All About Net Carbs

Apr 12, 2022Alex Brecher

Bariatric surgery patients have a strict diet. It’s usually high in protein, and that may be what you hear about most often. But the diet is usually low in carbs, too. What are carbohydrates, and how do they relate to net carbs? How can you best count your carbs and keep them low as you lose weight and try to eat healthy foods?

Understanding carbohydrates and knowing how to keep them in check is important for weight loss and health. This is what you should know about types of carbs, how to calculate net carbs, and net carbs in common foods.

Types of Carbohydrates in Foods

The main types of carbohydrates in foods are sugars, starches, and dietary fiber. Sugars and starches have different effects on your body compared to dietary fiber. When it comes to how to calculate net carbs, you’ll see this difference reflected.

Sugars are simple carbohydrates. Some foods are natural sources of sugar. Fruit, milk, legumes, and vegetables have different amounts of different types of natural sugar. Added sugars are put into foods to sweeten them or provide other functional properties. Desserts, sugar-sweetened beverages, condiments, candy, and flavored oatmeal and yogurt can have added sugars.

Starches are complex carbohydrates. They are long chains of sugars. Your body breaks down starches into sugars. Foods with lots of starches include starchy vegetables, such as potatoes, yams, and corn, breads, cereals, other grain products, and legumes, such as beans, split peas, and lentils.

Dietary fiber is another type of carbohydrate. Your body cannot break it down. That’s why fiber doesn’t contribute to spikes in blood sugar. It can actually reduce spikes in blood sugar that sugars and starches can cause. It can be added to processed foods, but it is naturally found only in plant foods, such as vegetables, whole grains, fruits, nuts, seeds, and legumes.

How to Calculate Net Carbs

Net carbs are also called the digestible or impact carbs. It’s not hard to learn how to calculate net carbs for a serving of food. You don’t have to worry about sugars and starches by themselves. Just look at total carbs, dietary fiber, and sugar alcohols.

Start by looking at the number of grams of total carbs in a serving of a specific food. Then look at the number of grams of dietary fiber in that same serving of that food. Subtract the number of grams of dietary fiber from the grams of total carbs, and you get the net carbs. Now you know how to calculate net carbs!

Examples of How to Calculate Net Carbs

These are some examples of how to calculate net carbs in some different types of foods with carbohydrates.

Non-Starchy Vegetables: Example Showing Net Carbs in Tomatoes

A cup of cherry tomatoes has 6 grams of total carbohydrates. Of those, 2 grams are from dietary fiber. That means there are 4 grams of net carbs in a cup of cherry tomatoes.

Tomatoes are a type of non-starchy vegetable. These vegetables are low in total carbohydrates and contain fiber. Their net carbs range from under 1 gram of net carbs per serving to about 4 per serving. Lettuce, other greens, onions, peppers, eggplants, zucchini, radishes, cucumbers, mushrooms, and broccoli are examples of other non-starchy vegetables.

Starchy Vegetables: Example Showing Net Carbs in Sweet Potato

Sweet potatoes are a starchy vegetable, which means they’re high in carbs. Each half-cup of mashed sweet potato has 29 grams of total carbs. It has 4 grams of fiber. Overall, the net carbs in sweet potatoes are 25 grams.

The net carbs in sweet potatoes are similar to the net carbs in starchy vegetables. These include peas, corn, potatoes, parsnips, yams, and acorn squash.

Fruit: Example Showing Net Carbs in Watermelon

Watermelon is so sweet and juicy. To calculate net carbs in watermelon, let’s start with total carbohydrates, which turn out to be 12 grams per cup of cubes. There is less than a gram of fiber, and the net carbs in watermelon are 11 grams.

The net carbs in watermelon are similar to the net carbs in some other fruit, such as 1 cup of cantaloupe or ½ cup of grapes. A small apple or pear has a similar amount. Bananas have more, and berries are lower in carbs.

Grains: Example Showing Net Carbs in Bread

Net carbs in bread can be high, especially if you tend to take a 2-slice serving. A 2-slice serving of whole-wheat bread has 25 grams of total carbs and 2 grams of fiber. The net carbs in bread are 23 grams for a 2-slice serving.

The net carbs in bread are similar on an ounce per ounce basis compared to net carbs in other bread products, such as bagels, pita bread, rolls, and English muffins. Still, it’s important to look at serving sizes. A large bagel has 66 total grams of carbohydrates and 63 grams of net carbs! Other grain products are similar. Zero net carb bread, though, is another story! Protein Pasta and Shirataki Rice and Pasta are other examples of low-carb grain swaps you can make.

Desserts: Example Showing Net Carbs in a Blueberry Muffin

For example, a blueberry muffin from a bakery can have 67 grams of total carbohydrates and 4 grams of dietary fiber. Subtract those 4 grams from 67, and you get 63 grams of net carbs.

Muffins, cookies, cake and other baked goods can have a lot of total carbs from sugars and starches, and they often have a lot of net carbs because they tend to be low in dietary fiber. Ice cream and other desserts are not as high in starch, but they have sugar and not much dietary fiber, leaving them high in net carbs.

Processed Foods: Example Showing Net Carbs in a Protein Bar

Let’s look at a BariatricPal 15-gram Protein and Fiber Bar - Fluffy Nutter. Each bar has 16 grams of total carbohydrates. That may sound like a lot - it’s the amount in a slice of bread! But, the Protein and Fiber Bar has 7 grams of dietary fiber, so you subtract that from 16 to get 9 grams of fiber. Take another look, and the bar also has 3 grams of sugar alcohols. Subtract those 3 grams from 9, and you end up with 6 grams of net carbs. That’s not bad for a satisfying protein snack that tastes great!

