Quit smoking if you are looking to reduce the ‘hidden’ abdominal fat, known as visceral fat, suggests a study.

While smokers tend to have lower body weights than non-smokers, they tend to have visceral fat, which can be explained as the unhealthy fat deep inside the abdomen, and around organs such as the liver, heart, and kidneys. Even a thin person with a flat stomach can have unhealthy amounts of visceral fat.

The new study published, in the scientific journal Addiction, offers evidence that smoking may cause visceral fat to increase in the body and raise the risk of serious illnesses like heart disease, diabetes, stroke, and dementia.

“This study found that starting to smoke and smoking over a lifetime might cause an increase in belly fat, as seen by measurements of waist-to-hip ratio. In a further analysis, we also found that the type of fat that increases is more likely the visceral fat, rather than the fat just under the skin,” said lead author Dr German D. Carrasquilla from the University of Copenhagen in Denmark.

For the study, the team looked at 1.2 million people who started smoking and over 450,000 lifetime smokers. They also conducted a study on body fat distribution with over 600,000 people.

They examined how DNA variants linked to smoking habits and belly fat are associated with fat compartments in different parts of the body. Their results show that “excess abdominal fat in smokers was predominantly visceral fat”.

“From a public health point of view, these findings reinforce the importance of large-scale efforts to prevent and reduce smoking in the general population, as this may also help to reduce abdominal visceral fat and all the chronic diseases that are related to it. Reducing one major health risk in the population will, indirectly, reduce another major health risk,” Dr. German said.