The ketogenic (keto) diet, characterized by a low-carbohydrate, high-fat intake, has gained popularity as a weight-loss strategy and a method for managing certain medical conditions. The central premise of the keto diet is simple: limit your carbohydrate intake to the point that your body prefers to use fat (and the ketones produced by metabolizing fat) as a primary source of energy. For the average person, this usually means 50 grams or fewer net carbs per day. A key aspect of this dietary approach is understanding and calculating carbohydrate intake, particularly "net carbs." This article serves as a comprehensive guide to keto carb counting, explaining what net carbs are, how to calculate them, and why they matter for those following a ketogenic lifestyle.
Understanding Net Carbs
"Net carbs" refers to carbs that are absorbed by your body. Net carbs are sometimes referred to as digestible or impact carbs. The terms refer to carbs that are absorbed by the body, including both simple and complex carbs. Simple carbs contain one or two sugar units linked together and are found in foods like fruits, vegetables, milk, sugar, honey and syrup. Complex carbs contain many sugar units linked together and are found in grains and starchy vegetables like potatoes.
Unlike net carbs - which are absorbed through the small intestine and sent to the bloodstream to raise blood sugar - fiber and sugar alcohols buy a one-way ticket to the large intestine. Once they get there, they’re either fed to gut bacteria (via fermentation) or pass straight on through. Thus, dietary fiber and sugar alcohols have minimal calories and blood sugar effects.
On food labels, you'll typically find "total carbs," which include all types of carbohydrates, including fiber and sugar alcohols. However, not all carbohydrates have the same impact on blood sugar levels. Fiber, for instance, is a type of carbohydrate that the body cannot digest and so cannot transform into glucose to store and use for energy. Similarly, sugar alcohols are not fully absorbed by the body. Therefore, net carbs represent the carbohydrates that the body can actually use for energy, influencing blood sugar and insulin levels.
The Controversy Surrounding Net Carbs
Whether to count net or total carbs is a controversial topic within the low-carb community. For starters, the term “net carbs” continues to be disputed amongst nutrition experts. The Food and Drug Administration (FDA) does not recognize the term “net carbs.” The FDA instead recommends using the total carbohydrates listed on the nutrition label. In addition, due to conflicting and outdated information, figuring out how to calculate net carbs can be confusing.
Read also: Interpreting Keto-Mojo Results
Calculating Net Carbs
To determine the net carbs in a food, you subtract the grams of fiber and a portion of the sugar alcohols from the total carbohydrate count. Here's the formula:
Net carbs = Total carbohydrates - Fiber - ½ (Sugar alcohols)
Calculating Net Carbs in Whole Foods
Whole foods contain naturally occurring fiber. Therefore, you can simply subtract the fiber from the total carbs to get the net carbs. The USDA Food Composition Databases provides complete nutrition information on thousands of foods, including carbs and fiber. For example, a medium avocado contains 17.1 grams of total carbs, 13.5 grams of which is fiber. So 17.1 grams of total carbs - 13.5 grams of fiber = 3.6 grams of net carbs.
Calculating Net Carbs in Processed Foods
To calculate the net carbs in a packaged product, the more information you have, the better. Generally speaking, half of the carbs from sugar alcohols can be subtracted from the total carbs listed on the nutrition label. Erythritol is an exception. If it’s the only sugar alcohol in the ingredients list, its carbs can be completely subtracted from the total carbs. This value may be different than the number of net carbs stated on the product label, since many companies subtract all fiber and sugar alcohol carbs when calculating net carbs. For example, a maltitol-sweetened Atkins bar label states that it contains 3 grams of net carbs. However, when subtracting only half the carbs from sugar alcohols, the net carb value is 8.5 grams: 23 grams of total carbs - 9 grams of fiber - 11 grams sugar alcohols (11 grams X 0.5 = 5.5 grams) = 8.5 grams of net carbs.
Fiber: The Indigestible Carb
Fiber is a unique form of carbs in terms of its digestion and effects on your body. Unlike starch and sugar, naturally occurring fiber isn’t absorbed in your small intestine. This is because the links between sugar units can’t be broken down by the enzymes in your digestive tract. Therefore, fiber passes directly into the colon. However, its fate after that depends on what type of fiber it is. There are two broad categories of fiber: insoluble and soluble. About two-thirds of the fiber you eat is insoluble, while the other third is soluble. Insoluble fiber does not dissolve in water. It creates a bulkier stool and can help prevent constipation. This type of fiber leaves the colon unchanged, provides no calories and has no effect on blood sugar or insulin levels.
