WEIGHT CONTROL
OBESITY AND OVERWEIGHT
• Major problem in US
• Associated with high risk of health problems
• Linked to 5 out of 10 top causes of death:
heart disease
cancer
stroke
diabetes
atherosclerosis
• Negative impact on quality of life:
prejudice against overweight
job discrimination
social isolation
ridicule, rejection
UNDERSTANDING
• Consequences of obesity better understood than causes
• Obesity = positive energy balance
• Kcal intake greater than kcal output
CAUSES
• NATURE (INTERNAL)
• Genetic
• Inborn traits
• NURTURE (EXTERNAL)
• Environmental factors
• Early childhood
• Exercise patterns
• Stress
• Etc.
NATURE THEORY
GENETICS
• Born with tendency to become obese
• Obesity tends to run in families
if 0 parent obese = 14% chance
if 1 parent obese = 40-60% chance
if 2 parents obese = 80-90% chance
• Genetics or learned behavior?
twin studies – more like biological than adopted
raised apart tend to have similar height and weight similar to biological
parents
LEPTIN
• Compound called “leptin” made in fat cells hypothalmus in brain
RAT-HYPOTHALMUS
SET POINT THEORY
• Body defends its weight
• High set point = obesity
ENZYME THEORY
• Lipoprotein lipase
• High amounts = high fat storage
FAT CELL THEORY
• Development of excess fat cells during childhood
• High lipoprotein lipase?
• Very efficient at storing fat
FAT CELL THEORY
THERMOGENESIS THEORY
• Ability to convert energy to heat
• Inefficient = need more kcals (thin)
• Efficient = need fewer calories (obese)
• Inborn differences in thermogenesis
• Only 4 of 10 obese children become obese adults
• Most obese adults were normal weight infants and children
NURTURE THEORY
EATING HABITS
• Overeating habits formed in childhood
• Eat to satisfy hunger plus reasons unrelated to needs for food:
relieve boredom
stress
food = love
food to reward good behavior
social occasions
please parents = clean plate club
• Therefore, other eating signals replace hunger
• Early habits difficult to change
PHYSICAL ACTIVITY
nd
• 2 reason not related to genetics
• Often overweight and correct weight consume same number of calories
but overweight very sedentary
• Over time less active will gain weight
BODY WEIGHT
OPTIMAL WEIGHT
• Height – weight charts
• Life insurance data collected since 1919 standard or ideal weight
• Weight only NOT body composition: lean vs fat
• Underweight = 120%
HEIGHT – WEIGHT CHARTS
HAMWI FORMULA
• Estimate optimal weight with formula commonly used
• Females
5 ft = 100 # add 5# for each inch over 5 ft.
• Males
5 ft = 106# add 6# for each inch over 5 ft
BODY MASS INDEX
• Relationship of weight to height
• Weight (kg)/ Height (m)2
• Correlation between BMI and risk of complication from obesity
• Correlation between BMI and risk of mortality
PERCENT BODY FAT
• Weight in pounds not whole story
• Body builder, football player appear overweight but have lean not fat
• Sedentary person at “ideal weight” but flabby lean fat
• Therefore, % fat & % lean are better estimate of health risk than just
weight
BODY FAT AND HEALTH
• Total for normal situations:
Men: 12-20%
Women: 20-30%
• Health problems when body fat exceeds:
20% in young men 25% in older men
30% in young women 35% in older women
• Minimum with good health:
Men: 3-4%
Women 10-12%
ESSENTIAL FAT
• Stored in marrow of bone, heart, lungs, liver, spleen, kidneys,
intestines, muscles, CNS
• Required for normal physiologic functioning
• Men: 5-10% fat
Reference man= 3% fat
• Women: 12-16% fat
Reference woman = 12-14% fat
Includes gender specific fat – mammary glands and pelvic region
STORAGE FAT
• Adipose tissue – protects various internal organs, beneath skin surface
• Men: 12% fat
• Women: 15% fat
17% critical level for menses onset
22% to maintain
BODY COMPOSITION
SKINFOLD MEASUREMENTS
• About ½ of all fat right under skin
• Measures thickness of fat layer just below skin to estimate body fat
• Uses calipers
• Measure in different places for male or female
• Plug measurements into equation = % body fat
