Between 2003 and 2017 the percentage of deaths attributable to smoking are calculated to have decreased from 23% to 19% while deaths attributable to obesity and excess body fat are calculated to have increased from 17.9% to 23.1%. The authors estimate that deaths attributable to obesity and excess body fat overtook those attributable to smoking in 2014.
To examine changes in the prevalence of smoking, obesity and excess body fat in adults, the authors analysed data collected between 2003 and 2017 as part of the Health Surveys for England, and Scottish Health Surveys, on 192 239 adults across England and Scotland, who were 50 years old on average. Participants reported whether they had ever regularly smoked and their height and weight were measured by trained interviewers or nurses. The researchers combined their data with estimates of the risk of dying from smoking (17 studies) or obesity and excess body fat (198 studies), to calculate the number of deaths that could be attributed to smoking and obesity and excess body fat.
The authors found that while obesity and excess body fat likely accounted for more deaths than smoking since 2006 among older adults, smoking is still likely to contribute to more deaths than obesity and excess body fat among younger adults. The authors suggest that among those aged 65 and over and 45-64, respectively, obesity and excess body fat contributed to 3.5% and 3.4% more estimated deaths than smoking in 2017, while smoking accounted for 2.4% more estimated deaths than obesity and excess body fat among those aged 16-44.
The analysis also suggests that gender influenced the contributions of smoking, obesity and excess body fat to estimated deaths. Obesity and excess body fat may have accounted for 5% more deaths in 2017 than smoking in men, compared to 2% more deaths in women. Estimated deaths due to obesity and excess body fat are thought to have increased by 25.9% for women and 31% for men between 2003 and 2017, while deaths to due smoking are thought to have decreased by 18% for women and 14% for men.
While body mass index (BMI) as a body composition assessment tool has long had its critics, recent research has highlighted a new potential drawback in that it could prevent people of certain ethnicities from having their risk for type 2 diabetes assessed earlier. A psychologist and weight management specialist at the American hospital, Cleveland Clinic, stresses the importance of physicians and patients being aware of different cut-off points based on their ethnicity.
Dr Leslie Heinberg explains that recently, researchers in the UK discovered that the cut-off BMI number associated with a higher risk of type 2 diabetes varies between different patient populations. For example, a BMI of 30 or above was linked to a higher risk for white people. For Black people, the cut-off number was 28 or above. For South Asian people it was 23.9 or above and for the Middle Eastern population, the BMI cut-off was 26 or above.
The problem is that some healthcare providers might only be making recommendations for diabetes-related lifestyle changes or treatment options based on the risk level for white people. This means that other populations might not get the medical interventions they need in time.
Here, Dr Heinberg, explains why BMI is still used and gives some tips for how people of colour can make sure they’re on the right track despite the discrepancies.
Where did BMI come from?
The formula for calculating body mass was the creation of a Belgian mathematician, astronomer, sociologist and statistician named Lambert Adolphe Jacques Quetelet. Quetelet wasn’t focused on studying obesity when he developed what was first known as the “Quetelet Index” (your weight in kilograms divided by the square of your height in metres, or Kg/M²). He was looking at years of crime data that he compiled to link crime to social conditions. In doing so, he noticed a relationship between an adult’s height and weight.
In 1972, American physiologist Ancel Keys gave the Quetelet Index a new name as he thought the formula was a good way to identify obesity. He referred to it as the body mass index.
“It’s a ratio that takes height into account because taller people weigh more than shorter people,” says Dr Heinberg. “It was developed more for actuarial tables and to determine which people are at a higher risk for mortality. It’s something that makes sense when you look at a very large population.”
Dr Heinberg adds that today, many organisations and businesses still rely on BMI when it comes to providing things like insurance or medical procedures.
The drawbacks of BMI
Dr Heinberg says that BMI can be a pretty blunt instrument for health because it leaves a lot of physical attributes out of the equation.
“It doesn’t take into account a lot of things about an individual. You can ask somebody for their height and weight and it becomes a very easy assessment in comparison to a full and comprehensive evaluation. When we think about an individual’s health and their health risks, taking their background information into account is helpful. But when you’re looking at a million people, you just can’t do that.”
Other physical signs of health risks
While BMI is one way of measuring risks, Dr Heinberg says there are other physical clues to watch out for.
“We do know things like waist circumference, waist-to-hip ratio and where you hold excess weight might play an even more important role when it comes to metabolic diseases,” she says.
For instance, if you have an apple body shape or a pear shape, the excess abdominal weight of an apple shape is associated with more cardiovascular risks and metabolic disease. “Also, with things like obstructive sleep apnoea, neck circumference seems to be important. It all goes way beyond just BMI.”
Ho et al. Changes over 15 years in the contribution of adiposity and smoking to deaths in England and Scotland. BMC Public Health 2021. DOI: 10.1186/s12889-021-10167-3
Cleveland Clinic: Patients and Physicians Should Take Note of Ethnicity-Specific Body Mass Index (BMI) Guidelines