Nutrition Chapter 15: Weight Management

Chapter 15: Weight Management

• Weight management is crucial for maintaining overall health and well-being.

• Maintaining a healthy weight range (BMI 18.5–24.9) reduces the risk of weight-related health issues and chronic diseases.

Learning Outcomes

• Explain why weight management is important for health and well-being.
• Define appetite, hunger, and satiety, and describe physiological factors for regulating food intake.
• Describe how hyperplasia and hypertrophy of adipocytes contribute to obesity.
• Discuss the interplay of genetics and environment in underweight, overweight, and obesity.
• Describe the role of diet and exercise in achieving a reasonable weight loss rate.
• Design a food and exercise plan to maintain a healthy weight.
• Describe the role of diet and exercise in achieving a healthy weight gain.
• Describe the role of weight-loss drugs and surgery for reducing obesity.

Prevalence of Overweight and Obesity (2017-2018)

• Adults:

  • Obesity (≥20 years): 42.5%
  • Overweight, including obesity (≥20 years): 73.6%

• Adolescents and Children:

  • Obesity (12-19 years): 21.2%
  • Obesity (6-11 years): 20.3%
  • Obesity (2-5 years): 13.4%

• Note: Statistics may be outdated.

Status of Obesity in America

• Americans spend more than $60 billion annually on weight-loss solutions.
• The US healthcare system spends $190 billion annually on obesity-related medical conditions.

Why Weight Management Is Important?

• Weight management involves maintaining body weight within a healthy range (BMI 18.5-24.9).

• Healthy weight means a body weight that doesn't increase risk of weight-related health issues and diseases.

• Healthy weight lowers risk for chronic diseases.

The AMA Considers Obesity a Disease

• In 2013, the AMA declared obesity a disease.

• Obesity is a multi-metabolic and hormonal disease state.

• Benefits of the designation:

  • Potential shift in physician approaches to obesity management (e.g., drug therapies, surgery)
  • Potential increased insurance coverage and accessibility of treatment for obesity.
  • Increased research funding to address obesity.

• Potential downsides:

  • Potential increased use of medications and procedures instead of lifestyle changes.

Problems Associated With Being Obese

• Hypertension
• Heart disease
• Stroke
• Elevated lipid levels
• Low HDL cholesterol
• Insulin resistance
• Certain cancers
• Pregnancy complications
• Surgical procedure complications
• Decreased quality of life and longevity
• Depression
• Reproductive problems
• Gallbladder disease
• Joint stress/osteoarthritis
• Sleep apnea
• Metabolic syndrome

Overweight and Social and Psychological Risks

• Overweight individuals face discrimination.

• They are less likely to get promotions or raises.

• Can be perceived as lazy or weak-willed by others.

• People who are overweight or obese may be less likely to exercise.

• Obese individuals experience higher rates of suicide and have a higher likelihood of drug/alcohol abuse.

Problems Associated With Being Underweight

• Anemia
• Heart irregularities
• Amenorrhea (loss of menstruation in women)
• At risk for low body protein and fat stores, and depressed immune system. This means difficulty fighting infections.
• Lack of vital nutrients
• Osteoporosis
• Infertility

Underweight and Social and Psychological Risks

• Underweight individuals experience increased irritability, anger, and depression.

• Underweight males are at a greater risk for committing suicide.

• Underweight individuals may be socially withdrawn

How Is Food Intake Regulated?

• Appetite: Desire to eat, influenced by psychological factors (time of day, social events, emotions, sight/smell of food).

• Hunger: Physical sensation associated with the need for food (physiological).

• Satiety: Feeling of fullness triggered by food consumption (physiological).

• Hormones in brain and gastrointestinal tract regulate hunger and satiety.

The Brain Controls Hunger and Satiation

• Two brain regions involved include:

  • Ventromedial nucleus
  • Lateral hypothalamus

• These help control eating behaviors based on hormone release from the:

  • Stomach
  • Pancreas
  • Small intestine
  • Adipocytes
  • Hypothalamus

How Is Food Intake Regulated?: Satiety

• Satiety: Triggered by the ventromedial nucleus.
  • Cholecystokinin (CKK)
  • Peptide YY (PYY) Secreted by the small intestine to stimulate satiety.
  • Leptin: Produced in adipose tissue, decreases hunger, regulates fat storage, and increases with fat storage. -Certain macronutrients (especially protein) promote satiety and reduce food intake

Leptin

• Leptin production is controlled by the obese gene (ob).
• Mice with a defective obese gene fail to produce leptin and gain weight.

How Is Food Intake Regulated?: Hunger

• Hunger: Controlled by the lateral hypothalamus.

  • Ghrelin: Secreted by the stomach, increased production signals the hypothalamus that the body needs energy, stimulating hunger.

  • Increased when blood sugar is low (before a meal, between meals, during sleep, and periods of fasting).

  • Lean individuals have higher ghrelin levels.

  • Neuropeptide Y (NPY): Produced in the hypothalamus and activated by ghrelin; stimulates hunger.

• Leptin: (partly responsible)

  • Leptin decreases when adipocytes shrink, stimulating hunger.

How Do Fat Cells Form and Expand?

• Fat cell growth (adipocytes) happens through two mechanisms:
  • Hypertrophy: Fat cells expand in capacity to store more fat.
  • Hyperplasia: Once filled, fat cells stimulate the production of more fat cells.

