Chapter 9: Weight Management

Overweight and Obesity

major problem in US, especially compared to other developed countries
risk factors include tobacco, poor diet/inactivity, alcohol, microbial/toxic agents, etc.
prevalence continues to increase
- women, poor, Black and Mexican Americans, children
- obesity affects 1.9 billion adults and 41 million children <5 years
industrialized food system contributor
- abundant energy-dense, processed, affordable food products

Body Mass Index (BMI)

Body Mass Index (BMI) → measure of relative weight for height

1 lb = 0.454 kg; 1 in. = 2.54 cm

Underweight → <18.5

Normal Weight → 18.5 < U < 25

Overweight → 25 - 29.5

Obese → >30

Underweight

< 2% in US
causes of underweight:
- genetics, hunger, appetite, satiety irregularities, psychological traits, metabolic factors
- high demand for energy to support physical activity and growth
underweight vs. anorexia nervosa
- anorexia nervosa sees starvation as intentional
weight gain → lack of physical activity and high energy intake

Problems of Overweight and Obesity

Health Risks with being Underweight

body weight and fat distribution correlate with disease risk and life expectancy
risks associated with being underweight:
- wasting diseases
- menstrual irregularities and infertility
- osteoporosis and bone fractions

Health Risks with being Obese

obesity designated disease
health risks → cardiovascular disease, type 2 diabetes, cancer, metabolic-dysfunction
higher likelihood of being disabled in later years
high medicals costs and lost productivity

Fat Cell Metabolism

Fat Cell Development

energy in > energy out
fat cells of
amount of fat in adipose tissue reflects number and size of fat cells
hyper-plastic obesity vs. hyper-trophic obesity
- hyper-plastic → increase number of fat cells
- hyper-trophic → increase size of fat cells

fat cell numbers increase during childhood and adolescence
as fat cells accumulate triglycerides, they expand in size
energy out > energy in
- fat cell size shrinks → no change in number of cells

Fat Cell Metabolism

Set Point Theory →

related body weight processes that body tends to maintain certain weight through internal control
- blood glucose, pH, and body temp.
with weight gain/loss body adjusts in attempt to return to previous state

Causes of Overweight and Obesity

Obesity Gene

ob Gene → obesity gene

gene codes for protein Leptin
acts as hormone in hypothalamus
promotes negative energy balance, suppresses appetite, and increases energy expenditure
Leptin injections effective in reducing body weight in humans/animals

Environment

obesity reflects interaction between genes and environment
present/past eating and activity patterns influence current body weight
food availability in environment
- ex. buffet, abundance of high-caloric and fatty foods
- serving size increases over the years

Physical Inactivity

life requires little exertion (modern conveniences)
sedentary lifestyle → weight gain
DRI prevents weight gain
- 60 mins of moderately intense daily activity
- weight loss encourages greater duration, intensity, and frequency of activity

Health Risks

body weight indicates heath related risk factors
- BMI >25
- waist circumference >40 in. for men and >35 in. for women

Treatments for Obesity

Dangerous Interventions

diet books/programs → little success maintaining weight-loss
fad diets → eating plans that promise quick weight loss
weight-loss products → dietary supplements don’t require FDA approval
- not effective and many proved harmful

Drug Treatment for Obesity

strategies for weight loss depend on degree of obesity and risk of disease
drug use for long-term weight loss program:
- for people with medical risks
- assist with modest weight loss
FDA approval → mandate states benefits must outweigh risks

New Obesity Guidelines

5 recommendation’s:

identify patients needing weight loss → counseling about benefits of weight loss → dietary therapy for weight loss → lifestyle intervention/counseling → bariatric surgery

Surgical Treatments for Obesity

~200,000 surgeries performed annually in US for clinically severe obesity
- clinically severe obesity → BMI > 40
reduces food capacity of stomach → limiting intake
gastric bypass changes hormone production
long-term safety/effectiveness emphasized prior to surgery

Weight Loss Strategies

Benefits to Weight Loss Strategies

characteristics of successful strategies:

embrace changes
celebrate losses
goals st
psychosocial support
incorporation of healthy eating and physical activity

reasonable weight loss rate → 0.5 - 2.0 lb. per week

Eating Patters

be realistic about energy intake
- avoid restrictive eating/rapid weight loss
goal → nutritional adequacy without excess
- deficit → 500 -1000 kcal per day
breakfast frequency → inversely related to obesity

Eating to Lose Weight

nutritional adequacy
- minimum 1200 kcal per day
eating smaller portions
- eat less food each meal
- satisfied, not stuffed
eating habits
- prepare meal plans
- slow down
- reduce energy density
- hydration
focus on fiber
- low energy, high nutrients
choose fat sensibly
- energy dense and satiation
select carbohydrates carefully
- whole, not processed
watch empty kcal
- fat, sugar, alcohol

Physical Activity

best approach to weight management → moderate physical activity + daily activities
combination of diet and exercise
- lose more fat
- retain muscle
- regain less weight

Activity and Energy Expenditure

kcal expenditure → influenced by body weight, intensity, and duration
greater energy deficit → greater weight loss
metabolism speeds up with activity

Physical Benefits of Activity

body composition
- fat decreases with increased total expenditure
- lean body mass increases with strength-training
appetite control
- physical activity may delay appetite

Psychological Benefits of Activity

self-esteem
choosing activities you enjoy regularly
moderate intensity → 2000 kcal burnt per week