An enzyme named eIF2alpha kinase (GCN2) was shown to profoundly regulate fat metabolism in mice.
Scientists provoked the mice into starvation mode by removing a single amino acid named leucine from their diets. By doing this, the body represses fat synthesis and consumes virtually all of its stored fat. After 17 days of a leucine-deficient diet, the mice with GCN2 lost 48% of their liver mass and 97% of the fat from their abdomens. In contrast, the mice without GCN2 kept a steady liver mass and lost only 69% of abdominal body fat.
The mice without GCN2 did not lose as much fat as the mice with GCN2. Furthermore, they developed symptoms that could lead to fatty liver disease. In most events of rapid weight loss, the liver tends to take a beating. However, the fastidious weight loss in the mice with GCN2 occurred because of the repressed synthesis of new fats coupled with the depletion of stored fats. This says a lot for safe handling when it comes to teamwork.
