Nature’s answer to obesity crisis

Brown bears, squirrels, bats and frogs could hold the key to why western populations are facing an epidemic of type 2 diabetes, according to professor of medicine Peter Grant. If his theory is proven, it will “completely change the view of diabetes and its cause.”

By 2025, 300 million people worldwide will suffer from type 2 diabetes, up to 85 per cent of whom will die of related heart disease. The condition, associated with obesity, develops when the body’s fat cells secrete proteins involved in both cardiovascular disease and the development of insulin resistance, preventing the body from using glucose as an energy source.

Professor Grant, director of the University’s new £10m Leeds Institute of Genetics, Health and Therapeutics (LIGHT), believes the body wouldn’t become resistant to insulin action and hoard fat in this way without a reason. “It’s a physiological process so there must be some kind of benefit,” he said. “The question is, under what circumstances?” When the body’s fat cells – or adipocytes – become full, they send messages to the brain to slow down and conserve energy. There is one circumstance where these responses are vital – animal hibernation.

He suggests that animals have a basic metabolic response that stores energy and develops insulin resistance in preparation for deprivation, usually during long winter months. In hibernating animals, this response is accompanied by prolonged periods of torpor, but in humans and other animals seasonal variations in light and food are critical in regulating energy utilisation, even though man probably never formally hibernated.

What has changed for man is that we now have constant supplies of food and light. As a result, whilst hibernating animals become insulin resistant to conserve energy in response to fat storage for the winter, then lose it during hibernation, we just continue to put on weight. “We have fractured our relationship with our environment – we no longer respond to seasons and we don’t have a fluctuating food supply. As a result we get obese and what should be a short term protective response to help us over winter becomes chronic, harmful and leads to diabetes and cardiovascular disease,” he said.

The theory will be tested in the LIGHT and could give important insights into potential treatments. “If we could identify the genes analogous to those in hibernating animals there is the real potential to develop novel targets for the prevention and treatment of both diabetes and cardiovascular disease.”