The term 'fat but fit' is a fallacy that risks accelerating the spread of global obesity, according to new research which throws cold water on a commonly held medical belief.
Medical scientists from the University of Birmingham have countered the theory that people can be fat but medically fit with new research which claims that obese people remain at greater risk of developing heart disease, strokes and heart failure than people of normal weight.
The study, as yet unpublished, was presented at the European Congress on Obesity in Portugal, this week. It looks at the medical records of 3.5 million people in the U.K. between 1995 and 2015 to assess the legitimacy of the 'fat but fit' theory.
Medical research has previously suggested that obesity can have little impact on a person's chances of contracting various harmful diseases if they are otherwise medically healthy. However, the latest research, which tracked obese but "metabolically healthy" people, found that they continued to be at higher risk of developing diabetes and heart-related diseases later in life.
Dr Rishi Caleyachetty, who led the research, said the new research indicates that health professionals need to change their approach to obesity cases.
"This is the largest prospective study of the association between metabolically health obesity and cardiovascular disease events.
"The priority of health professionals should be to promote and facilitate weight loss among obese persons, regardless of the presence or absence of metabolic abnormalities."
The study focused on four cardiovascular diseases in particular: coronary heart disease (CHD); cerebrovascular disease (transient ischaemic attack or stroke); heart failure; and peripheral vascular disease (PVD).
It found that obese people were 50 percent more likely to suffer from CHD, and between 7 percent and 11 percent more likely to develop cerebrovascular disease and PVD. It also found the risk of heart failure doubled among obese patients.
"Metabolically healthy obese individuals are at higher risk of coronary heart disease, cerebrovascular disease and heart failure than normal weight metabolically healthy individuals," Caleyachetty added.
The British Heart Foundation, the U.K.'s biggest funder of cardiovascular research, said that the research would help to dispel an "age-old myth."
"This is another study highlighting that, if you are overweight, you are more likely to suffer from heart disease," said Dr Mike Knapton, associate medical director at the British Heart Foundation.
"It's not often that research on this scale and magnitude is able to clarify an age-old myth. These findings should be taken extremely seriously and I'd urge healthcare professionals to take heed."
It is estimated that 28.1 percent of adults in the U.K. are recognised as clinically obese – having a Body Mass Index greater than 30. In the U.S., this figure rises to approximately one third.