread
80
Fruits
1 small fresh fruit, 1/2 cup canned or frozen fruit
The drawback of counting calories by any method is that appropriate calories are only one aspect of a healthy eating pattern; nutritional adequacy is not guaranteed. For instance, an individual can eat the appropriate number of calories, but if the calories come from burgers and fries and not fruits, vegetables, whole grains, or dairy, the pattern is not healthy even though it is calorie appropriate.
Unfolding Case
Recall Kyla and Garrett. A food record would help identify the types, amounts, and pattern of food they eat so that a strategy to improve intake can be formulated. What other factors need to be assessed before recommending changes to their intake?
ENERGY EXPENDITURE
The body uses energy for involuntary activities and purposeful PA. The thermic effect of food is another category of energy expenditure, although in practice it is often disregarded. The total of these expenditures represents an estimate of the number of calories a person expends in a day (Box 7.1).
Basal Metabolism
Basal metabolism is the amount of calories required to fuel the involuntary activities of the body at rest after a 12-hour fast. These involuntary activities include maintaining body temperature and muscle tone, producing and releasing secretions, propelling the gastrointestinal tract, inflating the lungs, and beating the heart. For most people, the basal metabolic rate (BMR) or basal energy expenditure (BEE) accounts for approximately 60% to 70% of total calories expended. The less active a person is, the greater is the proportion of calories used for BEE. The term “BEE” is often used interchangeably with resting metabolic rate (RMR) or resting energy expenditure (REE) even though they are slightly different measures.
Basal Metabolic Rate (BMR) or Basal Energy Expenditure (BEE) the amount of calories expended in a 24-hour period to fuel the involuntary activities of the body at rest and after a 12-hour fast.
Resting Metabolic Rate (RMR) or Resting Energy Expenditure (REE) the amount of calories expended in a 24-hour period to fuel the involuntary activities of the body at rest. RMR does not adhere to the criterion of a 12-hour fast, so it is slightly higher than BEE because it includes energy spent on digesting, absorbing, and metabolizing food.
One imprecise, rule-of-thumb guideline for estimating BMR is to multiply healthy weight (in pounds) by 10 for women and 11 for men. For example, a 130-pound woman expends approximately 1300 cal/day on BMR (130 pounds × 10 cal/pound = 1300 calories). When actual weight exceeds healthy weight, an “adjusted” weight of halfway between healthy and actual can be used. For instance, if healthy weight is 130 pounds, but actual weight is 170 pounds, 150 pounds would be the “adjusted” weight for estimating basal calories. Methods used to determine BMR and total calorie requirements in the clinical setting are discussed in Chapter 16.
A drawback of using a rule-of-thumb method for determining BMR is that it is based only on weight; it does not account for other variables that affect metabolic rate, such as body composition. Lean tissue (muscle mass) contributes to a higher metabolic rate than fat tissue. Therefore, people with more muscle mass have higher metabolic rates than do people with proportionately more fat tissue. This explains why men, who have a greater proportion of muscle, have higher metabolic rates than women, who have a greater proportion of fat. Conversely, the loss of lean tissue that usually occurs with aging is one reason why calorie requirements decrease as people get older. Other factors that affect BMR appear in Table 7.2.
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.
_____ (weight in pounds) × _____ = __________ 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.
_____ (calories for BMR) × _____ % = calories spent on activity
Sedentary: mostly sitting, driving, sleeping, standing, reading, typing, and other low-intensity activities
20
Light activity: light exercise such as walking not more than 2 hours/day
30
Moderate activity: moderate exercise such as heavy housework, gardening, and very little sitting
40
High activity: active in physical sports or a labor-intensive occupation such as construction work
50
3. Add BMR calories and physical activity calories
________ calories for BMR + ________ calories spent on activity = ________ estimate of total expended daily (imprecise estimate of thermic effect of food is generally not included).
Table 7.2 Factors that Affect Basal Metabolic Rate (BMR)
Variables
Effect on Metabolism
Age
Loss of lean body mass with age lowers BMR.
Growth
The formation of new tissue, as seen in children and during pregnancy, increases BMR.
Stresses
Stresses, such as infection and many diseases, raise BMR.
Thyroid hormones: tetraiodothyronine (thyroxine, or T4) and triiodothyronine (T3)
An oversecretion of thyroid hormones (hyperthyroidism) speeds up BMR; undersecretion of thyroid hormones (hypothyroidism) lowers BMR. The change may be as great as 50%.
Fever
BMR increases 7% for each degree Fahrenheit above 98.6.
Height
When considering two people of the same gender who weigh the same, the taller one has a higher BMR than the shorter one because of a larger surface area.
Extreme environmental temperatures
Very hot and very cold environmental temperatures increase the BMR because the body expends more energy to regulate its own temperature.
Starvation, fasting, and malnutrition
Part of the decline in BMR that occurs with these conditions is attributed to the loss of lean body tissue. Hormonal changes may contribute to the decrease in metabolic rate.
