The minute you begin exploring the keto / low-carb diet, you’ll learn that in order to follow it successfully, you need to significantly restrict your carbohydrate intake. But by how much? Some sources say you should limit your intake to 20 total carbs per day, while others say 20 net carbs per day. What’s the difference between total carbs and net carbs and why does it matter? We’ll explain everything you need to know here so you can decide the daily carb intake that’s right for you.
What’s the Purpose of Limiting Carbs?
To understand why you need to know about net and total carbs, it’s good to have a solid understanding of the role carb-limitation plays in the keto diet:
The entire goal of a ketogenic diet is to get and keep your body in a state of ketosis. This is where the body relies on fat for energy rather than carbs (sugar), and your ketone levels are at least 0.5 mmol/L when you test them (your blood glucose lowers significantly too, as sugar/carbs are known to raise blood sugar).
The only way to achieve ketosis is to drastically restrict your carb intake long enough so your body trains itself to produce ketones from stored and consumed fats and use them for energy. Once you’re in ketosis, the goal is to stay there and optimize its many benefits. The only way to do this is to continue to limit your carb intake.
But by how much exactly?
How Many Carbs Should You Eat per Day on a Keto Diet?
Fortunately, the amount of carbs you should eat on a keto diet is not arbitrary. In fact, it’s scientific, though there is some confusion due to nuances we explain here:
It’s widely agreed upon by physicians that people following a ketogenic diet for medically therapeutic reasons, such as cancer or epilepsy, should limit their total carb count to 20 grams of total carbs per day. Strict adherence ensures maximum benefit from higher ketone levels.
Here, “total carbs” is exactly what it sounds like—the total number of carbs consumed in one day (For success, it’s important to track your food intake, also known as macros or macronutrients, and carefully track your carb count using a tracker, since carbs can easily sneak into your diet.)
For the general population, there’s a consensus among experts that pretty much anyone can stay solidly in ketosis (i.e. maintain ketone levels of at least 0.5 mmol/L or more), if they consume 20 grams of net carbs per day.
Here’s where it can get confusing for keto newcomers: “Net carbs” are not the same as “total carbs.”
Net carbs are the total grams of carbohydrates in any given food minus its grams of fiber and sugar alcohols. (The sugar alcohols and fiber are subtracted because they are not digested by the body.)
Here’s the basic formula:
Net carbohydrates = total carbohydrates – fiber – sugar alcohols (if applicable).
When we say “fiber” we mean insoluble fiber and soluble fiber.
If you’re not familiar with sugar alcohols, you can learn about them here.
Here’s an example of the net carb calculation, using 1 cup of cauliflower rice:
1 cup of cauliflower rice contains 4.8 grams of total carbs and 3.2 grams of fiber. So, to get its net carbs, you subtract the fiber (3.2 grams) from the total carbs (4.8 grams), which leaves you with 1.6 grams of net carbs (i.e., 4.8 grams carbs – 3.2 grams fiber = 1.6 grams net carbs for 1 cup cauliflower rice).
If you’re following a keto diet for weight-loss or general health reasons, staying within 20 net carbs per day is the way to go. It’s easier to do, allows you far greater consumption of vegetables and other wholesome foods that contain carbohydrates, and, as we mentioned, still allows you to stay in ketosis.
Now let’s try an example of calculating net carbs with a food that contains sugar alcohols. There are many keto and low-carb products that utilize sugar-alcohol-based sweeteners to sweeten food products without adding carbs (or in the case of some sugar alcohols, adding minimal carbs). But there are also recipes that call for sugar alcohols. While there are many out there (maltitol, xylitol, sorbitol, etc.), we recommend erythritol sweetener, which, unlike some sugar alcohols, contains absolutely no carbs and doesn’t tend to affect blood-sugar levels. So, for this example, we’ll go with homemade keto whipped cream (2 cups heavy whipping cream and 2 teaspoons erythritol, whipped together).
Here, the whipping cream contains 32 grams of carbohydrates and 0 dietary fiber (or 32 total carbs), while the erythritol contains 8 grams of total carbs and 8 grams of fiber. So, the net carbs count is 32 – 0 + 8 – 8 = 32 carbs total for enough whipped cream to serve 16 people (thus 2 net carbs per serving).
Testing for Your Carb Edge or Bio-Individuality
Once you’re solidly in ketosis for three or more months, some people like to test their “carb edge,” to determine whether they can consume more than 20 net carbs per day and still stay in ketosis. You can do this by gradually increasing your daily carbohydrate consumption and testing your glucose and ketones daily to see if you get glucose spikes, or pushed out of ketosis by eating more carb foods, including carb-heavy veggies.
It’s also common to test yourself for bio-individuality, or how your unique body reacts to certain keto-friendly foods or processed foods. Some people get a glucose spike with certain sugar alcohols or dairy, for example. Testing your glucose and ketones before and after eating questionable foods allows you to discover if a food sensitivity is impeding your ability to stay in ketosis and achieve keto success.
The Final Word on the Difference Between Total Carbs vs Net Carbs
Total carbs are exactly that—the sum of all the carbs you eat in a day. Net carbs are calculated by taking your total carbs and subtracting fiber and sugar alcohols. You can make these calculations by reading food labels or calculating the macros of ingredients in the recipes you make.
Whether total carbs or net carb count is better for you to follow on a ketogenic diet depends on your goals. The bottom line: if you’re following a ketogenic diet for medically therapeutic reasons, it’s best to start at 20 TOTAL carbs per day. If you’re following the diet to battle obesity or insulin resistance (it helps stabilize insulin levels), for weight-loss, or preventative health measures, 20 NET carbs should do the trick.
Still, it’s a good idea to test your ketones along the way to find your carb edge and learn whether any food sensitivities are affecting your success. It’s also important to eat whole foods, avoid foods with added sugar (i.e. stay sugar-free), read nutrition facts and nutrition labels, and check with your primary care provider or dietitian before embarking on any diet.
Disclaimer: it’s always a good idea to consult with a dietitian and your primary care provider before starting any new diet.