Fat is the demon on our diet, supposedly packing in the calories and predisposing us to heart attacks. But at least the original devil would spread the smell of sulphur to announce his presence, our modern tormentor is dark to the senses. Fat, says experts, has no taste. All we can detect is something rather clumsily called "mouth fee". This bit of dogma has recently been put to test by US researcher Timothy Gilbertson, and it turns out to be wrong. His findings may lead to a whole new approach to fat and dieting.