Body Composition: Understanding Fat and Lean Tissues
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Questions and Answers

What are the two major body compartments that the human body is composed of?

Fat-free mass (lean tissues) and total body fat.

What is the main difference between subcutaneous fat and visceral fat?

Subcutaneous fat is located just beneath the skin, while visceral fat is located around internal organs.

What are the two main components of total body fat?

Essential fat and adipose tissue.

What is the function of adipose cells in the body?

<p>Adipose cells remove excess fat from the bloodstream for storage.</p> Signup and view all the answers

What happens to the size of adipose cells when the amount of fat stored increases?

<p>The size of each cell expands.</p> Signup and view all the answers

What is the result of brown fat and beige fat cell activity?

<p>The body wastes energy as heat (thermogenesis).</p> Signup and view all the answers

Why is it important to have healthy amounts of body fat?

<p>Because essential fat is vital for survival.</p> Signup and view all the answers

What is the consequence of having excessive amounts of fat stored in adipose tissue?

<p>It interferes with normal cell function and contributes to inflammation.</p> Signup and view all the answers

What is the primary function of adipose cells in regulating body temperature?

<p>Releasing fat for other cells to use as fuel when the body needs energy.</p> Signup and view all the answers

What is the result of adipose cells continuously releasing fat?

<p>The body eventually loses weight.</p> Signup and view all the answers

What role do adipose cells play in addition to storing and releasing fat?

<p>Secreting hormones and other substances that regulate food intake, glucose metabolism, and immune responses.</p> Signup and view all the answers

What is the primary function of subcutaneous fat?

<p>Insulating the body against cold temperatures and protecting muscles and bones from bumps and bruises.</p> Signup and view all the answers

What is the characteristic of subcutaneous fat distribution in men's and women's bodies?

<p>It is unevenly distributed, especially in the abdominal area, thighs, and buttocks.</p> Signup and view all the answers

What is visceral fat located in?

<p>The omentum, a structure under the abdominal muscles and hanging over the intestines.</p> Signup and view all the answers

What are the risks associated with excessive visceral fat?

<p>Type 2 diabetes and cardiovascular disease (CVD).</p> Signup and view all the answers

Why is it important to know your body composition?

<p>To predict the risk of obesity-related diseases.</p> Signup and view all the answers

What is the principle behind underwater weighing?

<p>Lean tissue is denser than water; fat tissue is not as dense as water.</p> Signup and view all the answers

What is the purpose of dual-energy x-ray absorptiometry (DXA)?

<p>To scan the entire body and assess body composition.</p> Signup and view all the answers

What is the primary principle behind bioelectrical impedance method of estimating body fat content?

<p>The principle that water and electrolytes conduct electricity, whereas fat tissue resists the flow of electricity due to lower water and electrolyte content.</p> Signup and view all the answers

What is the major limitation of using DXA for body fat estimation?

<p>The equipment is very expensive and not widely available outside of clinical settings.</p> Signup and view all the answers

What is the main reason why skinfold thickness measurements may underestimate total body fat?

<p>The technique may underestimate total body fat when used on overfat subjects.</p> Signup and view all the answers

What is the significance of estimating body fat content using percentage values?

<p>Percentages of body fat can be used to develop weight classifications for adults, indicating if an individual is overweight or not.</p> Signup and view all the answers

Why is it important to consider hydration status when using bioelectrical impedance method?

<p>Dehydration results in an overestimation of total body fat.</p> Signup and view all the answers

What is the primary purpose of taking skinfold thickness measurements at multiple body sites?

<p>To estimate total body fat content by measuring the depth of subcutaneous fat at each site.</p> Signup and view all the answers

What is the main advantage of using air displacement method for body composition assessment?

<p>It provides highly accurate estimates of body fat content.</p> Signup and view all the answers

Why do healthy young women have more body fat than healthy young men?

<p>Women need the extra fat for hormonal and reproductive purposes.</p> Signup and view all the answers

What is the limitation of bioelectrical impedance devices available for consumer use?