Sugar Alcohols: A Partial Subtraction
Sugar alcohols are processed similarly to fiber, with a few important differences. Many sugar alcohols are only partially absorbed in the small intestine, and there is a lot of variation among different types. Researchers report the small intestine absorbs 2-90% of sugar alcohols. However, some are only briefly absorbed into the bloodstream and then excreted in urine. In addition, these sugar alcohols can have varying effects on blood sugar and insulin levels, although all are considerably lower than sugar.
Read also: Diet Plan: No Sugar, Carbs, Dairy
Here is a list of the glycemic and insulin indexes for the most common sugar alcohols:
- Erythritol: Glycemic index 0, insulin index 2
- Isomalt: Glycemic index 9, insulin index 6
- Maltitol: Glycemic index 35, insulin index 27
- Sorbitol: Glycemic index 9, insulin index 11
- Xylitol: Glycemic index 13, insulin index 11
Overall, sugar alcohols don’t seem to have a major effect on blood sugar and insulin levels, but individual responses may vary, especially among those with diabetes or prediabetes.
Why Track Net Carbs on Keto?
The central premise of the keto diet is simple: limit your carbohydrate intake to the point that your body prefers to use fat (and the ketones produced by metabolizing fat) as a primary source of energy. For the average person, this usually means 50 grams or fewer net carbs per day. Yes, people bat an eye when I say that. But the key word is net. Most fiber passes through the body undigested, and most sugar alcohols feed gut bacteria in your large intestine. Neither are converted to glucose for energy. That’s why net carbs - which don’t include fiber and most sugar alcohols - are the only carbs that count toward your carb intake limit. This leaves a lot of room for veggies (and even some fruit!), depending on which ones you incorporate in your diet.
Advantages of Using Net Carbs vs. Total Carbs
There are three main reasons why calculating net carbs is worth your time:
More dietary flexibility
All plant matter contains carbs as sugar, starch, or fiber. So when you significantly restrict your carbohydrate intake, you may lose access to many food groups. Paying attention to net carbs will help you be less restrictive with your food choices. You can include a wide variety of fibrous vegetables, and even a few fruits like blueberries, raspberries, and avocados. These aren’t just benefits for your health, but also for your sanity. It provides enough variety to keep your taste buds happy. This doesn’t mean that a carnivore-style keto diet (with close to 0 total carbs) has no place. But for most people, more flexibility is a good thing. And minding net carbs add a bit of flex.
Read also: Is the Carnivore Diet Right for You?
More micronutrients
Fiber-rich plants are some of the most nutrient-dense foods on the planet. For example, a typical serving of broccoli (1 cup) contains 6 grams of carbs, 3 of which are fiber. Other plants have similarly robust profiles, and it’s hard to get enough micronutrients when you’re relying on total carbs to navigate your diet.
More fiber
This is probably obvious by now, but using total carbs instead of net carbs will make you miss out on a lot of fiber too. Dietary fiber is important to keep digestion running smoothly and to feed your gut microbiome. You may think of gut bacteria as mere passengers, but they’re an essential part of our biology. Fiber is what feeds that microbiome, helping to produce anti-inflammatory compounds like butyrate. Butyrate fuels colonic cells and may protect against colon cancer. Higher fiber intakes have also been linked to heart disease prevention. those consuming the least) had about a 20% lower chance of dying from heart disease. Using net carbs brings more fiber into a low-carb diet. We like that!
How to Track Net Carbs
If you enjoy tracking your intake manually, feel free to use this equation with every food you eat:
Net carbs = total carbs - fiber - ½ sugar alcohols
But if you’re like me, you may want to automate this process. That’s what macro tracking apps are for! You don’t need to track net carbs forever, either. Getting a sense for your typical meals can make eating more intuitive and less calculated.
Plus, stick to these few rules, and you can pretty much forget about tracking carbs entirely:
- Eat mostly unprocessed foods
- Use your carb allowance for green-ish vegetables that grow above ground, and some low fructose fruit like blueberries or avocados
- Avoid sugar alcohols for simplicity
When you follow the rules above, it’s pretty difficult to eat more than 50 grams of net carbs in a day. Plus, you’ll get the added benefit of maximizing nutrient density. Log your meals for a few days, get a feel for it, and go on autopilot.
