Washington, Jan. 25 (Reuters): Dieters got a bit of hope yesterday from a study that shows a change in a single gene in mice allows them to eat as much as they want while staying thin — and living longer in the bargain.
Many studies have shown that animals live longer when they eat, on average, about 30 per cent less than normal. The findings have led scientists to speculate that people, too, can extend their lives by dieting.
But no one quite understands why semi-starvation can help an animal live longer. Studies suggest it seems to have something to do with insulin and metabolism. One theory has been that if an animal eats less, the body produces fewer cell-damaging “free radicals” as a byproduct of metabolising food.
Dr C. Ronald Kahn of the Joslin Diabetes Center at Harvard Medical School and colleagues genetically engineered a mouse that lacked a gene called fat-specific insulin receptor. This change limited the action of insulin on fat cells.
The mice, which they nicknamed FIRKO mice (for fat-specific insulin receptor knock-outs), fed freely without gaining much fat and also lived longer than normal mice.
They had 50 to 70 per cent less fat, no matter what they ate, and also were less likely to develop diabetes than normal mice.