It is common to find obese people -- even morbidly obese people -- who are healthier than their condition would normally allow.

Working with subjects with a body mass index of about 56, a team of researchers in Spain and Cambridge investigated the inflammatory and insulin signalling pathways in the patients' visceral adipose tissue and have published their findings in the Disease Knowledge Environment of the Biochemical Journal.

Barbarroja et al. found that the 'healthy' obese lacked an inflammatory response that was found in the unhealthy, insulin-resistant, obese.

The reason, they suggest is that there are pathways common to obesity yet unrelated to insulin resistance and pathways that lead to insulin resistance for a similar degree of obesity. It is the inflammation response that effects insulin resistance, through the expression of the cytokines interleukin 1β and interleukin 16.

Professor Peter Shepherd, Chair of the Editorial Board of the Biochemical Journal, said: "This is a very interesting finding and provides important clues as to why some obese people go on to become diabetic while others do not. It will be interesting to see if similar correlations exist with other diseases associated with obesity, such as cancer and heart disease."