Deck 10: Body Weight and Composition for Health and Sport

Question 1

List and describe five different techniques used to evaluate body composition, and highlight at least one value of each.

Answer 1

The human body consists of many elements nearly about 96% are carbon, hydrogen, oxygen and nitrogen, which acts as a structural basis for the body composition and the remaining 4% is composed of macrominerals and microminerals. In order to evaluate the body composition different techniques are used and the body composition can be measured at atomic, molecular, cellular, tissue-system and the whole body level.
The techniques used to evaluate the body composition are as follows:
1. Hydrostatic weighing: The hydrostatic weighing is also called as underwater weighing or hydrodensitometry. In hydrostatic weighing the body is submerged in a fluid and the buoyancy force acting on the body is measured, which is directly related to volume of displaced water.
As the fat is less dense, the bone and muscle tissues are denser than the water, a greater buoyant effect is observed than the corresponding bone weight and muscle tissue. The observed displace is exhibited by the large volume of water displaced in the weight of fat.
2. Air displacement plethysmography: The air displacement plethysmography or body plethysmograph is another volumentric technique used to evaluate the body composition. The individual is placed in a dual-chamber plethysmograph designed to evaluate the amount of wieght the individual displaces.
3. Skin folds: The skin fold technique is designed to measure the subcutaneous fat thickness in millimeters at a particular anatomical site. The thickness of the skinfold values estimate the body density, which may also be used to estimate percentage of body fat.
4. Bioelectrical Impedance Analysis (BIA): The BIA is a more expensive technique in which a low voltage current is optimally conducted through the body. The current is conducted through a high fat-free mass (high water content) while high-fat mass (low water content) gives resistance to current. The less the resistance, the greater is the water content and hence, greater the body density.
5. Dual energy X-ray Absoptiometry (DEXA): The DEXA technique is computerized X-ray technique, which is used to image the body tissues, in order to evaluate the bone mineral content, body fat and fat-free mass. The DEXA measures the body fat by releasing small doses of radiation through the body and a detector can evaluate as fat, bone or lean tissue.

Question 2

Which of the following best describes the role of leptin in the human body?

A) It is secreted by the hypothalamus and stimulates lipolysis in adipose cells.
B) It is secreted by the liver and inhibits the digestion of fats.
C) It is secreted by the adipose cells and inhibits hunger.
D) It is secreted by the stomach and stimulates appetite.
E) It is secreted by the intestines and stimulates appetite.

Answer 2

Leptin and ghrelin are the two hormones regulating the appetite. Ghrelin is secreted by gastric mucosa, and it is having opposite effects to leptin, it induces the feeling of hunger.
Leptin is not secreted by the hypothalamus, liver, or intestine.
Thus, the options (a), (b), (d), and (e) are incorrect.
Leptin is the hormone of adipose tissue, released by adipose cells during the triglyceride synthesis.
The appetite center is located in the hypothalamus. Leptin suppress the appetite center and the feeling the appetite also suppresses (it causes a feeling of satiety). Ghrelin stimulates the appetite center.
Thus, the correct option is,

Question 3

Discuss the set-point theory of body-weight control and relate it to body-fat levels, leptin, and neuropeptide Y.

Answer 3

The set point theory proposes the body should be in a certain weight. The important regulator for set point is hypothalamus. The hypothalamus regulates the intake of energy and the body weight, comparable to act as a thermostat in regulating the body temperature. Any increase in the normal body weight would lead to decrease in the appetite or enhance the basal metabolic rate, that would cause weight loss.
The various control centers in the hypothalamus are influenced by the feedback from the body. The feedback mechanisms of the body like blood concentration of glucose and other nutrients, that affect the pleasure center in the brain, which can influence the hypothalamus.
Exercise may influence the hypothalamus in different ways like stimulating the secretion of different hormones by the endocrine glands in the body. Further, stimulates the temperature control center and modifies the blood levels, that affect energy intake and output. The neuropeptide Y (NPY) neurons in hypothalamus, senses the glucose, leptin and adipokine secreted by the adipose tissue.
The human obese (OB) gene in adipose cells encodes and produces regulating peptide hormone called leptin. The leptin suppresses the food intake, decreases the appetite and induce the weight loss. When the storage of fat is high, then leptin production is also high. The NPY, stimulates the appetite, enhances the energy and reduces Resting Energy Expenditure (REE), which is inhibited by the blood borne leptin and suppress the hunger and voluntary food intake.
The greater the fat, the greater will be the leptin secretion, which inhibits the appetite stimulator by NPY. Further, decreased secretion of leptin results in the increase of NPY by the hypothalamus.

Question 4

Which of the following statements regarding android/gynoid obesity is false?

A) Gynoid obesity is associated with a higher incidence of certain diseases, such as hypertension.
B) Android obesity is characterized by excess accumulation of fat deposits in the abdominal area.
C) Android obesity is seen more often in men, while gynoid obesity is more prevalent in women.
D) Gynoid-type fat deposits are more resistant to weight loss compared to android obesity.
E) Development of both types of obesity is influenced by heredity.

Question 5

List the various genetic and environmental factors that may be involved in the etiology of obesity. Highlight two of each and explain their possible role.

Question 6

If a skinfold technique for body composition has a standard error of estimate of 3 percent, you can have 70 percent confidence that for a person who has a predicted body fat of 18 percent, the actual value is within a range of

A) 6-18 percent
B) 18-21 percent
C) 12-24 percent
D) 15-21 percent
E) 18-30 percent

Question 7

Explain the metabolic syndrome and associated health risks.

Question 8

Which of the following ranges of the Body Mass Index (BMI) is indicative of a normal height to weight relationship?

A) 5-8
B) 10-12
C) 15-17
D) 20-22
E) 27-28

Question 9

List the three components of the Female Athlete Triad. Discuss the underlying theories regarding its etiology, the potential effects on hormonal status, and subsequent serious health problems.

Question 10

In which sports might the condition of anorexia athletica appear to be more prevalent?

A) football and basketball
B) swimming and baseball
C) wrestling and field hockey
D) ballet and gymnastics
E) tennis and golf

Question 11

The set-point theory of weight control is based upon a feedback system, suggesting that the individual is programmed to be a certain body weight and that the body will always attempt to maintain that weight by regulating hunger and metabolism. What part of the body is believed to be the regulatory center for the control of the various feedback mechanisms?

A) liver receptors
B) stomach receptors
C) blood receptors in the kidney
D) receptors in the hypothalamus in the brain
E) receptors in the small intestine where absorption takes place

Question 12

The disorder of bulimia, which is often characterized by the binge-purge syndrome, is found

A) only in those with anorexia nervosa
B) only in extremely underweight individuals
C) only in normal-weight individuals
D) only in moderately or morbidly obese individuals
E) in individuals across the body-weight spectrum

Question 13

Which of the following is mainly an environmental rather than a possible hereditary factor in the multicausal etiology of obesity?

A) a sedentary lifestyle
B) hormonal imbalance
C) disorder in the brain's hunger and satiety centers
D) lower basal metabolic rate
E) a higher set point

Question 14

Obesity has been associated as a potential risk factor in all the following diseases or health problems except which one?

A) coronary heart disease
B) anemia
C) hyperlidemia
D) diabetes
E) hypertension

Question 15

Protein consumed during a starvation-type diet most likely will be:

A) used to rebuild muscle tissue
B) used to replace worn-out cells
C) converted to glucose for energy
D) used to stabilize fluid balance
E) stored as fat