Research links excess weight to premature death


Increasingly many people worldwide are either overweight or obese. Being overweight or obese is associated with a higher risk of dying prematurely than being normal weight, according to a collaborative study conducted at Harvard H T Chan School of Public Health and Cambridge University. The study was published on July 13, 2016.


How does one know whether one is overweight or obese? This is done by calculating one’s Body Mass Index (BMI).

BMI is one’s weight in kilogrames divided by one’s height in metres squared. Because the calculation requires height and weight, it is inexpensive and easy to use for both clinicians and for the general public.

Since in adults above 19 years, height does not change, one can monitor their BMI by keeping an eye on the changes in weight.

Once you have done the above BMI calculation, the table on the top right is an indicator of one’s weight status:

The harmful effects of excess body weight on chronic disease have been well documented. These include increased risk for diabetes, cardiovascular (heart) diseases and cancer. 

To obtain an unbiased relationship between BMI and mortality, it was essential to analyse individuals who had never smoked or had no existing chronic disease. Smokers tend to weigh less than non-smokers, but have a much higher mortality rate

In order to obtain more definitive evidence of the association between excess body weight and premature mortality, researchers joined forces in 2013 in order to establish Global BMI mortality collaboration involving 500 investigators from 300 global institutions.

The researchers looked at data from more than 10.6 million participants from 239 studies carried out between 1970 and 2015, in over 32 countries, in four continents. Out of 10.6 million people, 4 million adult participants were followed over 14 years and 1.6 million deaths were recorded across these studies.

The results showed that participants with the normal/healthy weight had the lowest risk of premature mortality.

The risk of mortality increased significantly over the overweight range.

The BMI of 25-27.4 was associated with seven percent higher risk mortality, the BMI of 27.5-29.9 was associated with a 20 percent higher risk, the BMI 30-34.9 was associated with a 45 percent higher risk, the BMI of 35-39.9 was associated to 94 percent higher risk and the BMI of 40-60 had a three-fold risk. 

Every five units higher BMI above 25kg/sq. m was associated with a 31 percent higher risk of premature mortality. Participants who were underweight also had a higher mortality risk

Looking at specific causes of death, the study found that for each five unit increase in BMI above 25 kg/sq. m, the corresponding increase in risk were 49 percent for cardiovascular mortality, 38 percent for respiratory disease mortality, and 19 percent for cancer mortality.

Researchers also found that the hazards of excess body weight were greater in younger than older people, and in men than in women

BMI is one of the parameters that are assessed at Allan Galpin Health Centre whether one is sick or not. Health education is then given to the client on lifestyle interventions necessary to attain/keep within a safe BMI range.

The author is Director of Medical Services at Uganda Christian University (UCU)