Tomatoes are a fruit and contain sugar. However, if you eat them in low amounts then it should not do any harm. If you eat them in large amounts (such as soups, tomato sauce, etc) then this is where things could start to become problematic.
Tomatoes are also acidic and thats the main reason I don’t eat them.
We have a strict forum foods list if you want a copy of it; just send an email to able900.