Overweight and obesity are an abnormal or excessive fat accumulation that presents a risk to health. It is a risk factor
for many diseases and is linked to many deaths. Body mass index (BMI) is a simple index of weight-for-height used to classify overweight and obesity in adults.

BMI = Weight (in kilograms)/ Height (in metres) squared (m2)

Interpretation of BMI values in adults

Underweight BMI <18
Healthy body
BMI 18 to 25
Overweight BMI 25 to 30 or
waist circumference >88 cm (F) or
>102 (M)
Obesity BMI >30 or
waist circumference >88 cm (F) or
>102 (M)

In children, age needs to be considered when defining
overweight and obesity

Underweight BMI <18
Healthy body
BMI 18 to 25
Overweight WFH >2 standard deviations above
WHO Child Growth Standards median
Obesity WFH >2 standard deviations above
WHO Child Growth Standards median


  • High energy (i.e. calorie) intake: eating too much, eating a lot of fatty food
  • Low expenditure of energy: sedentary lifestyle, no exercise or limited activity
  • Disease: hypothyroidism, diabetes mellitus, pituitary cancer

Raised BMI is a major risk factor for:

  • Cardiovascular disease: heart disease and stroke
  • Diabetes mellitus
  • Musculoskeletal disorders: osteoarthritis
  • Some cancers: endometrial, breast, ovarian, prostate, liver, kidney, gallbladder, kidney
  • Obstructive sleep apnoea
  • Fatty liver, gallstones

Clinical features

  • Overweight
  • Difficulty breathing
  • Poor sleeping patterns
  • Joint damage due to weight
  • Low fertility
  • Poor self-image, antisocial, depression
  • In children, also increased risk of fractures, hypertension, cardiovascular disease, insulin resistance


  • Blood pressure
  • Blood glucose
  • Cholesterol


  • Advise patient to reduce carbohydrate and fat intake and increase fruit, fibre and vegetable
  • Refer patient to a nutritionist for individualised diet counselling, and to compile a diet plan
  • Advise patient to control appetite, participate in hobbies, treat any depression
  • Advise patient to increase physical activity and exercise daily. Advise to start slowly and build up
  • Warn the patient of their high risk of diabetes, heart disease, hypertension, stroke, and general
    poor health
  • Encourage patient not to give up even when the weight loss process is slow

Prevention and health education

  • Society and community choices: make healthier food the most accessible, available, and affordable food, and regular physical activity
  • Individuals should:
    • Limit energy intake from total fats and sugars: reduce fatty meat, palm cooking oil (replace with sunflower, olive, corn oil)
    • Increase consumption of fruits and vegetables, as well as legumes, whole grains and nuts
    • Engage in regular physical activity (60 minutes a day for children and 150 minutes spread through the week for adults)
    • Stop other habits that increase risk of non-communicable diseases, e.g., tobacco smoking, alcohol abuse