Putting on weight in middle age increases the risk of an early death.
New research shows that people who put on the pounds in their 40s and 50s are up to 30 per cent more likely to die at a younger age.
The Swedish experts say that the "slightly unhealthy traits" of elevated blood pressure and cholesterol put people at increased risk of suffering from a heart attack or stroke.
Alarmingly, most people show no symptoms and "feel generally well" - leaving them unaware of the ticking health timebomb.
Dr. Lena Lonnberg, of Vastmanland County Hospital in Sweden, said: "Many people in their 40s and 50s have a bit of fat around the middle and marginally elevated blood pressure, cholesterol or glucose but feel generally well, are unaware of the risks and do not seek medical advice.
"As a general rule of thumb, even if you feel well, check your blood pressure every year, avoid smoking, keep an eye on your waist circumference and last, but definitely not least, be physically active every day."