Despite the fact that tomatoes are a fruit. Fruits are usually high in carbohydrates but tomatoes are uncharacteristically low in carbs which makes them great for a low carb diet. Tomatoes have only 2-3 net carbs per 3.5 ounces. Which is like ten times lower than the carbohydrate content of other fruits. When I experimented with an alkaline keto diet, I ate lots of tomatoes every day and still managed to stay under 50 grams of carbs per day. Tomatoes are a healthy alkaline vegetable that you can enjoy while you're on a low carb diet.