Weight Management

Université d'Ottawa: HSS 1101 - Determinants of Health

Chapter 4: Weight Management

  • Slides prepared by Dave Kato, MacEwan University

  • Based on CORE CONCEPTS IN HEALTH by Irwin Burke, Insel, Roth, and Insel, Fourth Canadian Edition.

The Prevalence of Adult Obesity in Canada

  • Figure 4.1: Illustrates the prevalence of adult obesity (18+) in Canada by province, comparing self-reports versus measured heights and weights for the years 2004, 2005, and 2015.

Body Composition and Energy Balance

  • Body Composition: The human body is categorized into:

    • Fat-free Mass: Includes all non-fat tissues such as water, glycogen, skeletal muscle, and connective tissues.

    • Types of Body Fat: Divided into subcutaneous fat and visceral fat.

  • Energy Balance:

    • Maintenance of Healthy Energy Balance:

    • More energy consumed than expended results in a positive energy balance.

    • Less energy consumed than expended results in a negative energy balance.

    • Factors influencing energy expenditure:

    • Decreased physical activity.

    • Increased sedentary activities, such as prolonged screen time and video gaming.

Evaluating Body Weight and Composition

  • Body Mass Index (BMI):

    • A measure based on the relationship between height and weight, easily calculated and utilized.

    • Often used alongside other metrics to assess health risk.

    • Limitations of BMI:

    • Does not differentiate between fat mass and fat-free mass.

    • Can be inaccurate for well-muscled or shorter individuals.

    • Not useful for tracking body composition changes.

Methods of Body Composition Analysis

  • Hydrostatic Weighing:

    • One of the most accurate methods to assess body composition.

    • Percentage of body fat can be estimated from body density, noting that muscle weighs more than fat.

  • Bod Pod:

    • Utilizes air instead of water for measuring body fat. Uses computerized sensors for air displacement measurements.

  • Circumference Measures:

    • Waist circumference and waist-to-hip ratio help in measuring abdominal obesity and predicting health risks.

    • Waist Circumference:

    • Measured between the top of the hip and the lowest rib at the level of the umbilicus.

    • Risk Indicators:

      • A waist circumference >40 in (102 cm) for men and >35 in (88 cm) for women indicates increased chronic disease risk.

      • A waist-to-hip ratio >0.94 for young men and >0.82 for young women indicates increased risk of heart disease and diabetes.

  • Bioelectrical Impedance:

    • Uses a harmless electrical current to assess body fat percentage based on the conductivity of fat-free mass versus fat tissue.

    • Calculated using a computer for accuracy.

  • Scanning Procedures:

    • Involves very accurate methods to determine body fat but requires sophisticated equipment.

    • Methods include: DEXA, CAT scans, and MRIs.

Health Risks of Excess Body Fat

  • Mortality Risk:

    • Increased mortality rates associated with obesity, raising concerns that current generations may face shorter life expectancies than their parents.

    • Statistic: 1 in 10 premature deaths is attributable to obesity.

  • Health Conditions Associated with Obesity:

    • Elevated cholesterol and triglyceride levels.

    • Impaired heart function, leading to cardiac vascular disease (CVD).

    • Other risks include hypertension, impaired immune function, gallbladder and kidney diseases, mental health disorders, pregnancy complications, and more.

Diabetes Mellitus

  • Strong association between obesity and diabetes.

  • Diabetes can lead to severe complications such as kidney failure, nerve damage, retinal damage, blindness, stroke, and heart attacks.

  • Most common form related to obesity is Type 2 Diabetes.

Fat Distribution and Health Implications

  • Fat accumulation varies between genders:

    • Men: Tend to store fat in the upper body (apple shape).

    • Women: Tend to store fat in the lower body (pear shape).

  • A weight loss of 5-10% can yield significant health benefits.

  • Waist circumference can indicate abdominal obesity, with >102 cm (40 in) for men and >88 cm (35 in) for women being markers for the risk of metabolic syndrome and related diseases.

Problems with Very Low Body Fat

  • Very low body fat (8-12% in women, 3-5% in men) can jeopardize wellness:

    • Linked to reproductive, circulatory, and immune disorders.

    • Risk of muscle wasting and extreme fatigue.

    • Connections to eating disorders and the female athlete triad.

  • Symptoms of extreme low body fat include decreased bone density and amenorrhea, among other health issues.

Body Mass Index (BMI) and Waist Circumference Classification

  • Table 4.2 presents various classifications of BMI and waist circumference, along with associated disease risks:

    • BMI Classifications:

    • Underweight: < 18.5

    • Normal: 18.5–24.9

    • Overweight: 25.0–29.9 (Increased Disease Risk)

    • Obesity Classes I (30.0–34.9) - III (40.0+)

      • Class I: High, Class II: Very High, Class III: Extremely High risk for men and women.

Metabolism

  • Metabolism: A critical factor in maintaining body weight and fat regulation.

    • Largest Component: Resting Metabolic Rate (RMR).