Weight loss from calorie deficits
With smaller body mass, less energy is required to fuel metabolism.
Smoking
Nicotine increases BMR.
Caffeine
Increases BMR
Certain drugs, such as barbiturates, narcotics, and muscle relaxants
Decrease BMR
Sleep, paralysis
Decrease BMR
Physical Activity
Physical activity (PA), or voluntary muscular activity, generally accounts for approximately 30% of total calories used, although it may be as low as 20% in sedentary people and as high as 50% in people who are very active. The actual amount of energy expended on PA depends on the intensity and duration of the activity and the weight of the person performing the activity. The more intense and longer the activity, the greater is the amount of calories burned. Heavier people, who have more weight to move, use more energy than lighter people to perform the same activity. A rule-of-thumb method for estimating daily calories expended on PA is to calculate the percentage increase above BMR on the basis of estimated intensity of usual daily activities (Box 7.1). Estimating calorie expenditure from PA is easily obtained by wearing a device created to track activity and other functions, such as sleep, heart rate, calorie intake, and calorie output. Using algorithms and sensors, such as temperature sensors and optical sensors, trackers measure motion which is then converted into steps and activity; from there, calories and sleep quality are estimated. Apps present the data after more fine-tuning with algorithms. Due to differences in sensors and algorithms, reported statistics vary among individual devices even when the same data is used. Mobile phones have similar built-in sensors that pedometer-like apps can use to estimate activity. Tracking devices provide an estimate, not an actual reading.
Thermic Effect of Food
The thermic effect of food is another category of energy expenditure that represents the calories spent on processing food. In a normal mixed diet, the thermal effect of food is estimated to be about 10% of the total calorie intake. For instance, people who consume 1800 cal/day use about 180 calories to process their food. The actual number of calories spent varies with the composition of food eaten, the frequency of eating, and the size of meals consumed. Although it represents an actual and legitimate use of calories, the thermic effect of food in practice is often disregarded when calorie requirements are estimated because it constitutes such a small amount of energy and is imprecisely estimated.
Thermic Effect of Food an estimation of the amount of energy required to digest, absorb, transport, metabolize, and store nutrients.
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 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.
Unfolding Case
Think of Kyla and Garrett. They want to lose weight and they also want to eat healthy. Often, people forget about health and just concentrate on calories and weight. Although their estimated calories as sedentary 25-year-olds are 2000 calories for Kyla and 2400 calories for Garrett, they do not want to count calories or measure serving sizes. What strategies can they use to eat a healthy, calorie-appropriate eating pattern that will promote weight loss without actually counting calories?
EVALUATING WEIGHT STATUS
From a health perspective, healthy or desirable weight is that which is statistically correlated to good health. But the relationship between body weight and good health is more complicated than simply the number on the scale. For instance, although increased body weight is a risk factor for type 2 diabetes, actual risk is more accurately related to the quantity and distribution of body fat (Després, 2012). However, methods to accurately assess quantity of body fat and its distribution are not readily available or cost-effective (Hsu, Araneta, Kanaya, Chiang, & Fujimoto, 2015). Therefore, the most widely used tool to assess risk for obesity-related diseases is to evaluate weight for height because it is economical and practical in clinical settings and epidemiological studies (Hsu et al., 2015).
Body Mass Index
Ideal Body Weight the formula given here is a universally used standard in clinical practice to quickly estimate a person’s reasonable weight based on height, even though this and all other methods are not absolute.
Historically, a quick and easy method of calculating ideal body weight and evaluating weight for height is the Hamwi method (Table 7.4). However, since the early 1980s, weight status has been assessed by body mass index (BMI). BMI is calculated by dividing weight in kilograms by height in meters squared (kg/m2). Nomograms and tables that plot height and weight to determine BMI eliminate complicated mathematical calculations (Table 7.5). Established cutoffs identify overweight as BMI ≥25 and obese as BMI ≥30, which are based on the rationale that adults with a BMI ≥25 have increased risks of both morbidity and mortality (National Institutes of Health, 1998). Those risks include coronary heart disease, hypertension, hypercholesterolemia, type 2 diabetes, and other diseases.
Table 7.3 Estimated Calorie Needs per Day by Age, Gender, and Physical Activity Level
Estimated amounts of calories*** needed to maintain calorie balance for various gender and age groups at three different levels of physical activity. The estimates are rounded to the nearest 200 calories for assignment to a USDA Food Pattern. An individual’s calorie needs may be higher or lower than these average estimates.
* Estimates for females do not include women who are pregnant or breastfeeding.
** Sedentary means a lifestyle that includes only the light physical activity associated with typical day-to-day life. Moderately active means a lifestyle that includes physical activity equivalent to walking about 1.5 to 3 miles per day at 3 to 4 miles per hour, in addition to the light physical activity associated with typical day-to-day life. Active means a lifestyle that includes physical activity equivalent to walking more than 3 miles per day at 3 to 4 miles per hour, in addition to the light physical activity associated with typical day-to-day life.
