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Confused about how to calculate net carbs in food? You’re not alone. You need to consider how fiber and sugar alcohols will impact your blood sugar levels.
Why count carbs? Some diabetics have to in order to keep blood sugar levels in check. Other people calculate net carbs to stay on the low-carb bandwagon.
Of all the food trends that have come and gone, perhaps the most egregious to human health was the low-fat craze. As people went low-fat, they upped the carbs.
The result: rates of obesity and other metabolic disorders and other chronic diseases soared.
Some people take low carb very seriously. In an effort to stay low carb, some people learn how to calculate net carbs in food. For diabetics, especially those with type 1, counting the effective carbs is a vital tool for maintaining proper blood glucose levels. While for non-diabetics, counting carbs is used for preventing weight gain.
Competitive bodybuilders count carbs to maximize muscle definition.
Net carb food labeling
Whatever the reason people calculate net carbs in food is, more food brands are using the net carbs label. The FDA does not require the net carbs label. Nutrition labels need to include total carbs, total dietary fiber and sugars.
If the FDA doesn’t require total net carbs, then why label it? If, say a loaf of bread contains 20 grams of total carbs per slice but also has 15 grams of fiber per slice, the net carbs would be only 5 grams. That’s a big selling point for people looking for low carb foods.
But the equation for how to calculate net carbs is more complicated than total carbs minus fiber. Most companies calculate net carbs by taking total carbs minus grams of fiber, glycerin and sugar alcohols.
Perhaps the FDA should—and eventually will—regulate how net carbs are calculated. That’s because companies don’t always get the total right.
While sugar alcohols and fiber do affect blood sugar much less than starches and table sugar, it still has an effect on blood glucose. That’s why diabetics sometimes include part of the fiber and sugar alcohols when determining the net effective carbs.
Counting net carbs might seem too much of a burden for some people. But learning how to calculate the net carbs in the foods you eat can be beneficial for health.
In general, the slower a food raises your blood sugar level, the better off you’ll be. Eating carbs that rapidly raises blood glucose, ultimately leads to cravings and crashes. After all, what goes up must go down. And what quickly goes up tends to fall fast.
How to calculate carbs in food
If you’re eating foods that are truly all-natural, or at most, minimally processed, the simple above formula will be all you need: take the total grams of carbs and subtract the amount of fiber grams from the total. If a whole wheat pasta serving contains 45 grams of total carbs but there are 20 grams of fiber, the total net carbs would be 25 grams.
But this formula isn’t entirely accurate. That’s because fiber doesn’t necessarily have zero impact on blood glucose. According to Prevention, it takes about 10 grams of fiber to reduce blood sugar levels by 25%. In other words, just because you’re getting some fiber in a food does not mean that the food won’t raise blood sugar.
For a more accurate formula for how to count carbs in food, use this per serving model:
Total carbohydrates minus (-) total grams of fiber (include both soluble and insoluble if it’s listed) – minus 1/2 the number of grams of sugar alcohols (if there are at least 5 grams of sugar alcohols listed in total carbohydrates) = net carbs
The exception to the rule for the above is usually erythritol. Of all the sugar alcohols, erythritol has been shown to have little to no impact on blood sugar.
How many net carbs should I eat?
The amount of carbs or net carbs you consume depends on what your goal is. If you’re following a medically supervised ketogenic diet to reduce seizures, you’ll want to keep total carbs to 50 maximum. (You can use this keto calculator to count net carbs.)
Some people follow the Ketogenic diet not out of necessity for medical reasons, but just to stay healthy. Staying under 20 grams of net carbs per day should keep you in a state of ketosis, if that’s your goal. When you’re in ketosis, you’re burning ketones, or stored body fat for energy rather than carbs as the primary fuel source.
If you want to stay on a low carb diet, but not for medical reasons or weight loss, you can have up to 50 grams of net carbs (give or take). Knowing how to calculate net carbs in your food can help you stick with food that isn’t going to cause unwanted insulin spikes.
Think counting carbs is too cumbersome? Then just eat lots of fresh vegetables and some fruit as your main source of carbs. If you put weight on easily, limit or eliminate your intake of all grains. But if you want to feel full and avoid cravings for junk carbs, do have some slower-burning fiber rich foods.
How to calculate net carbs sugar alcohol
The mega popular low carb-high fat Atkins Diet contains lots of products with sugar alcohols. These low carb foods make it easy for followers of this and other low carb diets to avoid foods that spike blood sugar.
There are sugar alcohols that naturally occur in fruits. But when you see sugar alcohol on a nutrition label, chances are it’s a manufactured sugar alcohol. Food scientists make sugar alcohols from other sources of sugar, including sucrose and glucose.
Examples of sugar alcohols you’d most often see on a low carb food product nutrition label include erythritol, glycerin, xylitol and maltitol. Remember that erythritol has little to no impact for most people.
The advantage of these sugar alcohols is that they don’t get fully absorbed in the digestive tract. Because of this, they don’t raise blood sugar levels as much as fructose.
For those who want to know how to calculate net carbs quickly, they can use the simple but less accurate formula of subtracting grams of sugar alcohols from total grams of carbs. But this method, remember, isn’t 100% accurate. Sugar alcohols do have the potential to raise blood sugar. That’s why some people who are technical about counting net carbs take the total sugar alcohol and divide by half before subtracting from total net carbs.
As an example, if total carbs equals 50 and sugar alcohols are 10, you can subtract 5 grams of carbs.
It might take a degree in biochemistry to get a 100% accurate analysis of net carbs. That’s why most people usually just use the total net carbs minus fiber and sugar alcohol formula.