"The obesity pandemic is the biggest disease that has hit mankind ever in terms [of] numbers. It is killing more people than anything else has ever killed – probably the second world war is not to be counted, but in terms of disease [there are] more deaths from obesity than anything we have known about," he says.
Bloom was knighted in the 2012 new year's honours for his work on understanding and combating obesity and he and his team are currently working to bring two methods of appetite control to the market within the next decade – one an "intelligent microchip", which can send signals to the brain to stop the urge to eat, and the other a treatment that combines two hormones to reduce appetite.
Obesity tends to kill indirectly, he says. Increases in blood pressure increase the likelihood of having a stroke. Higher cholesterol means a person is more likely to have a heart attack. The incidence of Alzheimer's disease is a third higher in obese people. It is now believed that obesity is more important than cigarette smoking in causing cancer, he says.
"As a physician, I see death. I see people suffering, people in wheelchairs from strokes, people dying of cancer, from cancer of the uterus – something five-fold higher in the obese. So you can take most of the cancer of the uterus and say that didn't need to happen. If we had a treatment for obesity, they wouldn't have had that," says Bloom, who is head of the diabetes, endocrinology and metabolism division of Imperial College London in Hammersmith Hospital.
His focus on obesity came as a result of his attention on diabetes. "I was in charge of the diabetic service and most diabetes is caused by people being slightly overweight, so if you could get rid of obesity, diabetes rates would fall to about a third or maybe a quarter," he says. Figures from the US Centers for Disease Control and Prevention, which track obesity rates across American states, show that as the population becomes more obese, the incidence of diabetes increases.
Most of Bloom's career with his team has been focused on gut hormones. The discovery that the oxyntomodulin hormone reduces appetite and could offer a potential new treatment for obesity led to the creation of a spin-off company Thiakis, which was sold to the US pharmaceutical company Wyeth in 2008.
At the Society for Endocrinology's annual conference last year, details were given of the second spin-off from Bloom's work, a treatment that combines two naturally occurring hormones to reduce appetite. Initial tests showed that people consumed 13% fewer calories when they ate a meal after taking the hormones.
A company called Zihipp, half owned by Imperial College, has been formed to manage the new treatment. Funding has been received for drug development for two and a half years by the Medical Research Council, said Bloom, although it will be nine years before the drug gets to market should it pass through the stages and approvals needed. After investment costs have been paid back, initial estimates are that the drug would cost about £1,000 a year for treatment.
A parallel project – described as an intelligent microchip – is also expected to take nine years to get to market. The tiny chip would be attached to the vagus nerve, which plays a role in appetite, and is designed to recognise and process signatures of appetite and then mimic instructions to the brain, reducing the urge to eat.
Prof Chris Toumazou, another Imperial College academic, is working with Bloom in the project. Toumazou specialises in combining electronics and biology in healthcare.
The development of the microchip is one milestone in the advance in the relationship between electronics and biology. Others include the cochlear implant for the deaf.
While the development of the microchip is not as far forward as that of the hormone treatment, Bloom is convinced that they will "crack it" given enough time.
"I happen to be the head of diabetology, therefore I was seeing the consequences of all of this obesity and at the same time I was doing research which turned out – and we didn't know it was going to do this – to control appetite. So this was a piece of real good luck, that my disease interest needed appetite controlling and my research interest turned out to be a new mechanism for controlling appetite," he says.
The time needed to develop the drug could be cut by more than half if conservative checks and balances were loosened, he says.
"I think we might need to treat obesity in a hurry and we are being held up. The Aids lobby forced Aids drugs on to the market before they had finished testing, but they turned out to be bloody useful and lives were saved."
To any critics who would see this as a predictable response, Bloom says: "I just happen to see these people dying and it happens to influence me. I am terribly sorry about that, I will try not to look."
In theory, both the treatments could work together or individually to combat obesity.
At 71, he says that it is "perhaps late in life that I have found something really exciting", but he has no intention of retiring and intends to be chief executive of Zihipp.
