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Contrary to popular prognosis, Just because a person is fat does not mean their not fit.

 According to a controversial study published online in the European Heart Journal, obesity does not necessarily determine a persons metabolic health and fitness.

Dr Francisco Ortega (PhD), a research associate affiliated to the Department of Physical Activity and Sport, University of Granada (Spain), and at the Department of Biosciences and Nutrition, Karolinska Institute in Stockholm, Sweden conducted a study under the direction of Professor Steven Blair, who is responsible for the long-running "Aerobics Center Longitudinal Study" (ACLS).

According to the study,43,265 clinically obese participants were recruited to the ACLS and studied between 1979 and 2003. They completed a detailed questionnaire, including information on their medical and lifestyle history, and they had a physical examination that included a treadmill test to assess cardio-respiratory fitness and measurements of height, weight, waist circumference, and their percentage of body fat. Blood pressure, cholesterol and fasting glucose levels were also measured. The study participants were followed until they died or until the end of 2003.

Results suggested that there are a subset of obese people who are metabolically healthy -- they don't suffer from conditions such as insulin resistance, diabetes and high cholesterol or blood pressure -- and who have a higher level of fitness, as measured by how well the heart and lungs perform, than other obese people.

Obesity in itself did not have a detrimental effect on their health, and researchers say doctors should bear this in mind when considering what, if any, interventions are required, say the researchers.

"It is well known that obesity is linked to a large number of chronic diseases such as cardiovascular problems and cancer. However, there appears to be a sub-set of obese people who seem to be protected from obesity-related metabolic complications," said Dr Ortega, first author of the study.

Many medical practitioners omit the fact that common obesity related health complications are in fact genetically determined. Persons diagnosed with diabetes, cardio-vascular diseases or even cancer are genetically predisposed to such issues (i.e. it runs in the family) and medical history should be the primary determinant of whether or not a person's weight is a causal or sustaining factor in these issues.

 The findings showed 46% of the obese participants were metabolically healthy with a 38% lower risk of death from any cause than their metabolically unhealthy obese peers. The risk of developing or dying from cardiovascular disease or cancer was reduced by between 30-50% for the metabolically healthy but obese people, and there were no significant differences observed between them and the metabolically healthy, normal weight participants.

"There are two major findings derived from our study. Firstly, a better cardio-respiratory fitness level should be considered from now on as a characteristic of this subset of metabolically healthy obese people. Secondly, once fitness is accounted for, our study shows for the first time that metabolically healthy but obese individuals have similar prognosis as metabolically healthy normal-weight individuals, and a better prognosis than their obese peers with an abnormal metabolic profile," The authors write.

The only common ailment among obese women, regardless of their level of physical fitness is a delayed period. However, even normal weight women can have the same issue and both groups can be regulated with birth control.

It is well known that maintaining a healthy weight is one of the ways to avoid developing heart problems. However, as a result of another study which found that overweight and obese people had a much lower mortality rate than underweight or morbidly obese persons, the authors claim:

 "We believe that no evidence exists that proves weight reduction in itself has a positive prognostic value after ACSs. Actually some evidence suggests that weight loss after ACSs might in fact have a negative effect. We believe that given the current state of our knowledge, obesity paradox requires much more attention and deserves to be recognized in the guidelines...The available studies, together with previously published study data, permit the conclusion that  fat tissue has several beneficial effects, for example in its action as an endocrine organ or as an aid in protecting against hip fracture. Obesity may carry benefit up to a certain degree, and it should be recognized that obesity is not necessarily associated with abnormal metabolic function."