From EurekAlert!, more experimental metabolic engineering: "the research team bred large numbers of mice, fed them a normal chow diet and followed each mouse until its natural death. Half were genetically engineered to make more of a protein in their muscle tissue called uncoupling protein-1. Their littermates did not make excess uncoupling protein. In muscle tissue, uncoupling protein-1 converts the energy from food into heat and mimics the effects of exercise. ... Uncoupling basically means generating inefficient metabolism ... We were a little bit disappointed because we had hoped uncoupling in muscle would slow aging, but maximum lifespan didn't increase. However, the odds of reaching that maximum lifespan did improve in the uncoupled mice. ... mice with the genetic alteration were more likely to live longer, presumably because they were able to avoid age-related diseases. One result appeared in all of the experiments: Decreasing body fat and inflammation in the animals by accelerating muscle metabolism with uncoupling protein delayed death and diseases, including atherosclerosis, diabetes, hypertension and even cancer."