Updated 11 February 2013

Weight loss

Significant weight loss is defined as the loss of 4.5kg or more than 5 percent of baseline body weight over a period of six to 12 months.



Significant weight loss is defined as the loss of 4.5kg or more than 5 percent of baseline body weight over a period of six to 12 months. Weight loss may be voluntary or involuntary, and may be associated with changes in appetite.


All form of weight loss are basically due to energy requirements or expenditure exceeding energy intake, in other words, a state of negative energy balance. Observed weight loss may be due to the loss of body fluids, fat or muscle. The healthy, desirable form is the loss of body fat, with preservation of other tissues.

Intentional weight loss may be for increased fitness, improved appearance, or for medical reasons, such as avoiding the possible complications of obesity, heart disease, diabetes, arthritis or stroke. Various techniques are used for this, the best being a combination of:

  • Kilojoule restriction,
  • Healthy eating patterns,
  • Increased physical activity, and
  • Weight-loss surgery in extreme cases.

Excess weight loss is not encouraged, as it is associated with medical problems such as decreased immunity to infections, osteoporosis, hormonal imbalances, decreased muscle strength and even sudden death.

Involuntary weight loss is associated with many disorders:

  • Hyperthyroidism;
  • Uncontrolled diabetes mellitus;
  • Malabsorption states;
  • Underlying cancer;
  • Chronic illness of any kind, like infections or Aids;
  • Oral/dental problems like mouth sores, braces, tooth or gum infections;
  • Substance abuse like alcohol, nicotine and opiates;
  • Central stimulants like ingredients in medication; and
  • Psychiatric conditions like depression.


The cause for the weight loss must be determined. A good history and clinical examination may make the diagnosis of an underlying cause, which is then confirmed by tests such as blood tests, or imaging (X-rays scans).


Those with voluntary weight loss do not seek treatment as a rule.
Treatment of involuntary weight loss will depend on the underlying cause identified.

(Dr AG Hall)


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