    • RMR accounts for 60-70% of daily energy expenditure.

    • Influences include heredity and behavior:

    • Males typically exhibit higher RMR due to increased muscle mass.

    • Changes in weight affect RMR:

    • Weight loss decreases RMR.

    • Weight gain increases RMR.

    • Importance of exercise for maintaining muscle mass and RMR.

Hormones and Body Fat Distribution

  • Hormones significantly influence body fat accumulation and distribution, especially in women through different life stages (puberty, pregnancy, menopause).

  • Key hormones:

    • Leptin: Signals the brain regarding fat store levels.

    • Ghrelin: Increases appetite and hunger.

    • Important Note: Hunger is not always the primary driving factor in food consumption.

Fat Cell Distribution

  • Figure 4.5: Illustrates the body's fat cell distribution, highlighting:

    • Visceral Fat: Associated with greater risk of metabolic syndrome.

    • Subcutaneous Fat: Generally has a lower associated health risk.

    • Common metaphor: "Apples are bad, and pears are good." (Refers to body shape and fat distribution).

Lifestyle Factors in Obesity

  • Obesity prevalence cannot be solely attributed to genetics but also lifestyle habits, including:

    • Overeating and consumption of high-calorie foods, low in essential nutrients.

    • Declining physical activity levels among Canadians leading to increased sedentary lifestyles.

    • Link between sleep deprivation and adverse effects on hormone levels, appetite regulation, and metabolism.

Obesogenic Environment

  • Describes an environment that encourages energy overconsumption and discourages physical activity.

    • Influential factors include:

    • Socioeconomic status, cultural norms, and geographic location.

    • The role of the food industry in promoting high-calorie processed foods via marketing strategies (fast food outlets, vending machines).

  • Government interventions: Example includes Ontario's requirement for calorie counts in food service establishments.

Psychosocial Factors Affecting Eating Behavior

  • Eating as a coping mechanism for emotions such as stress, loneliness, and low self-esteem can lead to disturbed eating patterns.

  • There is a strong correlation between obesity and socioeconomic status:

    • Obesity prevalence decreases with increased income; the trend varies by gender.

    • Cultural influences can make food a symbol of affection and part of sociocultural rituals.

Diet and Eating Habits

  • Diet: Refers to the sum of daily food choices made by individuals.

    • Attention should be given to:

    • Portion sizes and energy density of food consumed.

    • Incorporating moderate caloric restrictions alongside increased physical activity.

    • Foods low in energy density (high volume but low calorie) vs. high energy density foods.

Diet Books, Websites, and Social Media Programs

  • Many individuals attempt self-directed weight loss, often revolving around fad diets promoting quick results, generally through water loss.

  • Maintaining weight loss remains a significant challenge; dietary supplements and aids are typically poorly regulated.

Commercial Weight Loss Programs

  • Effective programs may offer group support, nutritional guidance, and behavior modification strategies.

  • Important aspects:

    • Programs should disclose all fees related to specialized foods and supplements.

    • Monitoring by a registered dietitian is recommended for effectiveness.

  • Example: Weight Watchers (WW) as a well-known program.

Severe Body Image Problems

  • Body Image: Comprises perceptions, thoughts, and feelings towards one’s body.

    • Negative body image leads to dissatisfaction and potential psychological issues, including disordered eating patterns.

    • Body Dysmorphic Disorder (BDD): Characterized by an extreme preoccupation with body appearance, leading to low self-esteem and the need for professional help.

Eating Disorders: Anorexia Nervosa

  • Anorexia Nervosa: A condition where individuals restrict food intake severely, often leading to unhealthy body weight levels.

    • Prevalence: Affects approximately 1% of the North American population (predominantly females).

    • Characteristics include:

    • Intense fear of gaining weight and compulsive behaviors to prevent eating.

Health Risks of Anorexia Nervosa

  • Associated health issues include cessation of menstruation, low blood pressure, cold intolerance, and severe bodily complications.

  • Potential for significant death risk from comorbid disorders and suicides.

Eating Disorders: Bulimia Nervosa

  • Bulimia Nervosa: Involves recurrent binge eating followed by purging behaviors; typically, individuals maintain a normal weight appearance.

    • Affects mainly females, characterized by a loss of control over eating.

Health Risks of Bulimia Nervosa

  • Risks include damage to teeth from stomach acid, potential liver and kidney harm, and association with mental health disorders.

Binge Eating Disorder

  • Approximately 2% of Canadians affected; characterized by uncontrollable eating, often accompanied by guilt.

    • Pattern includes rapid eating, and eating in response to distress rather than hunger.

Recognizing Eating Disorders

  • Indicators include obsessive thoughts about weight, feelings of guilt after eating, and unhealthy restrictive behaviors.

Treatment of Eating Disorders

  • Professional treatment is crucial to address the underlying issues of food misuse.

    • Anorexia treatment focuses on restoring healthy weight; bulimia treatment concentrates on stabilizing eating patterns.

    • Co-occurring mental health issues, such as depression, require integrated care.