It’s much too soon to get excited -- it’s still in the mouse stage of research -- but a substance being tested by Scripps Research Institute in Jupiter and other centers seems to make obese rodents lose weight and use 5 percent more energy. All without exercise. As the New York Times describes, there are too many unanswered questions at this point to know whether such a substance might do more harm than good. For example, a related study on resveratrol, a substance found in red grapes and wine, offered positive effects at the cellular level only at doses that could be toxic to the animal. The scientists’ aim is to help those who cannot exercise because of disability or illness -- not so much those who don’t want to.