We want only to annihilate it, or at least keep it to a barely visible minimum. In fact, there was a time back in the s when doctors thought it was a good thing — though they cautioned against obesity, they suggested gaining a few pounds to treat nervousness and contagious disease. These were good times for fat. It was appreciated for its positive qualities — to supply energy and symbolise well-being. But new research is showing us that fat is just as crucial to our survival and health as our colon, lungs and heart.