Unit 10: Body Weight and Weight
Management
My qualifications
Key Definitions
• All the following definitions are based on the
concept of an ideal weight
• Medical definition: the weight at which the
individual’s health risk is lowest
• Aesthetic definition: varies between culture,
individuals
Key Definitions
• An overweight individual exceeds their ideal
weight
• An overfat individual exceeds the
recommended amount of body fat by a
certain margin
• Obesity is a “large excess” above overfatness
It is possible to be overweight and not be overfat
Think Arnold
METHODS OF DETERMINING
“IDEAL WEIGHT”
Height Weight Tables:
Ideal weight as measured by MetLife insurance company
Doesn’t consider body composition
Only intended for people 25-59
Sample they used may not be representative
The weights suggested for tall people are unreasonably low
Body Mass Index (BMI)
 BMI = (body mass in kg)/ (height in metres)²
 Ex. My BMI = (155 lbs x 1kg/2.24 lbs)/ (1.7 m)²
 BMI = 23.94
 BMI above 25 = overweight
 BMI above 30 = obese
 Again, poor at accounting for body composition
 How much muscle do you have???
 However, simple to figure out
 Good for population-based analysis
BMI Classification
James, 2001
More Reliable Methods for Estimating
Body Fat
• Underwater weighing
• Sum of skinfolds
• electrical impedance
• CAT scan
OBESITY TRENDS/ STATISTICS
The Changing Size of North America
Healthcare Burden of Obesity
Health Risks of Overweight
 cardiovascular disease (CVD)
 hypertension
 Type II Diabetes
 pulmonary disorders
 sleep disorders (e.g. SLEEP APNEA)
 gout
 various cancers
 osteoarthritis
 early mortality
 depression
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Prevalence of obesity
• Higher in:
– Males compared to females
• However, women are more dissatisfied with weight than
men
– Even though their BMIs are lower, are less overweight and have a
higher prevalence of underweight
– Older people
– Poorly educated adults
– Rural (the country) compared to urban (the city)
habitants
– Low income groups vs. high income groups
CAUSES OF OBESITY
Causes of Obesity:
Causal Web
Kumanyika, 2002
Too linear, no feedback loops
Causes of Obesity:
Foresight Model
Take Home Message: Obesity is complex!
Feedback loops in the Foresight model convey the
complex nature of obesity and the various
interactions at play
Ex. Food Consumption
Foresight Causal Obesity Nodes
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•
•
•
•
•
•
Food Consumption
Individual Physical Activity
Individual Psychology
Social Psychology
Physical Activity Environment
Food Production
Physiology
Causes of Obesity: Food Consumption/ Individual
Physical Activity (Positive Energy Balance)
Physical Inactivity has increased
Food consumption
has increased
Energy Balance = energy intake – energy expenditure
Causes of Obesity: Individual Psychology
• Psychological and cultural factors
– ‘Hunger center’ in brain
• Receives sensory cues such as smell, sight, taste of food
• Constantly bombarded with pro-food consumption, anti-activity stimuli
• Receives cues from stomach when full
– Food sometimes represents love, happiness and security
– *** Food consumption and physical activity levels are
typically learned behaviours. If a behaviour is central to a
person’s normal behaviour, like smoking, it is often very
difficult to change.
Causes of Obesity: Social Psychology
• Obesigenic behaviour spreads through social networks based
more on psychosocial relations than biological or
environmental relations
– Close friendship with an obese person predicts obesity more than
living near obese people or familial relation to an obese person
(Christakis 2007)
Causes of Obesity: Food Production
(Social Psychology)
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Causes of Obesity: Food Production
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Causes of Obesity: Physical Activity
Environment
Causes of Obesity: Physiology
• Metabolic factors associated with < 2% cases of
obesity
– ex. Thyroid gland malfunction
• Hormonal factors hormones can influence
appetite and metabolic rate; improper sleep,
poor diet can affect their levels
• Genetic predisposition genes that influence
appetite and metabolism may have mutations
Is it physiologically more difficult to
lose weight after it is gained?
• The more you eat, the more your stomach learns to
accepts a larger amount of food before its stretch
signals fullness
• Fat gain occurs through: hyperplasia (increased fat
cell numbers) and hypertrophy (increase in size)
– Fat loss occurs through hypotrophy ONLY
• Which means once you gain fat cells, they never go away, they
only get smaller!!!
• Increase activity of lipoprotein lipase (LPL), a
molecule that stores fat, with weight loss!
Doesn’t that suck????!!!!
Why do some people gain weight
easily, while others do not?
• Thermogenic effect theory/thrifty gene
hypothesis
– Obese people are better at converting food to tissue
– Healthy weight people may “waste” energy as heat
• Set point theory: weight and %body fat
maintained around a narrow margin
– Metabolism speeds up when weight is gained, slows
down when weight is lost
– Evidence: some prisoners who were overfed never
gained weight, metabolic rate increased
EATING DISORDERS
Anorexia nervosa
Bulimia nervosa
Binge Eating Disorder
Night Eating Syndrome
Sleep-related Eating Disorder
Eating Disorders by the numbers
• Lifetime prevalence (2002)
– Anorexia- 0.9% women, 0.3% men
– Bulimia- 1.5% women, 0.5 % men
– Binge eating disorder- 3.5% women, 2.0% men
Anorexia Nervosa
• Anorexia = lack of appetite
• Nervosa means that it is a psychiatric disorder
• Those affected
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–
–
–
Have an intense fear of getting fat
Have a distorted body image
Do not understand how bad it is or why it started
Often think being thin is linked with beauty and/or
perfection
• Can slow growth and cause long term effects if
during adolescence
• Highest mortality rate of any psychiatric disorder!
