Researchers have warned that obese people that are otherwise healthy are still more likely to have their lives cut short by fatal diseases.
So basically being 'fat but fit' is impossible.
Published in the Journal of the American College of Cardiology the new study by the University of Birmingham, looked at four different groups of three-and-a-half million people.
It was the biggest study of its kind and examined whether or not an overweight or obese person without diabetes, hypertension or high cholesterol (considered metabolically healthy) was still as fit as a person at a healthier weight.
Participants were categorised based on their BMIs and data was collected from the patients for 5.4 years all up.
Scientists found that those people that were obese were more likely to develop heart failure, coronary heart disease and cerebrovascular disease, which causes strokes.
Breaking down the results specifically, the data revealed they were 96 per cent more likely to develop heart failure.
They were 50 per cent more likely to develop coronary artery disease and seven per cent more likely to get cerebrovascular disease.
Previous research has declared that up to one in three obese people are 'healthy' despite carrying too much weight, which led to widespread use of the term 'fat but fit'.