Weight Management (EXAM C) Flashcards
What percentage of Canadian adults have a healthy body weight?
- about 38%
What are some reasons Canadians’ fitness levels have plummeted?
- increased screen time in front of TVs and computers at home and work.
- greater dependence on cars.
- increased availability of convenience foods.
- deterioration in the quantity and quality of physical education
By 2021, what is the estimated % of males and females that will be overweight?
- females: 50%
- males: 70%
What is body composition?
- relative amount of fat mass (essential and storage) vs the amount of fat-free mass (bone, muscle, organs, water-in-the body)
What is subcutaneous fat?
- the fat just beneath the skin
- critical for normal body function
What is visceral fat?
- the fat inside the. abdominal wall and around the internal organs
- an excess leads to a greater risk of heart disease, insulin resistance, and metabolic syndrome
What is ectopic fat?
- the fat located on or within organs, such as the liver, heart, and brain
- increases the risk for metabolic syndrome, heart disease, and stroke
What is body max index?
- a measure of relative body weight that takes height into account and is highly correlated with more direct measures of body fat
- calculated by dividing total body weight in kg by the square of height in meters
- applies to adults only
What BMI number indicates being underweight?
- < 18.5 (less than)
- under nutrition, osteoporosis, & infertility
What BMI number indicates being a normal weight?
- 18.5-24.9
- few health risks
What BMI number indicates being overweight?
- 25-29.9
- Risks include Type II diabetes, hypertension, CVD, certain cancers
What BMI number indicates being obese?
- > 30
What does it mean to be overweight?
- body weight that falls above the recommended range for good health
What does it mean to be obese?
- the condition of having an excess of non-essential body fat
- having a body mass index of 30 or greater or having a body fat percentage greater than 25% for men and 33% for women
What are some limitations to BMI?
- muscular individuals may easily be considered overweight
- not useful for growing children, women who are pregnant or nursing or the elderly.
How is waist circumference used?
- Used with BMI as a practical indicator of excess abdominal fat and associated risks
- associated with increased risk of coronary heart disease, Type II diabetes, and hypertension in Caucasian men and women
What methods can be used to assess body composition?
- skin fold fat measurement
- hydrostatic weighing & bod pod
- bioelectrical impedance analysis (BIA)
- dual energy x-ray absorptiometry (DEXA)
What is the ideal body fat percentage for men and women?
- men: 7-25%
- women: 16-35%
What is the skin fold thickness assessment?
- a Caliper is used to measure subcutaneous fat; various sites (3-9) on the body are measured
What are the limitation to skin fold thickness assessment?
- need flawless procedure, proper formula, body fat distribution isn’t the same everywhere
How does the bod pod assess body composition?
- air displacement plethysmograph which uses whole-body densitometry
- Fast, non-invasive, correlates well with hydrostatic weighing
- well suited for special populations (children, elderly, obese, disabled)
What are some limitations to the bod pod?
- requires strict protocol attire (bathing suit/spandex shorts or equivalent + bathing cap)
- hydration status and increases in muscle temperature can influence results
What is hydrostatic weighing?
- technique for measuring the mass per unit volume of a living person’s body
- theory that an object displaces its own volume of water.
What are the limitations to hydrostatic weighing?
- expensive and requires a lot of space
- subjects must completely submerge themselves underwater and expel all of the air in their lungs
What is bioelectrical impedance analysis?
- low-level electrical current is passed through the body and impedance (Z) or opposition to the flow of the current is measured.
- resistance to flow is greater in individuals with large amts of body fat b/c adipose tissue is poor conductor of electrical current
What are some limitations to bioelectrical impedance analysis?
- 10% error rate
- significant changes in body water (water is a good conductor of electricity)
What is dual-energy x-ray
absorptiometry (DEXA)?
- X-rays are used to quantify the skeletal and soft-tissue components of body mass
- only 3% error rate
What are some limitations to dual-energy x-ray
absorptiometry?
- expensive, limited available, few technicians
How is lean body mass calculated?
- Body Fat in lbs = (Total Body wt) x (Body Fat % in decimal form)
- Lean Body Mass = Total Body wt - Body Fat in lbs.
Is obesity simply due to an energy imbalance (i.e. Kcal intake > Kcal expenditure)?
