Scientists zero in on obesity pill 'that could replace the treadmill'

A pill for obesity is a step closer, with two separate studies showing that it may be possible to influence the body’s tendency to build up damaging fat deposits beneath the skin.

Scientists at Harvard University have created a way of screening potential drugs that turn white fat cells – which are "bad" – into the brown fat cells that are healthier. They have already identified two compounds that work on human cells growing in the laboratory.

Researchers believe it may be possible to lower the levels of white fat, which is linked with diabetes and heart disease, by increasing the proportion of brown fat, which burns off excess energy. It could lead to a “pill that can replace the treadmill” for the control of obesity, they said.

Meanwhile, Imperial College researchers in London have identified an enzyme that drives the craving for sugar in the brain’s hypothalamus, which regulates food intake. The scientists believe the enzyme, called glucokinase, could be a viable target for an anti-obesity drug.

“This is the first time anyone has discovered a system in the brain that responds to a specific nutrient, rather than energy intake in general. It suggests that when you’re thinking about diet, you have to think about different nutrients, not just count calories,” said James Gardiner of Imperial College, who led the study published in the Journal of Clinical Investigation.

Tests on rats showed that boosting the activity of the enzyme within the brain caused the animals to consume more glucose in preference to normal food. A drug targeting glucokinase or its metabolic pathway could potentially prevent obesity by lowering the desire for sugary foods, the scientists suggest.

“Our brains rely heavily on glucose for energy. It’s clearly a very important nutrient, but in our evolutionary past it would have been hard to come by. So we have a deep-rooted preference for glucose-rich foods and seek them out,” Dr Gardiner said.

The Harvard study, published in Nature Cell Biology, meanwhile suggests that a drug could be developed that targets the conversion of white fat into brown fat, which could be healthier for obese patients as it would reduce the chances of developing type 2 diabetes, said Chad Cowan of Harvard and Massachusetts General Hospital in Boston.

Dr Cowan found that two small molecules are able to trigger the conversion of fat stem cells, which would normally produce white fat, into brown-like fat cells, which burn excess energy and thereby reduce the overall size and numbers of white fat cells.

“You’re constantly replenishing your fat tissue so if you were on a medication to convert the cells, each new fat cell would be more metabolically active and would convert to brown fat over time,” Dr Cowan said.