Weight Management exam 3

Weight Management: Overweight, Obesity, and Underweight

Learning Objectives

• Describe how body fat develops and why maintaining weight gains and losses can be difficult.

• Review causes of obesity.

• Discuss physical, social, and psychological consequences of overweight and obesity.

• Explain risks and benefits of aggressive obesity treatments.

• Outline strategies for achieving and maintaining healthy body weight.

• Summarize strategies for gaining weight.

Estimated Energy Requirement (EER)

Definition and Calculation

The Estimated Energy Requirement (EER) is the amount of daily energy needed to maintain a healthy body weight and meet energy (calorie) needs, based on age, gender, height, weight, and activity level.

• EER is calculated using predictive equations that factor in these variables.

• Formula example: $EER = Basal~Metabolic~Rate~(BMR) + Physical~Activity~+~Thermic~Effect~of~Food$

Energy Imbalance

Consequences of Caloric Imbalance

• Too few calories can cause underweight:

  • Stored glycogen and fat are used as fuel sources.

  • Protein breakdown from body tissues can be used to make glucose.

  • Prolonged deficiency leads to loss of lean tissue and can be fatal.

• Too many calories can cause overweight:

  • Excess calories are stored as fat, regardless of source.

  • Body has unlimited capacity to store fat.

  • Body contains about 35 billion fat cells, which can expand.

Overweight and Obesity Comparisons

Prevalence and Trends

• 75% of adults in the US are either overweight or obese.

• Obesity rates are increasing across all ages, races, and educational levels.

• Growing concern worldwide, including children and adolescents.

Fat Cell Development and Metabolism

Fat Cell Development

• Fat cells can increase their size by 20-fold and their number by several thousandfold.

• During growth, fat cells increase in number; with excess energy, they increase in size.

Fat Cell Metabolism

• Lipoprotein lipase (LPL) hydrolyzes triglycerides in the bloodstream and directs their parts into the cell.

• LPL activity is influenced by gender (higher in women’s hips/thighs, men’s abdomen).

• Enzyme activity may explain why weight regain is common after weight loss.

Factors Affecting Body Weight

Major Influences

• What and how often you eat

• Physiology

• Genetics

• Environment

Hunger and Appetite

Definitions and Influences

• Appetite: Psychological desire for food.

• Hunger: Physiological need for food; subsides as satiety sets in.

• Appetite is affected by environmental factors (sight/smell of food, social setting, stress).

Physiological Mechanisms Regulating Hunger

Hormonal Regulation

• Ghrelin: Produced in stomach when empty; increases hunger.

• Leptin: Produced in fat tissue; signals brain to decrease hunger and food intake.

• Cholecystokinin: Released when stomach is distended; increases satiety.

• Protein, fatty acids, and monosaccharides stimulate feedback to decrease hunger.

• Insulin also decreases hunger.

Ghrelin and Leptin

Roles in Weight Regulation

• Ghrelin ("hunger hormone"): Increases appetite, promotes positive energy balance.

• Leptin: Suppresses appetite, increases energy expenditure, promotes negative energy balance.

• Leptin injections can reduce body weight in animals and humans.

• Genetic deficiency or receptor mutation can lead to weight gain.

Genetics and Body Weight

Genetic Influences

• Obesity risk doubles if parents are overweight, triples if obese, five times greater if severely obese.

• Confirmed by studies of identical twins separated at birth.

• Obesity reflects gene-environment interaction.

• Genetic differences in hormone levels (ghrelin, leptin) and nonexercise-associated thermogenesis (NEAT) affect weight.

• Set point theory: Body opposes weight loss and works to maintain a set weight.

Gene-Environment Interaction

Environmental Factors

• Cheap, energy-dense foods stimulate appetite.

• Decreased physical activity due to labor-saving devices and sedentary leisure.

• Frequent dining out associated with higher BMI.

Environmental Factors

Impact on Weight

• Increased availability of food-service establishments and larger portions encourage overeating.

• Americans eat about 300+ calories/day more than in 1985.

• To prevent weight gain, strive for 60 minutes of moderately intense activity daily.

Healthy Weight Loss Strategies

Recommended Approaches

• NIH recommends losing about 10% of body weight over 6 months.

• To lose 1 pound of body fat, need a 3,500 calorie deficit.

• Decrease daily calories by 250 to 500 for weight loss of ½ to 1 lb/week.

Long-Term Weight Loss

• Requires changes in diet, physical activity, and behavior.

• Eat more vegetables, fruit, and fiber; protein increases satiety most.

