How to Enjoy Your Favorite Tomato Soup on a Low-Carb Diet

With vibrant tomatoes, rich cream and Italian seasoning, tomato soup is the perfect comfort food —and those croutons on top or grilled cheese triangles on the side can be pretty satisfying, too. Plus, tomatoes are a good source of the antioxidant lycopene, according to the Mayo Clinic, especially when they've been cooked.

But if you're following a restrictive low-carbohydrate diet — or you only like your tomato soup paired with starchy sides — you may need to make some adjustments in order to enjoy this favorite food while still reaching your goals. Here's what you should know about tomato soup and counting carbs.

Tomato soup is mostly carbohydrates: According to the USDA, it's about 86% carbs compared to just 6% fat and 8% protein. While ingredients and ratios vary by recipe, a half-cup serving of Campbell's condensed tomato soup (measured before adding water) has about 19 grams of total carbohydrates. The brand's reduced-sodium version (which is also fat-free) is even higher in carbs, with 20 grams total, according to the USDA.

Also problematic is that almost all commercial tomato soups contain added sugar or high-fructose corn syrup, which can add 10 grams of carbs or more per serving, says Franziska Spritzler, RD, author of The Low-Carb Dietitian's Guide to Health and Beauty.

Both the regular and reduced-sodium Campbell's versions include about 1 gram of dietary fiber, which doesn't break down into sugar. Some people on low-carb diets count total carbohydrates, while others count only digestible carbs, also known as net carbs. For those in the latter camp, the soup has about 18 to 19 grams of net carbs per serving.

Read more: Are Tomatoes Bad for Weight Loss?

Either way, that's a significant number of carbs for one meal already — but on its own, a single serving of tomato soup isn't much of a lunch or dinner. Most recipes range from about 80 to 160 calories per serving, which will likely leave you hungry shortly after eating. If you're beefing up your tomato soup with traditional toppings and sides, however, you're also adding more carbohydrates.

A half-cup of croutons, for example, adds about 10 grams of net carbs to your meal, according to the USDA. And if you're serving your soup with a sandwich, each slice of bread will add about 13 grams of net carbs.

If you're following a restrictive low-carb diet — like a ketogenic diet that sets a limit of 50 grams of carbohydrates a day or Phase 1 of the Atkins 20 Diet, which requires that you stick to 20 to 25 grams of net carbs per day — traditional tomato soup may not fit into your meal plan. A single serving of plain commercial tomato soup will take up a good portion (if not all) of your carb budget for the day, which means you'll have no allotment left for other healthy sources of carbs, like fibrous vegetables.

"Fresh tomatoes are fine when you're on a very low-carb diet like keto, but they're still higher in carbs than, say, leafy green vegetables," says Spritzler. "With tomato soup, the natural sugars and carbs are much more concentrated — so in general, you'll want to avoid it if you're really limiting your carbs."

Read more: Can You Eat Quinoa on a Low-Carb Diet?

If you're following a more liberal low-carb diet, though — one that allows 50 to 100 grams of carbohydrates a day, for example — you can easily include tomato soup in your meal plans. Just plan to forgo other starchy foods, like potatoes or white bread, and fill out your diet with low-carb veggies to avoid exceeding your carb allowance.

Your best bet for getting your tomato soup fix on a low-carb diet is to make your own at home. In addition to avoiding added sugar, you can increase the portion of heavy cream and reduce the portion of tomatoes, says Spritzler, which would lower the number of carbs per serving. But it would also increase total calories, which isn't ideal if you're trying to lose weight.

You can also forgo the dairy and make a delicious tomato soup with creamy coconut milk. (Both heavy cream and coconut milk have just half a gram of carbohydrates per tablespoon, but coconut milk has fewer calories and less saturated fat.) Use a food processor to blend 1/2 cup of crushed tomatoes with a tablespoon of coconut milk, a slice of onion and 1/2 cup of chicken broth, then heat it up for a soup that has just 8.5 grams of net carbs per serving, according to the USDA.

Read more: The Health Benefits of Coconut Milk

You can also ditch the grilled cheese and croutons and instead top your soup with Parmesan cheese and serve it with a fried egg on the side. Or make a low-carb "soup and sandwich" lunch by pairing your soup with lettuce wraps — sturdy romaine leaves stuffed with low-carb sandwich ingredients like turkey breast, spinach and mustard.

Additional reporting by Sylvie Tremblay.