Overfatness has typically been inferred from measures of body mass, such as weight or body mass index. Mass is not always a good measure of fatness, because of the influence of muscle and other lean body tissue. However, measures of body mass index (BMI) still show a correlation with disease risk, and particularly mortality levels, or the risks of premature death. Mortality levels have a ‘tick-shaped’ association with BMI with the highest risks of mortality at increasing levels of obesity over a BMI of 25. There is also a slightly increased risk of mortality at BMI levels below 20, which is largely explained by the presence of existing disease and smoking, both of which are causes of lower weight and higher mortality.

Fat is the highest source of food energy that can be obtained (9kcal/g compared with 4.5kcal/g for carbohydrate or protein), so fatty foods would have had survival value in a hunter-gatherer

environment. Relative risk (RR) is an indication of the proportional increase in risk of disease from a standard measure of 1.0. Hence, a RR of 2.0 means the risk of contracting that disease is twice that of someone with a normal BMI.


  • Digg
  • Sphinn
  • Facebook
  • Reddit
  • StumbleUpon
  • Yahoo! Bookmarks
  • LinkedIn
  • Twitter