11. Relationship between BMI and Death Rates from Different Diseases


The official approach to obesity is based on the fact that there is an increased incidence of diabetes, heart attacks and certain cancers as the BMI increases. But there are many other causes of death and to obtain a comprehensive perspective we need to consider all the different diseases/conditions which contribute to ill-health and death.

Katherine Flegal’s team, whose detailed work (BLOG 10) provided convincing evidence that those in the BMI “overweight” category had a lower death rate than those with a “normal” BMI has analysed  the causes of death in the different BMI categories(1). The results are shown in Table 1.


Cause of death<18.518.5-2525-30>30
Coronary heart disease+30-12+6
Other   cardiovascular+80-5+36
Lung   cancer00-10-7
Obesity   related cancer00-3+20
All   other cancers+30+3+2
Diabetes/kidney   disease00+15+34
Chronic   respiratory+160-30-6
Acute   respiratory/infectious+80-8-3
Other   causes+60-52+13


The findings for the “overweight” category confirm that there is an increase in the deaths from diabetes but that the reductions in deaths from a variety of other causes are actually less than those in the “normal” range so that the risks of dying are substantially lower in the “overweight range” than in the “normal” range. It is clear from these results that while the concern about the dangers of diabetes in the overweight category is justified, it does pales into insignificance when all the other information is taken into consideration. For chronic respiratory conditions and injury the risks of dying are less in people overweight than in those who have a BMI which is normal. In the light of this information why should anyone who is overweight be advised that it would be beneficial to lose weight???

In another study with 12,725 Americans who were not disabled at the outset the life expectancy was assessed. The results are shown in Table2. For men with BMI in the ranges 25-30 and 30-35 the life expectancy for those aged 65+ is greater than for those with a “normal” BMI. For women it is clear that the highest life expectancy is in the BMI range 30-35 which is Class 1 obesity. These results are particularly relevant because it has been done with the age range when the majority of deaths occur.

It should also be noted that as in the other studies there is a relatively high death rate in those who are underweight(2).

Further confirmation is available from the results of a study in Norway  based on 1.7 million people where once again the highest life expectancy was exhibited by those who were in the BMI category overweight. It was also noted that those with a normal BMI had a lower life expectancy than many in the obese category(3).



Men age years     
 75 6.68.510.2 9.6 8.5
 85 3.95.0 6.1 8.5 5.3
Women years     
856.98.8 9.311.3 8.6


A study in Finland involving 11,997 women who were in the 7/8 month of pregnancy initially and were monitored from 1966 to 1994 found that those in the “overweight” BMI category had a consistently lower mortality than those of “normal” weight. During the period 633 of them died. The results are shown in Table 3(4).



SMR(per 100,000 years)183181149258


The relationship between body weight and mortality was studied in 7,985 middle-aged men based in centres in Europe which included Finland, the former Yugoslavia, Italy, Greece and the Netherlands was started in 1960(5). It continued for 25 years during which time 3,777 died. It was found that:

A BMI of 25-30 was not related to mortality”

To summarise, there is a huge amount of research demonstrating that the lowest risk of all-cause mortality is in those who are overweight as determined by BMI. Furthermore in older people there are strong indications that even higher weights may be beneficial to health. There is absolutely no doubt that the official UK public health policies and strategies dramatically overplay the dangers of being overweight. While there is no argument that those who are extremely obese have serious health problems the authorities have exaggerated the dangers by assuming, quite wrongly, that similar health hazards apply to those who are overweight or mildly obese. As in will show in subsequent posts if these people attempt lose weight they are much more likely to damage their health than if they remain at their existing weight.


  1. K M Flegal et al (2007) Journal of the American medical Association 298 (17) pp 2028-2037.
  2. S A Such et al (2007). Archives of Internal Medicine 167 (8) pp774-788.
  3. H T Waaler (1984) Acta Medica Scandinavica supplement 679 pp 1-56.
  4. E Laara and Paula Rantakallio (1996) Journal of Epidemiology and Community Health 50 pp408-414.
  5. T L S Visscher (2000) American Journal of Epidemiology 151 pp660-666.




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