Deck 18: Body Composition and Nutrition for Health

Question 1

What is the principle of underwater weighing Why should a different body density equation be used for children, in contrast to adults

Answer 1

Underwater weighing of body mass is used to estimate body composition in two component system. Density of a body equals its mass divided by volume. Body mass (weight) is measured directly, and body volume is to be determined to calculate density. The body volume is determined used Archimedes principle. According to this principle, when an object is placed in water, it displaces water to be buoyed up, by a counterforce. The volume of displaced water is equal to the volume of the body.
However, some scientists obtain body volume by subtracting the weight measured in water (MW) from that measure in air (MA). The more accurate formula to convert the weight of water displaced to a volume is as follows:
Where D = density
M = mass of the body
V = volume of the body
M A = weight measured in air
M W = weight measured under water
D W = density of the water
The categorization of whole body density values to fat and fat free tissue components depends on the constants used to measure each of these tissue components. The measurement is based on the fact that fat is less dense than water with a density of 0.90 g/ml, whereas fat-free tissue has a density of 1.10 g/ml.
Percent fat for a subject is calculated using the following formula:
The disadvantages of this method are that density of fat varies among populations, and bone mineral content is less in children due to which their bone density is lower compared to adults. Similarly, elders have less bone density compared to young adults. Therefore, the chance of standard deviation is high in this method of body mass estimation. To correct this, a different equation is used for children to estimate body fat, as given below:

Question 2

Given: a 20-year-old college male, 180 lb, 28% fat. What is his target body weight to achieve 17% fat

Answer 2

The information of % fat can be used to estimate one's health status relative to fitness. The body weight that is associated with a specific fitness standard can be measured by calculating the fat-free weight of the body and then calculating the goal weight.
The following is the information provided:
Age of the subject = 20 years
Weight of the subject = 180 lb
Fat composition = 28%
Target fat composition = 17%
Step 1: The fat-free weight is calculated:
Given that fat composition iS₂8%, fat free mass composition is 100 - 28 = 72%
The fat free body weight =
Step 2: Goal % fat is expressed as fraction, and the target body weight to achieve the goal % fat is calculated using the following formula:
Therefore, the target body weight to achieve 17% fat is

Question 3

In terms of the resistance to weight reduction, contrast obesity due to hypertrophy with obesity due to hyperplasia of fat cells.

Answer 3

Hypertrophic obesity is due to an increase in the amount of fat in each fat cell, whereas hyperplastic obesity is due to an increase in the number of fat cells. Hypertrophic obesity is mainly responsible for moderate obesity where the mass of adipose tissue is less than 30 kg. Beyond that limit, the cell number that stores fat increases. The fat cell number is strongly related to the mass of adipose tissue.
With exercise, persons with hyperplastic obesity or combined hyperplastic and hypertrophic obesity lose weight quickly. Those who have hypertrophic obesity have difficulty in reducing body weight, since the number of fat cells does not change with exercise or dieting. The cells only reduce in size, and if exercise is not done regularly, fat is regained at a high rate.

Question 4

Is obesity more related to genetics or the environment

Question 5

If a person consumes 120 kcal per day in excess of need, what weight gain does the static energy balance equation predict compared to the dynamic energy balance equation

Question 6

What does nutrient balance mean and how is the ratio of the RQ to FQ used to determine nutrient balance

Question 7

Contrast a physiological set point with a behavioral set point related to obesity.

Question 8

What happens to the BMR when a person goes on a low-calorie diet

Question 9

Summarize the range of carbohydrate, fat, and protein intakes recommended by the Institute of Medicine.

Question 10

What recommendations would you give about the use of diet alone versus a combination of diet and exercise to achieve a weight-loss goal

Question 11

What is the difference between an RDA standard and a Daily Value

Question 12

What is thermogenesis and how might it be related to a weight gain

Question 13

Is there any risk in taking fat-soluble vitamins in large quantities Explain.

Question 14

What is the effect of exercise on appetite and body composition

Question 15

Which two minerals are believed to be inadequate in women's diets

Question 16

In contrast to the general physical activity recommendation for achieving significant health benefits, how much physical activity may be needed to prevent weight gain or maintain weight once it has been lost

Question 17

Relative to coronary heart disease, why is there a major focus on dietary fat

Question 18

Generate a one-week menu using the MyPlate website. How do the choices compare to those in the DASH eating plan

Question 19

Identify and describe the following methods of measuring body composition: isotope dilution, potassium-40, ultrasound, bioelectrical impedance analysis, dual energy X-ray absorptiometry, skinfold thickness, and underwater weighing.

Question 20

Contrast the four-component and two-component models of body composition assessment.