Chronic stress triggers the body's fat cells, instructing them to grow and multiply, according to new research from Australia.
The research helps to explain the already recognised link between stress and obesity and the findings could result in new therapies that shrink fat cells or make them die.
Such fat is said to take on an apple shape in those experiencing a weight gain caused by stress.
Professor Herbert Herzog, director of neuroscience at the Garvan Institute in Sydney, identified a molecule which is released when the body is under stress. It was found to unlock receptors in the body's fat cells causing them to grow.
He said: "If we can interfere before it causes fat to amass, it could have a major impact on cardiovascular disease, diabetes and cancer which all have links with obesity."
Zofia Zukowska, another scientist working on the link, said: "We are hopeful that these findings might eventually lead to control of metabolic syndrome, which is a huge health issue for many."