• Fat slows movement of food from stomach to intestines.

• Choose lean meats, skinless chicken, fish, nuts, and unsaturated oils.

Three Pieces of the Long-Term Weight Loss Puzzle

• Healthy eating

• Physical activity

• Behavior modification

Adding Volume to Meals

Low vs. High Volume Meals

Low-Volume, High-Calorie	High-Volume, Low-Calorie
Chicken broth + bread (347-476 kcal)	Chicken broth + vegetables (300-324 kcal)

Energy Density of Foods

Energy Density	Description	Examples
Low	0.7-1.5 kcal/g, high in water/fiber	Vegetables, fruits, soups
Medium	1.5-4 kcal/g, less water	Breads, bagels, meats
High	4-9 kcal/g, low water, high fat/sugar	Cookies, chips, nuts

Volume of Food You Eat

Low-Volume, High-Calorie	High-Volume, Low-Calorie
Coffee + donut (460 kcal), pizza (890 kcal)	Popcorn (180 kcal), veggie pizza (676 kcal)

Behavior Modification and Attitude

Strategies for Success

• Set small, time-specific goals (SMART goals).

• Practice and reward positive behaviors.

• Keep records (food logs).

Extreme Measures for Extreme Obesity

Medical Interventions

• BMI > 40 is considered extreme obesity.

• High risk of heart disease, stroke, and death.

• Requires aggressive treatment: very-low-calorie diets, medications, and/or surgery.

• Very-low-calorie diets (<800 kcal) must be medically supervised.

• Medications (e.g., Orlistat) cannot replace healthy diet and activity.

Surgical Interventions

• Gastric bypass and gastric banding increase satiety and reduce hunger.

• Risks include ulcers, gallstones, bleeding, and nutrient deficiencies.

• Liposuction is cosmetic and does not improve health outcomes.

Healthy Weight Gain Strategies

For Underweight Individuals

• Add at least 500 calories/day for gain of 1 pound/week.

• Choose energy-dense but nutritious foods from all food groups.

• Eat more snacks and exercise to build muscle.

Problems of Underweight

• Diverse causes: high energy demand, growth, development.

• Adaptive thermogenesis makes weight gain difficult.

• Difference between underweight and anorexia nervosa.

Disordered Eating and Eating Disorders

Definitions

• Disordered eating: Abnormal, potentially harmful eating behaviors not meeting criteria for eating disorders.

• Eating disorders: Psychological illnesses involving specific abnormal eating behaviors.

• About 11 million in the US struggle with eating disorders.

Causes

• Sociocultural, genetic, and psychological factors.

Diagnostic Criteria for Eating Disorders

Eating Disorder	Diagnostic Criteria
Anorexia nervosa	Refusal to maintain normal weight, intense fear of gaining weight, distorted body image, loss of menstrual period
Bulimia nervosa	Recurrent binge eating, compensatory behaviors (vomiting, fasting, excessive exercise), self-evaluation unduly influenced by body shape/weight
Binge eating disorder	Recurrent episodes of binge eating without compensatory behaviors

Anorexia Nervosa & Bulimia Nervosa

Characteristics and Health Consequences

• Anorexia nervosa: Severe calorie restriction, self-starvation, intense fear of being "fat", distorted body image, health risks (electrolyte imbalance, low blood pressure, osteoporosis).

• Bulimia nervosa: Cycles of binge eating and purging, health risks (electrolyte imbalance, dental erosion, gastrointestinal issues).

Other Eating Disorders

Binge Eating Disorder & Night Eating Syndrome

• Binge eating disorder: Compulsive overeating without purging, associated with obesity.

• Night eating syndrome: Eating, sleeping, and mood disorder; majority of calories consumed after evening meal.

Warning Signs for Eating Disorders

Symptom	Explanation/Example
Weight below 85% of expected	Refusal to accept/maintain healthy weight
Excessive exercise	Compulsively worried about weight loss
Distorted body image	Sees self as fat when underweight
Loss of menstrual period	Predicts hormonal imbalance
Avoid eating with others	Makes excuses to avoid eating

Treatment of Eating Disorders

Multidisciplinary Approach

• Psychological, medical, and nutrition professionals work together.

• Nutritional approaches: Identify triggers, ensure adequate calories/nutrients, use food journals.

• Recovery is slow; greater success if treated early.

Quiz Yourself!

• What percent of US adults are underweight? 2 percent

• Health risk indicators: All of the above (BMI, waist circumference, disease risk profile, family history)

• Fat is stored in adipose tissue.

• Number and size of fat cells increase with positive energy balance.