<p>Scientific data about the machine’s accuracy is lacking.</p> Signup and view all the answers

What is the significance of visceral fat in relation to overall health?

<p>Too much adipose tissue, especially visceral fat, can interfere with the body’s ability to function normally.</p> Signup and view all the answers

According to the table, what percentage of body fat is considered healthy for adult women?

<p>23-31%</p> Signup and view all the answers

Why may some additional fat in elderly persons not necessarily contribute to serious health problems?

<p>The extra fat may provide an energy reserve for a very ill person who cannot eat, and the extra padding of fat may protect a person from being injured by falling.</p> Signup and view all the answers

What is the classification for adult men with a body fat percentage of 28%?

<p>Obese</p> Signup and view all the answers

What is the body fat percentage range for adult women considered extremely obese?

<p>43% or more</p> Signup and view all the answers

Why is it essential to maintain a healthy body fat percentage, especially in adulthood?

<p>To avoid health problems, as excessive body fat contributes to various health issues.</p> Signup and view all the answers

What is the source of the information presented in Table 10.3?

<p>Food and Nutrition Board, National Institute of Health: Dietary Reference Intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients).</p> Signup and view all the answers

Study Notes

Body Composition

  • The human body is composed of two major compartments: fat-free mass (lean tissues) and total body fat.
  • Fat-free mass is composed of body water, mineral-rich tissues such as bones and teeth, and protein-rich tissues, including muscles and organs.
  • Total body fat includes “essential fat” and adipose tissue.
  • Essential fat is vital for survival and is found in cell membranes, certain bones, and nervous tissue.

Adipose Tissue

  • Adipose tissue contains white adipose cells (fat cells) that are specialized for storing energy in the form of triglycerides.
  • When food is plentiful, adipose cells remove excess fat from the bloodstream for storage.
  • As the amount of fat stored in adipose cells increases, the size of each cell expands, and the body gains weight.
  • The body develops more fat cells when overeating occurs in adulthood, especially in cases of extreme obesity.
  • Adipose cells secrete hormones and other substances that have roles in regulating food intake, glucose metabolism, and immune responses.

Subcutaneous Fat and Visceral Fat

  • Subcutaneous fat helps insulate the body against cold temperatures and protects muscles and bones from bumps and bruises.
  • Subcutaneous fat is unevenly distributed, with thicker layers in certain regions of men’s and women’s bodies, especially in the abdominal area, thighs, and buttocks.
  • Visceral fat is in the omentum, a structure that is under the abdominal muscles and hangs over the intestines.
  • Visceral fat makes substances that cause inflammation in the body, increasing the risks of type 2 diabetes and cardiovascular disease.

Measuring Body Fat

  • There is no direct way to measure a living person’s percentage of body fat.
  • Indirect methods of assessing body composition include:
    • Underwater weighing: comparing a person’s weight on land to their weight when completely submerged in a tank of water.
    • Dual-Energy X-Ray Absorptiometry (DXA): uses multiple low-energy x-rays to scan the entire body and provide a detailed picture of internal structures, including fat deposits.
    • Air displacement: measures the volume of a person’s body, which can be used to calculate their body composition.
    • Bioelectrical impedance: sends a painless, low-energy electrical current through the body to estimate total body fat.
    • Skinfold thickness: measures the thickness of subcutaneous fat at multiple body sites.

Importance of Healthy Body Fat

  • Some body fat is essential for good health, but too much adipose tissue, especially visceral fat, can interfere with the body’s ability to function normally.
  • Percentages of body fat can be used to develop weight classifications for adults.
  • According to one classification system, a man is overweight when his body is 22 to 25% fat, and a woman is overweight when her body is 32 to 37% fat.

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Description

Learn about the two major body compartments, differences between subcutaneous and visceral fat, and methods of measuring body fat. Understand the importance of healthy amounts of body fat.

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