- its not as simple as that
Is obesity all genetic?
- genes are a component but not the be all end all
Does physical activity lead to long-term fat loss?
- yes, but nutrition is important too
What percentage of Canadian children are obese?
- 1/3
- rates are rising in children as young as two
- in Sask; 29%
- up to 70% of obese children will grow to be obese adults
How do genetics contribute to excess body fat?
- Estimates of the genetic contribution to obesity vary widely, from 25-40%
- 600 genes have been identified and associated with obesity
- genes influence body size and shape, body fat distribution, and metabolic rate
What is the probabilities of lean/obese parents having lean/obese children are:
- Lean x Lean = 90% lean, 10% obese
- Lean x Obese = 60% lean, 40% obese
- Obese x Obese = 20% lean, 80% obese
What causes obesity?
- genetic predisposition or children with obese parents tend to be obese themselves
- ghrelin: hormone that stimulates appetite
What is gherlin?
- a hormone that is produced and released mainly by the stomach with small amounts also released by the small intestine, pancreas and brain
- ‘hunger hormone’ because it stimulates appetite, increases food intake and promotes fat storage
What is leptin? (1994)
- a protein produced adipose tissue (subcutaneous fat) that is a hormone acting mainly in the regulation of appetite and fat storage
What does leptin do?
- key role in increasing satiety and energy expenditure through hypothalamus action
- stimulated by insulin, estrogen, glucocorticoids
- inhibited by androgens, growth hormone, FFA
How is metabolism a factor in contributing to excess body fat?
- key factor in the regulation of body fat and body weight and is influenced by heredity, behaviour, weight loss or gain, and exercise
How are hormones a factor in contributing to excess body fat?
- play a role in the accumulation of body fat, particularly in women during puberty, pregnancy, and menopause (estrogen, testosterone)
How are fat cells a factor in contributing to excess body fat?
- amount of fat stored is function of number and size of fat cells
- can vary in size (20-200 micrometers)
- the smallest fat cells found in abdominal deposits
What is juvenile-onset obesity?
- develops in infancy or childhood
- increase in the number of adipose cells
- adipose cells have long lifespan and need to store fat
- makes it difficult to lose fat (weight loss)
What is adult onset obesity?
- increase in the number of adipose cells
- adipose cells are larger (store excess amount of fat)
- if weight gain continues, more adipose cells develop
What are the three types of adipose cells?
- intracellular
- intraorgan
- subcutaneous
Can adipose cells be sex specific?
- yes
- men = trunks
- women = limbs, abdominal fat after menopause
What is android obesity?
- characterized by excess abdominal fat, fat is found in the abdominal wall and visceral mesentery
- more common in men
- associated with glucose intolerance, diabetes, and increased cardiovascular risk.
What is gynoid obesity?
- characterized by excess hip/femoral fat
- more common in women
- can increase the risk of breast cancer developing, or CVD
How is eating calorie-dense foods a factor in contributing to excess body fat?
- foods containing high-fat and high-sugar, relying on fast food or packaged convenience food, and restaurant portion sizes contribute to our overweight and obese society.
How is lack of physical activity a factor in contributing to excess body fat?
- has been declining in Canadians, as schools have cut back on physical education and recess, and most adults are inactive throughout the day.
- on avg North Americans exercise 15 min/day and watch 170 min of TV!
What are two main lifestyle factors that contribute the excess body fat?
- eating calorie-dense foods
- lack of physical activity
What are some general factors contributing to excess body fat?
- genetic, physiological, lifestyle, and psychosocial factors
What is the main psychosocial factor contributing to excess body fat?
- food as a means of coping
- eating can provide a powerful distraction from difficult feelings (boredom, anxiety, sadness, etc.)
What are some psychosocial factors contributing to excess body fat?
- food as a means of coping
- socioeconomic status
- When food is an integral part of familial or cultural gatherings and celebrations
Why don’t diets work?
- treatment requires long-term lifestyle changes, many people can’t commit
What is body image?
- the mental representation a person holds about his or her body at any given moment in time
- perceptions, images, thoughts, attitudes, and emotions about the body
What is resting metabolic rate?
- the energy required to maintain vital body functions
- respiration, heart rate, body temperature, blood pressure, while the body is at rest
