Obesity is thought to cause 1000 premature deaths a week in the UK. By focusing on the way the body controls appetite, Professor Steve Bloom and colleagues at Imperial College London are investigating anti-obesity therapies based on naturally occurring hormones and neurotransmitters.

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All current methods of weight control have significant problems. Surgery can be effective for severe obesity, but carries a 3 per cent mortality rate. Anti-obesity used drugs have unpleasant side-effects. More generally, dieting suffers a high failure rate.

A major challenge is understanding the body's own physiology. The body has homeostatic set points to maintain body weight, but it is more sensitive to weight loss than weight gain. So when we lose weight, we have a powerful drive to eat more to put weight back on.

Control of appetite is therefore likely to be key to weight-control strategies. The Imperial group is investigating the hormonal and neural systems underpinning appetite control – and developing new interventions based upon them.

Control of energy balance, eating, metabolism and physical exercise is complex. Nevertheless, Professor Bloom's group has identified several key players in this system, and shown that gut hormones can influence appetite. Indeed, injections of oxyntomodulin, a hormone released by the small intestine after eating, not only reduced energy intake but also increased subjects' spontaneous activity.

The team is now working on a formulation of the hormone that can be injected once a day or less, as well as investigating the therapeutic potential of other factors, including neuromedin, neuropeptide S and PYY3-36.

Image credit: Anthea Sieveking

External links

• Wynne K et al. Oxyntomodulin increases energy expenditure in addition to decreasing energy intake in overweight and obese humans: a randomised controlled trial. Int J Obes (Lond) 2006 [Epub ahead of print].
• Wynne K et al. Subcutaneous oxyntomodulin reduces body weight in overweight and obese subjects: a double-blind, randomized, controlled trial. Diabetes 2005;54(8):2390–5.