The research was led by Swedish scientists who used a new technique to examine obesity and being overweight as a trigger of cardiovascular disease.
Previously, significant links have been found, but it has never been evident whether obesity was the cause or just a sign of a separate underlying cause, as clinical trials that include long-term follow-ups are harder to implement.
One study reported that young girls who are overweight are more likely to be obese and have a greater risk for heart disease when they grow up. Another suggested that belly size is a more accurate predictor of heart disease than obesity.
The goal of the current study was to determine whether obesity is an actual cause of cardiovascular disease or is just a marker of something else in the person's lifestyle that causes the disease.
Tove Fall, a researcher at the Department of Medical Sciences and the Science for Life Laboratory, Uppsala University, who coordinated the study together with researchers from the Karolinska Institutet and Oxford University explained:
"We knew already that obesity and cardiovascular disease often occur together. However, it has been hard to determine whether increased BMI as such is dangerous. In this study we found that individuals with gene variants that lead to increased body-mass index (BMI) also had an increased risk of heart failure and diabetes. The risk of developing diabetes was greater than was previously thought."
The scientists studied close to 200,000 participants from Europe and Australia to see whether a gene variant in the FTO gene - one that controls appetite and can raise a person's BMI - is also associated with several cardiovascular diseases and metabolism.
The risk variant is often seen in the population and each copy of the risk variant raises BMI by an average of 0.3-0.4 units. A person's genome is not influenced by social and lifestyle factors because it is established at conception when the embryo gets half of each parent's genome - a process known as Mendelian randomization.
Erik Ingelsson, professor at the Department of Medical Sciences and the Science for Life Laboratory, Uppsala University, said:
"Epidemiological studies look for associations in large populations, but it is usually difficult to reliably determine cause and effect - what we call causality. By using this new genetic method, Mendelian randomization, in our research, we can now confirm what many people have long believed, that increased BMI contributes to the development of heart failure.
We also found that overweight causes increases in liver enzymes . This knowledge is important, as it strengthens the evidence that forceful societal measures need to be taken to counteract the epidemic of obesity and its consequences."
The outcomes revealed that an increase of only one unit of BMI raises the risk of developing heart failure by an average of 20%.
Additionally, the study confirmed that obesity leads to:
- higher blood pressure
- higher insulin values
- worse cholesterol values
- increased inflammation markers
- raised risk of diabetes
Written by Kelly Fitzgerald