Bulimia nervosa
• Bulimia = ‘great hunger’
• Involves periods of extreme overeating (binging) followed by
energy depletion either by vomiting, laxatives or excessive
exercise
• Warning Signs include:
– Preoccupation with food
– Distorted perception of body weight
– Frequent dieting
• Medical risks include
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–
–
–
Tooth decay
Stomach rupture
Tears in the esophagus
Irregular heart beat
Binge Eating Disorder
Eating Disorders
• Night Eating Syndrome
– The typical person with this controversial disorder:
•
•
•
•
•
Skips breakfast
Consumes approx half of their Calories after dinner
Binges on foods that are typically carbohydrate-dense
Suffers from depression/anxiety (guilt exacerbates condition)
Has difficulty sleeping
• Sleep-Related Eating Disorder
• A person with this disorder gets up in a sleep-walking state and
binges on excessive amounts of Calories
• Will eat strange combinations of food they would typically
never consume
Eating disorders
• Food is typically not the problem
• Often a larger psychological issue is at its base
– Obsession with perfection
– Distorted body image
– Child abuse; physical or verbal
• More often than not affects females
Body dissatisfaction and weight
• A significant portion of 5-year-old girls associate a
diet with food deprivation, weight loss and thinness
• 29% of girls in grade 10 engage in weight loss
behaviour
• 40% of grade 10 girls perceived themselves as too
fat
• Girls who are teased are 1.5 times more likely to
engage in extreme weight loss measures
• Adolescent girls who diet are 324% more likely to
be obese than those who don’t!! (Stice, 1999)
Body Image Rant
Take home message:
You are not your body! Looks fade, so it is critical to not base your self worth on your
appearance. Take care of yourself for your health!
Confidence is beautiful! Be proud of who you are and the body that you were given,
we are all beautiful in our own ways (super corny, but true!)
WEIGHT MANAGEMENT
Poor methods of Weight Reduction
• Fad diets: a ‘miracle’ way to drop a lot of weight, often
in a short period of time
– Most are only effective because they are a disguise for a
low-calorie diet
– Often you may lose weight in the form of body water,
muscle, not fat
– not nutritionally balanced
– Often too severe a reduction in caloric intake is prescribed
– Can actually lower metabolic rate!
– Cannot be maintained for long term
Poor methods of Weight Reduction
• Diuretics to increase urination
• Stimulants to suppress appetite
• Massage: no evidence to support: waste of
time!
• surgery:
– Jaw wired shut
– Stomach stapled
– Intestinal bypass
– liposuction
GUIDELINES FOR SOUND WEIGHT
CONTROL
Improve your Diet
• Balance is the key!
You should not be losing more than 1-2 lbs per
week
– More than this often results in future weight gain
– A 500 kcal drop per day is recommended
• There are many effective weight loss regimes
• Caloric intake should be reduced
– Portion control, nutrient dense foods, filling foods
– Don’t lie to yourself about what you are consuming!
• Be aware of what’s in what you are eating (see next slide)
Food Item
Energy (kcal)
Fat (g)
McDonald’s French Fries regular
570
30
McDonald’s Big Mac
540
29
McDonald’s Double Quarter Pounder
740
42
Burger King Whopper
670
39
Wendy’s Baconator
830
51
McDonald’s McChicken
360
16
Burger King Tendergrill
510
19
Burger King Onion Rings
500
25
Subway 6” Meatball Marinara
580
23
Subway 6” Philly Cheesesteak
520
18
Dairy Queen Turtle Pecan Cluster Blizzard Large
1480
84
Chocolate Extreme Blizzard Large
1430
68
Starbucks Caffe Vanilla Frappuccino Blended Beverage 16 oz
390
11
Caramel Macchiato with whole milk (16 oz)
270
10
White Chocolate Mocha
430
15
Tim Horton’s Boston Cream Donut
250
8
Tim Horton’s Walnut Crunch Donut
360
23
Tim Horton’s Chocolate glazed timbit
70
2.5
Tim Horton’s Chocolate Macadamia Nut cookie
240
12
Tim Horton’s Iced Cappucino (small) with cream
250
11
Changing eating habits
 It’s about the way you eat too!
 Don’t shop while hungry
 Don’t leave tempting food in sight
 Eat slowly
 Wait 20 minutes before eating again
 Buy smaller plates
 Have a food that signals the end of your meal (ie. Small
chocolate)
 Eat more, but smaller meals throughout the day to
control hunger
 Don’t skip breakfast
Improve level of Exercise
• Increases caloric consumption, boasts
metabolism
• Exercise helps maintain muscle mass, which
allows for greater metabolic rate
• Gives a toned look
• Helps relieve depression and anxiety
• Must think of it as a permanent change!
• Find activities you enjoy that you will incorporate
into the rest of your life
Peer Group Support/
Psychological Modification
• Group weight loss programs can be helpful
• Emotional eating can disguise an underlying
emotional conflict, counselling may help
• Everyone has a general idea of how much they
should exercise/ eat. This does not change
behaviour!
• You have to change the way you think, and
that isn’t easy!
• Keeping a journal of your thought
processes/talking to others can help