Finding Carb Information
You can find how many carbs foods have by reading food labels. If a product doesn’t have a food label, such as a whole piece of fruit or a vegetable, there are apps and other tools available to help you calculate. Department of Agriculture’s Food Composition Database has nutrition information for thousands of foods in a searchable format. The good news is, the longer you practice carb counting, the more you'll remember the carb content of the foods you commonly eat.
There are two items on the nutrition facts label that you’ll want to pay attention to when carb counting:
- Serving size. The serving size refers to how much a person usually eats or drinks, and all the information on the label is about this specific amount of food. If you eat more, you will need to account for the additional nutrients. For example, eating two or three servings of something, means you will need to double or triple the amount of grams of carbs (and all other nutrients) on the label in your calculations.
- Grams of total carbohydrate. This number includes all carbs: sugar, starch and fiber. That’s right: You don’t have to worry about adding on grams of added sugars-they’re included in the number of total carbs! The added sugars and other bullets below the total carbs listing are included to provide more information about what’s in the food that you are eating. And while you don’t need to worry about adding added sugars when it comes to counting carbs, you should still aim to minimize the amount of added sugar in the foods you eat.
Keto-Friendly Foods and Net Carbs
A person following a keto diet eats foods with high levels of fats and very low levels of carbohydrates. The diet excludes a wide range of foods, including some fruits and vegetables, as well as bread, beans, and legumes.
Fresh Meat and Fish
These foods tend to make up a large part of a keto diet, as they contain no carbohydrates but can be good sources of some nutrients. Some examples of fresh meat and fish included in the keto diet include:
- turkey
- pork
- chicken
- lamb
- beef
- veal
- venison
- shellfish
- tuna
- cod
- salmon
- sardines
Dairy
Cheese tends to be low in carbs but high in fat, making it a good choice for keto diets. For example, 100 g of cheddar cheese has 2.44 g of carbs and 34 g of fat.
Vegetables
Fruits are an important part of any diet, as they are rich in vitamins and minerals. However, some fruits are high in carbs, so researching - including checking labels - is key.
Nuts and Seeds
Wheat-based products, such as rice, pasta, and cereals, are high in carbs. Therefore, a person following a keto diet should limit them.
The Keto Diet: More Than Just Carbs
The ketogenic (keto) diet limits carbohydrates and replaces them with fats, putting the body into a state of ketosis. To stay in ketosis, a person requires up to 50 grams (g) of carbs per day. According to a 2018 review of the different types of keto diet, a person should consume up to 50 grams (g) of carbohydrates per day to stay in ketosis.
The average recommended daily protein intake for a person assigned female at birth following a keto dietary plan is 46 g, and for a person assigned male at birth, it is 56 g. In addition to low carbs, the keto diet involves moderate amounts of protein, as excess protein can prevent ketosis.
However, different keto diets allow for different amounts of carbs, protein, and fat:
- Standard ketogenic diet: Overall, 70% of a person’s intake is fat, 20% is protein, and 10% is carbs.
- Cyclical ketogenic diet: There is a cycle of 5 low carb days and 2 high carb days.
- Targeted ketogenic diet: A person can eat more carbs around high intensity workouts.
- High protein ketogenic diet: Overall, 60% of a person’s intake is fat, 35% is protein, and 5% is carbs.
The standard keto diet has been the subject of most research, and experts who recommend ketogenic diets tend to be more likely to recommend this type.
Understanding Ketosis
When a person consumes carbohydrates, the body turns those carbs into sugar, which cells use for energy. Significantly limiting carb intake causes the body to burn fat instead of carbs for energy, causing glucose levels to drop. This forces the body to produce ketones, acids that appear in the blood and urine when the body burns fat. When the body uses fat as energy and releases ketones, this is called ketosis. During ketosis, the body also produces less insulin and stores less fat as a result.
The keto diet may help support weight loss, if this is a goal, by burning fat for energy. It may also help manage type 2 diabetes.
Potential Benefits and Risks
The ketogenic diet has been shown to produce beneficial metabolic changes in the short-term. Along with weight loss, health parameters associated with carrying excess weight have improved, such as insulin resistance, high blood pressure, and elevated cholesterol and triglycerides. There is also growing interest in the use of low-carbohydrate diets, including the ketogenic diet, for type 2 diabetes.
