Could a virus contribute to weight gain?

A Vasilakopoulou 1,2 and C W le Roux1

1Department of Metabolic Medicine, Hammersmith Hospital, Imperial College, London, UK

2Laiko General Hospital, Athens, Greece
Correspondence: Dr CW le Roux, Metabolic Medicine, Hammersmith Hospital, Imperial College London, London W12 0NN, UK. E-mail:

Received 2 November 2006; Revised 25 January 2007; Accepted 25 January 2007; Published online 10 April 2007.


Objective: Obesity is a serious public health problem associated with increased morbidity and mortality. Although the causes for obesity are unclear, it seems that environmental, genetic, neural and endocrine factors contribute to its development. However, the rapid global spread of obesity resembles epidemiologically the spread of an infectious disease. Thus far, little consideration has been given to the possibility that the epidemic of obesity could be due to an infectious agent. Seven viruses and a scrapie agent have been implicated in obesity.

Design: This review evaluates the infectious pathogens and the evidence that these viruses are associated with obesity and concludes that a strong evidence base is emerging that associates certain viruses with obesity.

Conclusion: More work is however required to elucidate the mechanisms of weight gain after viral infection. In the mean time, discounting viruses as a contributing factor to obesity would deprive us of a potential new avenue of investigating and treating the ever increasing epidemic of obesity.