Download - 3 - Body Composition Notes
Unit 9 - Obesity to Underweight: The Highs and Lows of Weight Status
phed 2007
Body Composition: Obesity to UnderweightHealthy Body Weight
Science defines a healthy body weight based on _____________________ from all causes.
1. Weight for height
2. Fat _________________
3. Absence of __________ ______________ associated with obesity
(e.g. cholesterol, blood glucose, BP)
Measuring Body Composition
Body Mass Index (BMI) Defines average relative weight for height in people older than 20 years
Often correlates with degree of body fatness and disease risk
Calculated by _____________ your weight (kg) by your height (m2)
Does not distinguish between __________ and ___________________ tissue
Doesnt tell where fat is ____________
Groups for which BMI may not correlate with fat:
Athletes Pregnant and Lactating Women People Over 65 Canadian BMI Catergories
Underweight BMI < _____________
Healthy weight BMI ____________________
Overweight BMI _________________________
Obese BMI > _____________
Body Composition Body mass is made up of:
fat, muscle, bone & organs
essential fat: men 5%; women 12% - bone marrow, CNS, internal organs
Healthy % body fat: men 12-20%; women 20-30%
Risks from UnderweightBody fat: essential in manufacture of hormones; required component of every cell in the body and provides a cushion for internal organs.
Low body fat levels:
delayed physical maturation during adolescence
infertility
accelerated bone loss
problems that accompany starvation
threatens survival during famine or wasting diseases
Underweight BMIs below 18.5 kg/m
Underweight caused by: genetic tendency to be thin; Poverty ; Illness or voluntary restriction of food intake.
Underweight in developed nations results from illnesses such as: HIV/AIDS, pneumonia, Cancer ,
anorexia nervosa, restriction of food
Poverty
Some people underweight for height have healthy body composition
Unless health is compromised (fatigue, frequent illness, impaired concentration, apathy, or extreme intolerance to cold), there is little reason for concern about underweight.
Concerns with Underweight Below certain threshold may experience: Infertility; Depression; Abnormal hunger regulation; Unable to keep warm; Nutrient deficiencies or death Obesity Trends among Canadians (take your own notes here)
Risks from Overweight
Risk of dying increases proportionally with ____________________.
70% of obese people have at least one additional health problem
1. diabetes
2. hypertension
3. stroke
4. ______________5. ______________6. ________________ 7. certain types of cancer
8. arthritis
9. complications in pregnancy
Fat Distribution
- intra-abdominal obesity visceral fat
- central obesity
Excess fat in the chest and stomach areas (Apple-Shaped) = higher risk for diabetes, heart disease and hypertension than excess fat in the hips, thighs, and buttocks (Pear-Shaped).
Measures of Body Composition and Fat Distribution
1. Anthropometry
Fat Fold tests Use caliper to gauge thickness of a fold of skin on back of arm, sub sca, chest, abdomen Waist circumference Indicatior of fat distovution and abdomina fat
Women > 88 cm
Men >102 cm2. Density
Underwater Weighing3. Conductivity
Bioelectrical Impedance Radiographic techniques
4. Dual energy X-ray absorptiometry (DEXA)
use low dose x-ray absorption to measure lean and fat mass Measurement of Abdominal Fat
Waist circumference
Women >________ cm; Men >_________ cm (higher risk of central-obesity diseases)
How Much Body Fat Is Ideal?
Man of normal weight: ________________
Overfat: greater than 22%; 25% if over 40 years
Female of normal weight: ______________
Overfat greater than 32%; 35% if over 40 years
The Mystery of Obesity
Causes of obesity are complex
Influences on obesity are multiple
1. Diet
2. Physical inactivity3. Environmental exposures
4. Genetic factors
5. Socio-economic status
Genetics and Obesity Single gene mutations are rare Few genetic differences are known to cause obesity Most people have an inherited tendency to obesity which is compounded by poor lifestyle choices
Obesity rates have greatly increased yet human genome has remained relatively constant
Physical Inactivity and Obesity
Fitness of Canadian adults has declined since 1980s (Tremblay, 2009)
Low activity relates to obesity
All activity has become voluntary Physical activity traded for time, convenience and personal fat stores
TV watching and computer use (Fulton, 2009)
Active lifestyle = walking 1hr/d
External Factors Promoting Obesity
Variety of delectable foods
Emotions (loneliness, cravings, depression etc.)
Time of day
Stress
High calorie, inexpensive foods
Advertising
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