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10. Epidemiology of obesity

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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