Lecture 12

• Many of the 20 leading risk factors for disease are related to nutritional disorders
• Global syndemic includes obesity, undernutrition, and climate change
• Traditional risks of death have decreased (undernutrition, water sanitation and hygiene)
• Modern risks of death have increased (tobacco, overweight/physical inactivity, air quality)
• The Big food industry is compared to the new Big tobacco
• Approximately 1 billion people are undernourished
• Undernourishment categories:

  • Normal
  • Wasting: low weight for height
  • Stunting: low height for age due to poor nutrition
  • Underweight: low weight for age
  • Overweight/obesity: high weight for height
  • Double burden: experiencing both stunting and overweight
• Severe acute malnutrition is a form of undernutrition
• Starvation effects:

  • Cardiac changes
  • Disorders in water balance
  • Nutrition deficiencies
  • Loss of fat, muscle, hair, and bone (brain initially protected)
  • Mainly uses fat sources as energy
  • Resting metabolic rate increases with trauma, but decreases in starvation to prolong life
  • Adaptive changes in metabolism decrease Na/K pump, temperature homeostasis, fertility, inflammatory and immune response
  • Stunting is seen as an adaptation to prolong life
  • Vitamin deficiency often accompanies undernutrition, leading to conditions like rickets where dietary calcium is absorbed from bones
• Primary undernutrition is caused by insufficient food or famine
• Secondary undernutrition can result from malabsorption, cancer, or drug abuse
• Anorexia Nervosa:

  • Tends to occur during late childhood and early adolescence
  • Serious eating disorder involving starvation
  • Distorted body image
  • Refusal to maintain minimally normal weight
  • Pathological fear of gaining weight
• Bulimia Nervosa:

  • Involves vomiting
  • Jockeys for horse races aim to be lighter for speed
  • Changes include alkalosis, loss of K/Na/Cl, gastric rupture, aspiration pneumonia, cardiac arrest due to electrolyte imbalance, and enamel loss on teeth due to acid damage
• Modelling and ballet schools are professions where eating disorders are prevalent
• With time and social pressure, individuals may starve and exercise excessively, leading to altered neurochemistry in the brain and up to 20% mortality with long-term consequences like osteoporosis
• Gut microbiota contributes to the pathogenesis of anorexia nervosa
• Therapy, including hospitalization and tube feeding, is sometimes necessary for treatment
• Bone loss can persist even after treatment, making individuals vulnerable to fractures
• Overnutrition:

  • Most years of life lost are due to obesity, especially when it starts at a young age
  • Risks include hypertension, cancer, gallbladder disease, renal failure, stroke, heart failure, and atherosclerosis
• Obesity is defined as a BMI over 30, with overweight being a BMI over 25
• Weight problems tend to increase with age
• Obesity is not the same for everyone and can have varying medical complications
• Causes and risks of obesity include genetic factors having minimal effects, with lifestyle, environment, and culture playing significant roles
• Energy imbalance is a key factor in obesity, with food intake exceeding energy expenditure/physical activity
• Adipocytes:

  • Differentiate from stem cells and accumulate lipids
  • Hypertrophy when gaining weight and can lead to hyperplasia
  • Release signaling molecules that increase the risk of diabetes and inflammation
• Adipose tissue releases leptin and adiponectin, which play roles in regulating eating habits and energy balance
• Adipocyte location affects health risks, with visceral fat being more dangerous than subcutaneous fat
• Types of adipose tissue include pink, visceral white, brown, and subcutaneous white, each serving different functions
• Chemotactic adipokines recruit monocyte macrophages, leading to an inflammatory response in regions with adipocytes
• Obesity is linked to an increase in plasma triglycerides, glucose, and insulin, causing Hyperlipidemia, hyperinsulinemia, and hyperglycemia (risks for cardiovascular diseases, stroke, and type 2 diabetes)
• Exercise and a balanced diet can help reduce inflammation and minimize liver and cardiovascular problems associated with obesity
• Obesity is a result of an energy imbalance between food intake/storage and energy expenditure, with cultural factors influencing dietary habits
• overnutrition is due to lack of exercise and consumption of high fat/calorie foods
• what is BMI? and what is the optimal range?

  weight (kg)/height(m2) and 21-25
• Increasing death rate with increasing BMI.
• what is the normal percent body fat?

  20%
• how can you measure subcutaneous fat?

  can measure skinfold thickness by calipers
• Intraabdominal fat is more dangerous
• Categories of overnutrition:

  • Category 1 overweight: BMI 25-30
  • Category 2 overweight: BMI 30-40
  • Category 3 morbid obesity: BMI >50
• what are medical complication of obesity?

  • Stroke, CHD, cancer, pulmonary disease, etc.
  • Risk of diabetes goes up.
  • Kills many people due to cardiovascular disease and cancer (breast, prostate, colon, uterus, cervix, kidney)