Energy Balance and Body Composition

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Energy Balance and Body Composition

• Chapter 8

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Energy Balance

• 1. Positive energy balance
• Energy IN gt Energy OUT
• result stored in adipose tissue
• necessary during pregnancy, growth.
• 2. Negative energy balance
• Energy IN lt Energy OUT
• result weight loss

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Weight Maintenance

• Energy IN Energy OUT

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Determining Energy Composition

• Bomb calorimeter.
• Burns food and measures the amount of heat given
  off this is a direct measure of foods energy
  value.
• Chemical bonds break and release energy.
• 1kcal energy required to increase 1kg water 1oC.

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What is hunger?

• The feeling that prompts thoughts of food and
  motivates food consumption.
• A physiological response a feeling.
• Influenced by nutrients in the bloodstream,
  eating patterns, climate, etc.

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What is hunger?

• Appetite-
• Signals that guide dietary selection.
• Comes from a psychological state.
• Can have physiological dimensions (desire for
  a certain food).

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What is hunger?

• Satiety-The brain signals the body to stop
  eating (hunger is suppressed).
• 1. Sensory stimulation meal was eaten.
• 2. Effects of nutrient digestion, absorption and
  metabolism are felt.
• 3. Over time, lack of food leads to lack of
  satiety.
• 4. The cycle begins again.

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Internal Forces that regulate satiety

• Cholecystokinin (CCK) and GI distention register
  satiety.
• The hypothalamus As the sympathetic nervous
  system declines, food intake increases the
  opposite is true.
• Increased nutrients in the blood.
• Hormonal and drug affects.

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Energy use by the body

• 1. Basal thermogenesis
• (basal metabolism)
• 2. Exercise-induced thermogenesis
• (physical activity)
• 3. Diet-induced thermogenesis
• (thermic effect of food)
• 4. Adaptive thermogenesis
• (energy of adaptation)
• Thermogenesis The bodys generation of heat.

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Energy use by the body

• 1. Basal metabolism
• Defined Basic functions in the human body that
  support life.
• BMR (Basal metabolic rate) The rate at which the
  body spends energy for maintenance activities.
• Rates vary with age, height, activity, etc.

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Energy use by the body

• 2. Physical Activity
• Defined Voluntary movement of the skeletal
  muscles and support systems.
• The muscles need energy to move
• Influenced by duration, frequency and intensity.
• Energy expended depends on muscle mass, body
  weight and activity.

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Energy use by the body

• 3. Thermic effect of food
• Defined The energy required to aid in
  digestion, absorption, transport and metabolism
  of food.

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Energy use by the body

• 4. Adaptive thermogenesis
• Defined Adjustments in energy expenditure
  related to changes in environment, physiological
  events, trauma or hormone status.

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Body Composition

• Muscle, bone, fat and tissue that make up a
  persons body weight.
• Body weight fat lean tissue (including H2O)
• A persons weight does not accurately
• represent their body composition.

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What is a healthy body weight?

• Identify weights associated with good health and
  longevity.
• Weight within the suggested range for height.
• Fat distribution at low risk of illness and
  premature death.
• Medical history without risk factors of obesity
  blood pressure, blood cholesterol, etc.

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Body Mass Index (BMI)

• Describes relative weight for height.
• Healthy weight BMI 18.5-24.9
• Underweight BMI below 18.5
• Overweight BMI above 25
• Average BMI in the U.S. 26.5

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Overweight v. Overfat

• Health risks of being obese apply to people who
  are overfat
• Men gt25 body fat
• Women gt 30-35 body fat
• Measuring body fat
• Underwater weighing (most accurate)
• Skinfold thickness
• Bioelectrical impedance

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How much body fat?

• It depends on the individual person.
• Women naturally have more body fat
• 18-32.
• Men may have 10-25 body fat.
• Athletes need less body fat.
• Pregnant women, people living in colder climates
  need more body fat.
• A person should have enough body fat to meet
  basic needs but not too much to incur health
  risks.

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Distribution of body fat

• Critical to health.
• Intra-abdominal fat stored around the organs of
  the abdomen. (Apple shape)
• Increased risk of heart disease, stroke,
  diabetes, hypertension and some cancers.
• Lower-body fat stored around the hips and
  thighs. (Pear shape)
• Less susceptible to health problems.
• Most common in women during reproductive years.

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Body Types

• Apple shape
• Intra-abdominal fat.
• Common in men.

• Pear shape
• Lower-body fat
• Common in women.

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Health Risks and Body Weight

• Underweight
• Malnutrition, Illness, Smoking habits, Extreme
  physical activity.
• Inadequate immune response and decreased ability
  to fight disease.
• Infertility.
• Osteoporosis and bone fractures.
• Increased weight increases health.

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Health Risks and Body Weight

• Overweight
• Increased risk of diabetes, hypertension, heart
  disease, respiratory disease, etc.
• Increased mortality.
• Weight gain gt20 lbs in adulthood correlates with
  increased mortality.
• Normal weight and unfit people have increased
  mortality.
• Decreased weight increases health.

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Health Risks and Body Weight

• Heart disease (CHD)
• Obesity and heart disease are related.
• Central obesity is especially harmful.
• Inactivity is harmful.
• Obesity increases risk factors for CHD.
• Weight loss can lower risk factors for CHD.

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Health Risks and Body Weight

• Diabetes
• 2x more likely to develop in an obese person.
• Central obesity is related to diabetes.
• Increased insulin resistance in obese people.
• Weight gain (11-24 lbs) since age 18 doubles the
  risk of developing diabetes.
• Weight loss improves glucose tolerance and
  insulin resistance.