请问这个句子如何取非啊？

Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.
这是一个OG中的句子，请问如何取非啊？

另外，能够详细讲讲如何对带有few,only, no, none等这种否定意义词的句子取非吗？感谢！