Chapter 8 HUN

Excess energy is stored as fat

Fat is used for energy between meals

Energy balance: energy in = energy out

A shift in balance causes weight changes

Not simply fat changes




Intake greater than expenditure

Weight gain

3500 kcal in excess= 1lb body fat stored

(Classic but erroneous)

Limitations (gender, body composition etc.)


  • Intake less than expenditure

  • Weight loss

  • 1lb fat lost = 3500 kcal expended beyond those consumed

Hunger VS Appetite

Physiological response to nerve signals and chemical messengers

Hypothalamus

Influences 

Satiation – stop eating

Satiety – not to start eating again

  

 ENERGY BALANCE AND BODY COMPOSITION

   

Energy Balance

  • Excess energy is stored as fat

    • Fat is used for energy between meals

  • Energy balance: energy in = energy out

    • A shift in balance causes weight changes

      • Not simply fat changes

 

 

  • Intake greater than expenditure

  • Weight gain

  • 3500 kcal in excess= 1lb body fat stored

  • (Classic but erroneous)

  • Limiitations (gender, body composition etc.)

 

 

 

 

 Energy In: Food Intake

  • Hunger VS Appetite

    • Physiological response to nerve signals and chemical messengers

  • Hypothalamus

  • Influences

  • Satiation – stop eating

  • Satiety – not to start eating again

 

 

 

   

Energy In: Food Intake

  • Overriding hunger and satiety

    • Stress eating

  • External cues

  • Time of day, availability, sight, taste of food

  • Environmental influences

    • Examples

  • Cognitive influences

  • Disordered eating

 

 Energy In: Food Intake

  • The hypothalamus

    • Control center for eating

    • Integrates messages

      • Energy intake, expenditure, storage

    • Gastrointestinal  hormones

 

 Energy Out

  • Thermogenesis

    • Basal metabolism

    • Physical activity

    • Food consumption

    • Adaptation

   

Energy Out: Basal Metabolism

  • About two-thirds of energy expended in a day

  • Metabolic activities

    • All basic processes of life

    • Basal metabolic rate (BMR)

      • Variations

      • Weight

      • Lean tissue

  • Resting metabolic rate (RMR)

   

 

Factor

Effect on BMR

Age

Lean body mass diminishes with age, slowing the BMR." 

Height

In tall, thin people, the BMR is higher.

Growth

In children and pregnant women, the BMR is higher.

Body composition (gender)

The more lean tissue, the higher the BMR (which is why males usually have a higher BMR than females). The more fat tissue, the lower the BMR.

Fever

Fever raises the BMR.

Stresses

Stresses (including many diseases and certain drugs) raise the BMR.

Environmental temperature

Both heat and cold raise the BMR.

Fasting/starvation

Fasting/starvation lowers the BMR.

Malnutrition

Malnutrition lowers the BMR.

Hormones (gender)

The thyroid hormone thyroxin, for example, can speed up or slow down the BMR.Premenstrual hormones slightly raise the BMR.

Smoking

Nicotine increases energy expenditure.

Caffeine

Caffeine increases energy expenditure.

Sleep

BMR is lowest when sleeping


   

Energy Out: Physical Activity

  • Voluntary movement of skeletal muscles

  • Most variable component of energy expenditure

  • Amount of energy needed

    • Muscle mass

    • Body weight

    • Activity

  • Frequency, intensity, and duration

   

Energy Out: Thermic Effect of Food: the amount of energy your body uses to digest, absorb, and metabolize food

  • Acceleration of GI tract functioning in response to food presence

    • Releases heat

  • Approximately 10 percent of energy intake

  • High-protein foods vs. high-fat foods

  • Meal consumption time frame

 

 THERMIC EFFECT OF FOODS

  • Carbohydrate: 5-10%

  • Fat: 0-5%

  • Protein 20-30%

  • Alcohol 20%

 

 Energy Out: Adaptive Thermogenesis: the process of metabolic changes that occur in response to environmental temperature or diet changes

  • Adapt to dramatically changing circumstances

    • Examples

  • Extra work done by body

  • Amount expended is extremely variable

  • Not included in energy requirement calculations

  Components of

Energy Expenditure

Estimating Energy Requirements

  •   Gender

    • BMR

  • Growth

    • Groups with adjusted energy requirements

  • Age

    • Changes with age

  • ➢Physical activity

    • Levels of intensity for each gender

  • Body composition & body size

    • Height

    • Weight

 

 ESTIMATING BASAL ENERGY NEEDS

  • Men: (1.1 to 1.3 kcal/min)

  • or 24 kcal / kg /day

 

 

 DEFINING HEALTHY BODY WEIGHT

  • Body composition

    • Body weight = fat + lean tissue (including water)

    • Approx. 60% water

    • 20% fat

    • 10% protein and other nutrients

 

 Defining Healthy Body Weight

  • Body mass index

    • Relative weight for height

      • BMI = weight (kg)

height (m)2

  • Health-related classifications

    • Healthy weight: BMI = 18.5 to 24.9

    • Other classifications

  • Not a measure of body composition

    • Variations

 

Body Mass Index (BMI)

 

   

Body Fat and Its Distribution

  • Important information for disease risk

    • How much of weight is fat?

