10. Epidemiology of obesity

Obesity

• Epidemiology
  • Worldwide obesity has more than doubled since 1980
  • In 2014 more than 1.9 billion (39%) adults were overweight. 600 million (13%) were obese
  • North Africa, the Middle East and Latin America are almost as overweight as Europe
  • Obesity is growing in the developing world. Here the number of overweight adults has more than tripled since 1980
  • In Europe
    • Romania, Italy least obese
    • Hungary, Great Britain most obese
• Definition of obesity – according to WHO
  • BMI 25 – 30 – overweight (pre-obese)
  • BMI 30 – 35 – Obese (type I obesity)
  • BMI 35 – 40 – Severely obese (type II obesity)
  • BMI > 40 – Morbidly obese (type III obesity)
  • Other tools in measurement of obesity:
    • Hip-waist ratio
    • Skinfold thickness
    • Waist and hip circumference
  • Types of obesity
    • Hyperplastic obesity – number of adipocytes is increased
      • Often seen in prepubertal obese people and people who have been obese since a young age
      • Often peripheral obesity
    • Hypertrophic obesity – adipocytes are hypertrophic
      • Often seen in people who become obese in adulthood
      • Often central obesity
      • Male type (“android”)
        • Associated with cardiovascular disease, cancer
      • Female type (“gynoid”)
        • Associated with varicose veins, thrombosis

Android and gynoid types of obesity

• Central obesity
  • Chronic inflammatory state
  • Insulin resistance
  • Dyslipidaemia
  • Diabetes mellitus type 2
• Causes of obesity
  • All cases of obesity are due to excessive energy intake compared to energy expenditure
  • Genetic factors
    • GLUT4
    • IRS-1
    • Adiponectin
    • Leptin
    • Genetic differences in metabolic rate
    • Genetic differences in the reward of eating
  • Excessive energy intake
  • Physical inactivity
  • Pregnancy
  • Secondary obesity
    • Certain drugs
    • Hormonal imbalance
      • Cushing syndrome
      • Polycystic ovary syndrome
• Consequences of obesity
  • Increased mortality
  • Increased risk for diabetes mellitus type 2
  • Obstructive sleep apnoea
  • Metabolic syndrome
  • Cardiovascular disease
  • Arthritis
  • Cancer
    • Breast cancer
      • Only postmenopausal
      • Excess amount of oestrogen produced by adipose tissue
    • Colorectal cancer
    • Oesophageal cancer
    • Endometrium
      • Excess oestrogen
    • Pancreas
    • Renal cell cancer
  • Mechanism of cancer development
    • Increased level of hormones who stimulate cell proliferation
      • Insulin
      • Insulin-like growth factor
      • Leptin
    • Chronic inflammation
    • Oxidative stress
    • Activation of NF-κB
    • Excess amount of oestrogen

Obesity in childhood

• Tripled in last 30 years
• Lifelong lifestyle habits are established during childhood
• Much study time, television -> mild obesity -> too tired for sports or activity -> moderate obesity -> bullying causes obese child to eat comfort foods -> severe obesity