Fruits and vegetables are classified from both a botanical and culinary standpoint. Botanically speaking, tomatoes fit the definition of a fruit. their sweet taste, fruits tend to have a higher amount of natural sugar and calories. A healthy diet begins with fresh vegetables and fruits which play a major role low carb diet, you should beware of high sugar fruits and vegetable. Tomato Turnip greens. Watercress Zucchini. Vegetables That Are High. The classical vegetable/fruit story is the tetchy tale of the tomato. percent sugar by weight, and tropical fruits, by and large, are even sweeter.