    • Where is fat located?

  • Ideal amount of body fat depends on person

   

Body Fat and Its Distribution

  • Needing less body fat

    • Some athletes

  • Needing more body fat

  • Alaskan Fisherman

  • Woman starting pregnancy

  • Fat distribution

    • Visceral fat (abdominal)

  • Central obesity ( trunk)

  • Waist circumference

  • Subcutaneous fat (under skin)

 

 BODY FAT RANGES

  • Normal man: % body fat

    • age 20 to 39 (8 to 19.9%)

    • Age 40 to 59 (11 to 21.9%)

    • Age 60 to 79 (13 o 24.9%)

  • Normal woman

    • Age 20 to to 39 (21% to 32.9%)

    • Age 40 to 59 (23 to 33.9%

    • Age 60 to 79 (24 to 35.9%


Methods Used to Assess Body Fat

  •  Fatfold measures

  • Hydrodensitometry

  • Bioelectrical impedance

  • Air displacement plethysmography

  • Dual energy X-ray absorptiometry (DEXA)

 

 Bioelectric impedance

a non-invasive method for measuring body composition by passing a weak electrical current through the body and measuring the voltage. BIA is based on the principle that different tissues in the body have different levels of conductivity, and that lean tissues like muscle and bone have greater conductivity than fat.

 

 

 FAT DISTRIBUTION


 CENTRAL OBESITY (upper body fat)

  • Intra-abdominal: around the organs of the abdomen

  • Increase risk of:

  • heart disease

  • stroke

  • Diabetes

  • Hypertension

  • Some types of cancer

 


  • Abdominal fat most common in men

  • Women post menopause

  • Lower body fat (hip and thigh)

    • Most common in women

    • Relatively harmless

 

 

 BODY SHAPES COMPARED

  • “Apple” & “Pear”

  • Android obesity (manlike)

  • Gynoid obesity (womanlike)

   

“Apple” and “Pear” Body Shapes Compared

 Body Weight, Body Composition, and Health

  •   Health Risks Associated with Body Weight and Body Fat

    • Health Risks of Overweight

  • Diabetes

  • Hypertension

  • Cardiovascular disease

  • Sleep apnea

  • Osteoarthritis

  • Some cancers

  • Gallbladder disease

  • Kidney disease

  • Respiratory problems –

Pickwickian syndrome

  • Complications in pregnancy and surgery

 

 Health risks of underweight

  • Malnutrition

  • Low resistance to disease

  • Menstrual irregularities

  • Infertility

  • Low birth weight babies

  • Bone fractures and osteoporosis

 

 Eating Disorders

  • Many individuals, including young females, suffer from eating disorders.

  • These include anorexia nervosa, bulimia nervosa and binge-eating disorders.

  • The causes include a combination of sociocultural, psychological, and perhaps neurochemical factors.

  • Athletes are among the most likely group to develop eating disorders.

 

 Anorexia Nervosa

  • Characteristics of Anorexia Nervosa

    • Self-starvation – tremendous self-control to limit eating

    • Physical consequences are major and life threatening.

  • Treatment is multidisciplinary

    • Food and weight

    • Relationships with self and others

 

 

 

 Bulimia Nervosa

  • Characteristics of Bulimia Nervosa

    • Binge eating – lack of control over eating, excessive kcalories from high-fat, low-fiber and high- carbohydrate foods eaten all at once

    • Purging – cathartic and/or emetic

  • Treatment of Bulimia Nervosa

    • Weight maintenance

    • Regular exercise

    • Counseling

 

 

 

 Binge-Eating Disorder

  • An unspecified eating disorder sharing some of the characteristics of anorexia nervosa and bulimia nervosa yet does not meet the criteria for diagnosis.

  • Lack of self-control over eating with binges

  • Consuming large quantities of food, eating quickly, feeling uncomfortably full, eating alone, and feeling disgusted or guilty

  • Marked distress

  • Occurrence of two times per week for six months

  • Not associated with compensatory behaviors