The Number of Fat Cells in the Body

• Average adult has 30-50 billion adipocytes.

• Overweight/obese adults have larger adipocytes.

• Adipocyte size decreases with weight loss but, the number of cells doesn't decrease.

• Fat cells can be filled again, and growth continues throughout life, though hyperplasia slows with age.

Fat Cells Can Grow and Shrink

• Enzymes control fat cell size.
  • Lipoprotein lipase (LPL) increases fat storage (lipogenesis).
  • Hormone-sensitive lipase (HSL) stimulates fat breakdown (lipolysis).
• Heavier people have increased LPL activity.
• Men: LPL more active in visceral/abdominal fat.
• Women: LPL more active in hips and thighs

How Do Genetics and Environment Influence Obesity and Weight Management?

• Nutrigenomics: The way genetic makeup interacts with nutrients for absorption, storage, and digestion.

• Epigenetics: Changes in gene activity and expression without changing the DNA sequence.

  • Food is an epigenetic factor that can cause DNA-histones to unwind and expose inactive genes. -While genetic makeup can't be changed, factors that control obesity genes can be controlled.

Personalized or Precision Nutrition

• Concept of adapting food to individual needs.
• Consumers respond differently to diets based on genetic makeup, lifestyle, and environmental factors.
• Customizing nutrition advice can motivate individuals to make dietary changes to reduce obesity and related diseases like type 2 diabetes and heart disease.

Genetics Can Influence Hunger, Satiety, and Insulin Response

• Altered genes can influence individual's hormonal response to food, affecting hunger and satiety.

• Single-nucleotide polymorphisms (SNPs) can alter gene activity.

• Epigenetic modifications influence how people respond to food intake.

Genetics Can Influence Hunger, Satiety, and Insulin Response (continued)

• Adipocytes secrete adiponectin;
  • Improves body's insulin response, reduces fat buildup in liver and muscles, and enhances energy expenditure.
  • Lower in obese/type-2 diabetes compared to lean people.
• Genetics can affect thermogenesis (energy expenditure).

Genetics Can Influence Hunger, Satiety, and Insulin Response (continued)

• Genetic "set point" theory: Theory of weight control suggesting body attempts to stay at a specific weight.
• Thrifty genes: Enable individuals to efficiently store fat, potentially aiding in survival during periods of food scarcity.

Genetics Can Influence Hunger, Satiety, and Insulin Response (continued)

• Genetically predisposed individuals to be overweight/obese can still achieve healthy weight through regular exercise and diet.

Environmental Factors Can Increase Appetite and Decrease Physical Activity

• Current environment makes positive energy balances (weight gain) easier.
• Environmental factors related to obesity:
• Lack of time
  • Eating meals out of home often leads to higher BMI and less fruit/vegetable consumption.
  • Abundance of food/easy access.
  • Larger portions lead to increased consumption.
  • Reduced physical activity, such as decreased manual labor, increased reliance on driving or spending more time in front of TV or computer

How Can You Lose Weight Healthfully?

• Avoid fad diets and strive for gradual weight loss (10% over six months).

• Modify diet, physical activity & behavior.

• Choose lower kilocalorie foods and reduce portion sizes.

• Increase physical activity duration (60–90 minutes per day of moderate intensity).

• Incorporate cardiorespiratory and strength training.

• Employ behavior modification (food logging), manage stress, and control environmental triggers for eating

How Can Weight Loss Be Maintained?

• Maintain energy-gap reduction (decrease calorie intake and increase calorie expenditure).

• Reduce portions and fatty foods.

• Eat smaller, more frequent meals (avoid grazing).

• Maintain high physical activity.

• Weekly self-weighing can help maintain weight loss.

What Is the Healthiest Way to Gain Weight?

• Gaining weight is challenging for underweight individuals.

• The goal is to gain muscle, not fat.

• Increase daily calorie intake by 500 calories.

• Choose energy-dense foods.

• Include regular exercise and resistance training.

What Are the Medical Interventions for Extreme Obesity?

• Weight-loss medications:
  • Sibutramine (Meridia): Hunger suppressant.
  • Orlistat (Xenical): Inhibits fat absorption.
  • Liraglutide (Saxenda): Stimulates satiety hormone release.
• Evaluate side effects of medications before deciding if they are worthwhile.

Weight Loss Surgeries

• Gastric bypass: Most common procedure; allows food to bypass part of the small intestine.
• Gastric banding: Reduces the stomach size with adjustable silicone band.
• Sleeve gastrectomy: Part of the stomach is removed.

Bariatric Surgery Restricts Food Intake

• Post-surgery considerations:
  • Consume small, frequent meals.
  • Supplement with iron, calcium, vitamin B12, and vitamin C.
  • Weight loss: 5–15 lbs/week initially, then 1–2 lbs/week.
• Surgical benefits: -Reduction in diabetes (76.8%), improved lipid profiles (70.0%), elimination of hypertension (61.7%), and elimination of sleep apnea.

This quiz covers the key concepts of weight management and its importance for overall health. You will explore factors influencing appetite, the impact of genetics and environment on body weight, and the roles of diet and exercise in achieving healthy weight outcomes. Test your knowledge on maintaining a healthy weight range and the interventions available for obesity management.