These are some other foods that may have sugar alcohols. Remember to subtract fiber and sugar alcohols from total carbs to get net carbs!

Protein Bars
Sugar-free ice cream
Sugar-free pudding
Low-Carb Chocolate Bars and Sugar-Free Candy, such as Gummies
Sugar-Free Jam
Sugar-Free Cakes and Cookies

Net Carbs Per Day for Bariatric Surgery Patients

You may be on a high-protein, low-carb diet after bariatric surgery. While you’re trying to increase protein intake to at least 65 to 75 grams per day, in many cases, you may also be trying to limit net carbs per day.

Ask your surgeon or nutritionist about your goal for daily net carbs. If you are on a keto or very-low-carb diet, your goal may be 20 or 30 grams a day. (In comparison, there are about 23 grams of net carbs in bread for a 2-slice serving). For a more moderate diet, your goal may be 100 to 120 grams of net carbs per day. (In comparison, there are about 50 grams of net carbs in sweet potatoes for a 1-cup serving, and 22 grams of net carbs in watermelon for a 1-cup serving).

Net Carbs and Glycemic Index

Using net carbs can help you lower the glycemic index of your diet. A food with a high glycemic index will spike your blood sugar more than a food with a lower glycemic index. Foods that are higher in fiber tend to have a lower glycemic index. By choosing a diet higher in fiber so that you can reduce the net carbs, your diet may end up being lower glycemic.

Total Carbs versus Net Carbs

Should you measure total or net carbohydrates? There are pros and cons of each approach. When you measure total carbohydrates, you only need to look at one number: the grams of total carbohydrates. That’s simpler than checking the total carbs and dietary fiber, and subtracting fiber from carbs.

On the other hand, using net carbs encourages you to look for foods that are higher in fiber content because fiber lowers the net carbs in a food. Dietary fiber has health benefits such as lowering blood sugar and cholesterol, and improving digestive health. Plus, looking for high-fiber foods often steers you towards healthier foods, such as vegetables, whole grains, and nuts.

Ways to Reduce Net Carbs

You can reduce net carbs while still including satisfying and delicious foods in your diet. First, learn the foods that are free from carbohydrates or very low in net carbs. These are some examples.

Meat, fish, poultry, eggs, and most shellfish are free from carbs.
Oils, butter, and other pure fats are naturally free from carbohydrates.
Nuts and seeds are very low in net carbs, and are mostly filled with fat, protein, and fiber.
Salad greens and other non-starchy vegetables are low in total carbohydrates and high in dietary fiber, leaving them low in net carbs.
Cheese is low in total and net carbs.

You can also look for products that are designed for low-carb diets and that can swap for other foods. These are some examples.

Zero net carb bread
Low-carb pasta
Protein Bars that are low in sugar or sugar-free
Low-Carb Protein Cereal
Low-Carb Pancake and Baking Mixes
Low-Carb Protein Chips and other Protein Snacks
Protein Pudding

Healthiest Carbs to Choose

You may be on a low-carb diet for a long time, so it’s good to choose the healthiest carbs to make the most of the ones you do choose to have. These are some examples of carbs that are high in fiber or other nutrients. When you eat them, you’ll be best off if you keep serving sizes in check and eat them with other healthy foods, especially with low-carb ones.

Type of Carb	Ideas for Using Them
1 ounce-equivalent of whole grains: such as ⅓ cup of cooked oatmeal, 1 slice of whole-grain bread, ½ whole grain English muffin, ⅓ cup of cooked whole-wheat pasta, quinoa, barley, or brown rice, ½ cup of shredded wheat, 3 cups of plain popcorn	Oatmeal with a soft-cooked egg and avocado slice Whole-grain bread with peanut butter Whole-wheat pasta tossed with olive oil, garlic, spinach, and parmesan cheese Grilled salmon and broccoli florets or asparagus tips served over brown rice or quinoa
1 serving of fruit: such as ¾ cup of berries or cut melon, 1 small apple or pear, 2 tangerines or apricots, ½ cup of pineapple	Fruit in cottage cheese with sunflower seeds Berries or clementine wedges in a salad Apple slices with cream cheese or blue cheese
½ cup of legumes: such as ½ cup of cooked beans, split peas, lentils, or tofu	Beans with melted cheddar cheese Split pea soup made with onions, celery, and chicken Three-bean salad with olive oil, vinegar, and green beans Greek salad with garbanzo beans, cooked chicken, feta cheese, lettuce, and vinaigrette with olive oil, thyme, oregano, and lemon juice or vinegar Lentil soup made with onions and carrots Tofu stir fried with vegetables and served with cauliflower rice
1 serving of starchy vegetable, such as ½ cup of peas, corn, or mashed potato or sweet potato, or ¾ cup of winter squash such as butternut, acorn, or kabocha squash	Baked sweet potato slices with olive oil and served with feta cheese and broccoli Meatloaf with peas, onion, and mushrooms Baked butternut squash stuffed with shredded chicken and diced onions and peppers

Carbohydrates can make or break your diet, and using net carbs can help you count them and select healthier ones. By sticking to proper serving sizes and choosing higher fiber sources of carbs, you can keep net carbs down and stay on your low-carb meal plan. That is a good way to hit your weight loss goals after bariatric surgery!

Tags: Net carbs, Types of carbohydrates, Understanding carbohydrates