*** Based on estimated energy requirements (EER) equations, using reference heights (average) and reference weights (healthy) for each age-gender group. For children and adolescents, reference height and weight vary. For adults, the reference man is 5 ft 10 in tall and weighs 154 pounds. The reference woman is 5 ft 4 in tall and weighs 126 pounds. EER equations are from the Institute of Medicine. (2002). Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. Washington, DC: The National Academies Press.
Percentage of “ideal” body weight as determined by the Hamwi method (% IBW)
Hamwi method calculation
Women: Allow 100 pounds for the first 5 ft of height; add 5 pounds for each additional inch.
Men: Allow 106 pounds for the first 5 ft of height: add 6 pounds for each additional inch
≤69% severe malnutrition
70%-79% moderate malnutrition
80%-89% mild malnutrition
90%-110% within normal range
110%-119% overweight
≥120% obese
≥200% morbidly obese
Body mass index (BMI)
For men and women: weight in kg ÷ height in meters squared
≤18.5 may ↑ health risk
18.5-24.9 healthy weight
25-29.9 overweight
30-34.9 obesity class 1
35-39.9 obesity class 2
≥ 40 obesity class 3
Table 7.5 Body Mass Index
Normal
Overweight
Obese
Extreme Obesity
BMI
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
Height (inches)
Body Weight (pounds)
Body Weight (pounds)
58
91
96
100
105
110
115
119
124
129
134
138
143
148
153
158
162
167
172
177
181
186
191
196
201
205
210
215
220
224
229
234
239
244
248
253
258
59
94
99
104
109
114
119
124
128
133
138
143
148
153
158
163
168
173
178
183
188
193
198
203
208
212
217
222
227
232
237
242
247
252
257
262
267
60
97
102
107
112
118
123
128
133
138
143
148
153
158
163
168
174
179
184
189
194
199
204
209
215
220
225
230
235
240
245
250
255
261
266
271
276
61
100
106
111
116
122
127
132
137
143
148
153
158
164
169
174
180
185
190
195
201
206
211
217
222
227
232
238
243
248
254
259
264
269
275
280
285
62
104
109
115
120
126
131
136
142
147
153
158
164
169
175
180
186
191
196
202
207
213
218
224
229
235
240
246
251
256
262
267
273
278
284
289
295
63
107
113
118
124
130
135
141
146
152
158
163
169
175
180
186
191
197
203
208
214
220
225
231
237
242
248
254
259
265
270
278
282
287
293
299
304
64
110
116
122
128
134
140
145
151
157
163
169
174
180
186
192
197
204
209
215
221
227
232
238
244
250
256
262
267
273
279
285
291
296
302
308
314
65
114
120
126
132
138
144
150
156
162
168
174
180
186
192
198
204
210
216
222
228
234
240
246
252
258
264
270
276
282
288
294
300
306
312
318
324
66
118
124
130
136
142
148
155
161
167
173
179
186
192
198
204
210
216
223
229
235
241
247
253
260
266
272
278
284
291
297
303
309
315
322
328
334
67
121
127
134
140
146
153
159
166
172
178
185
191
198
204
211
217
223
230
236
242
249
255
261
268
274
280
287
293
299
306
312
319
325
331
338
344
68
125
131
138
144
151
158
164
171
177
184
190
197
203
210
216
223
230
236
243
249
256
262
269
276
282
289
295
302
308
315
322
328
335
341
348
354
69
128
135
142
149
155
162
169
176
182
189
196
203
209
216
223
230
236
243
250
257
263
270
277
284
291
297
304
311
318
324
331
338
345
351
358
365
70
132
139
146
153
160
167
174
181
188
195
202
209
216
222
229
236
243
250
257
264
271
278
285
292
299
306
313
320
327
334
341
348
355
362
369
376
71
136
143
150
157
165
172
179
186
193
200
208
215
222
229
236
243
250
257
265
272
279
286
293
301
308
315
322
329
338
343
351
358
365
372
379
386
72
140
147
154
162
169
177
184
191
199
206
213
221
228
235
242
250
258
265
272
279
287
294
302
309
316
324
331
338
346
353
361
368
375
383
390
397
73
144
151
159
166
174
182
189
197
204
212
219
227
235
242
250
257
265
272
280
288
295
302
310
318
325
333
340
348
355
363
371
378
386
393
401
408
74
148
155
163
171
179
186
194
202
210
218
225
233
241
249
256
264
272
280
287
295
303
311
319
326
334
342
350
358
365
373
381
389
396
404
412
420
75
152
160
168
176
184
192
200
208
216
224
232
240
248
256
264
272
279
287
295
303
311
319
327
335
343
351
359
367
375
383
391
399
407
415
423
431
76
156
164
172
180
189
197
205
213
221
230
238
246
254
263
271
279
287
295
304
312
320
328
336
344
353
361
369
377
385
394
402
410
418
426
435
443
Source: Adapted from U.S. Department of Health and Human Services. (1998). Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: The evidence report. Rockville, MD: Author.
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