However, following a very high-fat diet may be challenging to maintain. Some negative side effects of a long-term ketogenic diet have been suggested, including increased risk of kidney stones and osteoporosis, and increased blood levels of uric acid (a risk factor for gout). Possible nutrient deficiencies may arise if a variety of recommended foods on the ketogenic diet are not included. It is important to not solely focus on eating high-fat foods, but to include a daily variety of the allowed meats, fish, vegetables, fruits, nuts, and seeds to ensure adequate intakes of fiber, B vitamins, and minerals (iron, magnesium, zinc)-nutrients typically found in foods like whole grains that are restricted from the diet.
Available research on the ketogenic diet for weight loss is still limited. Most of the studies so far have had a small number of participants, were short-term (12 weeks or less), and did not include control groups. A ketogenic diet has been shown to provide short-term benefits in some people including weight loss and improvements in total cholesterol, blood sugar, and blood pressure. However, these effects after one year when compared with the effects of conventional weight loss diets are not significantly different. Eliminating several food groups and the potential for unpleasant symptoms may make compliance difficult. An emphasis on foods high in saturated fat also counters recommendations from the Dietary Guidelines for Americans and the American Heart Association and may have adverse effects on blood LDL cholesterol.
Important Considerations
Keeping the keto diet sustainable can be challenging because it is very restrictive. A person may become bored by what they can eat. Moreover, the diet can cause side effects.
Gradual Changes
It can help to ease into the diet gradually. For instance, a person might stop eating one type of food at a time, such as bread or juice that is high in carbs and sugar.
Whole, Unprocessed Foods
Aim to consume carbs from whole, unprocessed foods to benefit from their vitamins and minerals.
Monitoring
For people following the keto diet, regular health monitoring is important to check whether the diet is having any effects on the heart. For people with diabetes, it is also important to monitor for hypoglycemia (low blood sugar).
Overall, it is important for people to check with a doctor before making any significant changes to their diet, such as switching to a ketogenic diet.
Carb Counting for Diabetes Management
Carbohydrates -- also called carbs -- are an important energy source for your body. Your digestive system can break them down quickly. They're converted into glucose, or blood sugar. Your body can use glucose right away for energy or store it for later.
If you're trying to stick to a certain diet or lose weight, you may want to restrict your carb intake and make sure you're selecting the healthiest ones. You also may need to limit carbs if you're managing diabetes.
Counting carbs is one way to monitor how many you consume. Carbs are typically measured in grams, which indicates weight.
If you don't have diabetes, your blood sugar level will rise after you eat carbs, but your body's insulin will keep your blood sugar from going too high. However, when you have diabetes, your blood sugar can spike too high after you eat carbs because there's an issue with your insulin response.
- Type 1 diabetes: Your pancreas isn't making insulin. To keep your blood sugar levels stable, you need to take insulin. It's important to know how many carbs you're consuming to be able to strike the right balance.
- Type 2 diabetes: You're resistant to the insulin your body makes, and you don't have enough in your body to keep your blood glucose at the right level. You need to keep an eye on your carbs as well.
How to Count Carbs
Carb counting at its most basic level involves counting the number of grams of carbohydrate in a meal and matching that to your dose of insulin.
If you take mealtime insulin, that means first accounting for each carbohydrate gram you eat and dosing mealtime insulin based on that count. You will use what's known as an insulin-to-carb ratio to calculate how much insulin you should take in order to manage your blood sugars after eating. This advanced form of carb counting is recommended for people on intensive insulin therapy by shots or pump, such as those with type 1 and some people with type 2.
While people with type 2 diabetes who don't take mealtime insulin may not need detailed carb counting to keep their blood sugars in line, some prefer to do it. While some choose to stick with traditional carb counting, there are others who do a more basic version of carb counting based on "carbohydrate choices," where one “choice” contains about 15 grams of carb. Still others use the Diabetes Plate Method to eat a reasonable portion of carb-containing foods at each meal by limiting whole grains, starchy vegetables, fruits or dairy to a quarter of the plate.
So, there are a few ways to go about it and it’s really about personal preference, but remember that the best carb counting method for you is the one that addresses your medication and lifestyle needs. A registered dietitian nutritionist (RDN/RD) or Certified Diabetes Care and Education Specialist (CDCES) can help you figure out what works best for you.
How Many Carbs Should You Eat?
As for the ideal number of carbs per meal, there's no magic number. How much carbohydrate each person needs is in large part determined by your body size and activity level. Appetite and hunger also play a role.