Regularly grabbing headlines in the national press, everyone knows obesity is a growing problem in the UK. Dubiously termed 'a crisis on the same scale as global warming' by Health Secretary Alan Milburn, this is nevertheless one of the biggest causes of ill health in the developed world, being implicated in a range of conditions from heart disease to cancer. A quarter of the UK population is estimated to be obese, and this will double in the next 25 years unless current trends are halted. Government measures have largely focused on the individual, encouraging people to lead healthier lifestyles by exercising and being more aware of what they are eating, following the simple argument that if you take in less energy than you expend, you will lose weight. While this is true, the approach has proved largely ineffective. So why do people eat more than they need? Recent research suggests that genetics play an important role in creating this energy imbalance.

Herpes viruses have the unique ability to persist in the human body for a lifetime, unhindered by the immune system or modern medicine. This means once you get infected, there is no way to get rid of the infection. Most of us will recognise the Epstein-Barr virus, which causes glandular fever, as a familiar example of herpes viruses (as many as 80% of us are already infectet, but luckily it's harmless in most of us). Kaposi's sarcoma associated herpes virus on the other hand, is believed to cause nasty cancers such as Burkitt's lymphoma. This ability to persist in the body is a result of the virus being able to avoid detection by the immune system.