It all depends on the foods you are eating. The reason you feel like vomiting is because you are forcing yourself to eat a lot of foods that are low in fat. Therefore you have to eat more in order to get the fat grams in. Try to vary your foods so that some are higher in fat. Don't misunderstand and take that as eating very fatty foods because you will then experience TEs. For example, try to add light oils to salads, or choose low fat instead of fat free. Add a few nuts to your diet.
I know it can be hard to start a new "diet", but you soon will get to know which foods your body can handle and which you can't have. I hope this helps. -Mel