Obesity Trends and Metabolism Overview

Obesity Prevalence

• Worldwide, 1.9 billion adults and 41 million children under five are affected by obesity.
• In Saudi Arabia (2018), 24.1% of men and 33.5% of women were obese.
• Rising obesity rates are linked to a global food system that promotes energy-dense, processed, and affordable foods.

Childhood Obesity in Saudi Arabia

• In 2012, 15% of children under five were overweight and 6% were obese.
• For children five years and older, those figures were 23% overweight and 9.3% obese.

BMI and Overweight

• A BMI exceeding 25 indicates overweight.

Fat Cells

• Fat is stored in adipose tissue.
• Fat cell size and number increase with positive energy balance.
• Increased fat cell size triggers cell proliferation.
• Fat cell number remains constant during negative energy balance.
• People with extra fat cells easily regain weight.
• Ectopic fat (fat outside adipose tissue) disrupts normal metabolism, contributing to disease.

Fat Cell Metabolism

• Lipoprotein lipase (LPL) removes triglycerides from blood for storage in adipose tissue and muscle cells.
• Obese people have higher LPL activity in fat cells, making fat storage more efficient.
• This leads to a more dramatic impact of modest energy excesses on obese individuals compared to lean people.
• Women have higher LPL levels in breasts, thighs, and hips.
• Men have higher LPL levels in abdominal fat cells.
• After weight loss, LPL activity in adipose tissue increases, contributing to weight regain.

Types of Fat

• White adipose tissue stores fat for energy use by other cells.
• Brown adipose tissue releases stored energy as heat, defending against cold and preventing obesity.
  • Important in newborns and cold-exposed animals.
  • Brown fat activity declines with age and obesity.
• Brite adipocytes (beige adipocytes) are white fat cells with brown fat characteristics.
  • Contain active uncoupling proteins.
  • More abundant than brown fat cells in adults.
  • Physical activity triggers browning (transformation of white fat cells into brite fat cells).

Set-Point Theory

• After weight loss, the body adjusts its metabolism to favor weight regain.
• This decrease in metabolic rate is greater than expected based on body composition alone.

Causes of Overweight and Obesity

• Genetics and Epigenetics:
  • Genes influence energy balance and satiety pathways.
  • Environmental factors like diet and activity affect gene expression.
  • Epigenetics can influence gene expression without changing the genome.
  • Genetics may determine a person's susceptibility to obesity.

Obesity Gene (ob)

• Expressed primarily in adipose tissue.
• Codes for leptin (satiety hormone).
  • Acts on the hypothalamus.
  • Promotes negative energy balance and weight reduction.
  • Suppresses appetite and increases energy expenditure.
  • Leptin levels increase with body fat.
  • Leptin sensitivity decreases (leptin resistance).
  • Leptin injections reduce body weight in animals and humans.
• Rare genetic deficiency of leptin or receptor mutation in humans.

Ghrelin

• Hormone secreted by stomach cells.
• Hunger hormone.
• Acts on the hypothalamus.
• Increases appetite.
• Promotes positive energy balance and weight gain.
• Influenced by psychological mindset and sleep:
  • Lack of sleep increases ghrelin and decreases leptin.

Environmental Factors

• Obesogenic environments: daily circumstances that promote fatness.
• Overeating:
  • Past and present eating and activity patterns influence weight.
  • Food availability and portion sizes play a role.
  • Restaurant food often features large portions.
• Physical Inactivity:
  • Modern technology has replaced physical activity.
  • Sedentary activities require little energy and replace time for more vigorous activities.
  • Watching television is linked to increased food purchases and snacking on unhealthy foods.
  • People need physical activity to consume enough nutrients without weight gain.
  • The DRI suggests 60 minutes of moderate-intensity physical activity daily, in addition to daily living activities, to prevent weight gain.

Consequences of Obesity

• Social consequences:
  • Discrimination in jobs, school, and social situations.
  • Judged by appearance over character.
  • Negative stereotypes, such as laziness and lack of self-control.
  • Discrimination may worsen overeating.
• Psychological problems:
  • Embarrassment, rejection, shame, and depression.

Health Risks

• Weight loss is recommended for obese individuals (BMI ≥ 30) and overweight people (BMI 25-29.9) with:
  • Hypertension
  • Fatty liver disease
  • Abnormal blood lipids
  • Diabetes or prediabetes
  • Sleep apnea

Dangerous Weight-Loss Interventions

• Diet books and weight-loss programs:
  • Often ineffective and rely on deceptive claims and testimonials.
• Fad diets:
  • Popular plans promising quick weight loss, severely limiting certain foods or overemphasizing others.
  • Examples include avoiding potatoes or pasta, or consuming cabbage soup daily.
• Weight-loss products:
  • Herbal and dietary supplements:
    • Safety and effectiveness cannot be assumed.
    • Do not require FDA approval.
    • Often contain undeclared ingredients.
    • Can have serious consequences like seizures and heart attacks.
• Other gimmicks:
  • Hot baths to speed up metabolism can lead to dehydration.

Weight-Loss Strategies

• Successful treatment combines:
  • Healthy eating, physical activity, supportive environment, and psychosocial support as first-line therapy.
• Reasonable rate of weight loss:
  • 0.25 to 1 kg/week.
  • 5 to 10 percent of body weight over 6 months.
    • More sustainable than rapid weight loss.
    • Modest losses improve disease-related factors, such as blood glucose, blood pressure, and lipids.
  • Daily balanced eating and activity are crucial.

Eating Patterns

• No single food plan is magical.
• Consistency in eating is essential for successful weight maintenance.
• Preventing weight gain is easier than losing weight.
• Both weight loss and prevention involve similar strategies.
• A major difference is the focus on developing beneficial eating and activity habits early in life to prevent unhealthy habits.

Benefits of Physical Activity

• Exercise changes body composition, decreasing fat mass and increasing lean mass, even without weight loss.
• Exercise suppresses appetite, inhibiting inappropriate appetite driven by boredom or anxiety.

Behavior and Attitude

• Behavior modification:
  • Adopt a positive and proactive attitude.
  • Incorporate healthy eating and activity into daily routines.
• Becoming aware of behaviors:
  • Keep a record of behaviors.
• Changing behaviors:
  • Avoid shopping for food when hungry.
  • Avoid eating while watching television.

Cognitive Skills

• Successful behavior change depends on:
  • Problem-solving and cognitive restructuring to replace negative thoughts.
  • Other health behaviors.
• Personal attitude:
  • Understand the personal relationship with food.
  • Identify triggers for overeating.
  • Problem-solve to change responses to triggers.
• Support groups:
  • Seek support from others.

Drug Treatment for Obesity

• Strategies vary based on obesity level and disease risk.
• Drugs can contribute to weight loss as part of a comprehensive, long-term plan.
• FDA approval criteria: Benefits must clearly outweigh the risks.
• Orlistat (Xenical):
  • Inhibits pancreatic lipase in the GI tract, blocking fat digestion and absorption for reduced energy intake.
  • Side effects: GI cramping, diarrhea, gas, frequent bowel movements, reduced fat-soluble vitamin absorption, rare cases of liver injury.

Surgical Treatments for Obesity

• Surgery may be considered for individuals who:

  • Cannot lose weight through diet and exercise.
  • Have a BMI ≥ 40 or ≥ 35 with obesity-related health problems like diabetes or hypertension.
  • Have no contraindications (medical or psychological).
  • Understand the risks and are committed to post-surgery treatment.

• Surgeries reduce stomach size, limiting food intake.