• Fairly accurate if measurer is trained and experienced
• Portable, calipers = $200
CALIPERS
BIOELECTRIC IMPEDANCE ANALYZER
• BIA – newer method
• Fat poor conductor of electricity
• Water and muscle good conductor
• BIA measures how quickly electrical current passes through body
• Fast = lean Slow = fat
• Can be fairly accurate but person must be properly hydrated
• $6,000 / Machine
UNDERWATER WEIGHING
• Most accurate way to estimate % body fat
• Uses expensive, non-portable equipment
• Weigh on dry land, then under water
• The less you weigh in the water, the greater the fat content
• Fat is more buoyant (floats) than muscle
HYDRODENSIOMETRY
PREVENT OBESITY
• Best attack on obesity is prevention
• Goal of weight loss = body fat
• 3 part approach
Diet
Physical activity
Behavior modification
HEALTHY WAY TO LOSE WEIGHT
DIET
• Create negative energy balance
• Well-balanced diet
• Don’t eliminate food groups
• Variety with controlled portions
• Kcals not below 1200 for females; 1400 for males
• use of nutrient dense foods
• use of fat foods – you do need some fat
PHYSICAL ACTIVITY
• Schedule activity, keep schedule
• Vary activities to decrease boredom
• Change lifestyle to use kcals
BEHAVIOR MODIFICATION
• Keep diary to find cues for eating
• Once you know cues can gain better control of them
• Only make 1-2 changes at once – more is overwhelming
REALISTIC EXPECTATIONS
• 1-2 pounds per week
• More = thyroid, BMR, loss of muscle
POPULAR APPROACHES TO WEIGHT LOSS
THAT DON’T WORK
WEIGHT LOSS DIETS
• Books, programs that promise quick painless weight loss
• Reliability
• Promises
• Restrict calories and/or food choices – any diet low in calories will =
loss – how much fat? How much lean?
• Brain needs glucose
• Glucose from protein – break down muscle
EXAMPLES
• Fasting (0 kcals/day) vs semi-fasting (400-800 cals/day
• Optifast, slimfast, HMR, etc.
• Need close medical supervision
• Lose fat and a high percent of lean
• Lose fluids, electrolytes
• CHO have H20 losses + minerals dissolved in H2O (potassium = K+)
• K+ = irregular heart rythms & death
• Don’t learn to change eating habits
SIDE EFFECTS OF VERY LOW CALORIE DIETS
• Decreased BMR
• Fluid imbalance/dehydration
• Insomnia
• Dry skin and hair
• May regain weight due to inability to make long term changes
LOW CHO DIET
• High weight loss at first = water, NOT fat
• CHO glycogen + water with glycogen body weight
• But when CHO glycogen + water = weight
• Also, CHO intake = amount lean converted to glucose (CHO) for
brain, CNS
ORGANIZED WEIGHT LOSS PROGRAMS
• Group support, encouragement
• Weight watchers, Jenny Craig
• Flaws –
• ? Diet counselors
• Regular foods vs pre-packaged
• ? Stress behavior change, exercise
• Lack of reliable data on permanent weight loss = testimonials, before or
after
DRUGS OR DIET PILLS
• Non-prescription = phenylpropanolamine (PPA) – chemical structure
similar to amphetamines (speed)
• Flaws:
• Suppress appetite 1-2 months
• Harmful side effects = nervousness, irritability, insomnia, BP (strokes)
• Still must restrict kcals - so why take pills
PRESCRIPTION DRUGS
• Meridia = keeps serotonin levels by preventing breakdown
? Addictive + need kcals
• Xenical – Spring 1999
absorption of fat and fat soluble vitamins
causes changes in bowel habits (fat malabsorption)
requires kcal & fat diet
slow, steady 10% weight loss
OTHER MEASURES
• Liposuction
• Wire jaws shut
• Balloon in stomach
• Surgery – gastric stapling, bypass
BILIPANCREATIC DIVERSION
• With duodenal switch
• Risk of nutritional deficiency
• Must meet nutritional requirements
• Permanent change
TREATMENT
• Most don’t work – no magic
• Only 5-20% who , keep it off after 1 year
ID FAD DIETS
• Advocates unusual foods or supplements
• Eliminates or singles out foods/food groups
• Claims no effort, no hunger
• Weight loss claims not realistic
• No exercise needed
• Promoter is manufacturer or is paid by manufacturer
• Children should maintain weight – NO diet – grow into height