How to Check if Something Is Low Carb

December 6, 2025 •

4 min read

According to the CDC, approximately 12.3% of U.S. adults reported being on a low-carbohydrate diet in 2018, underscoring its widespread popularity. Navigating this dietary style requires knowing precisely how to check if something is low carb, a skill that goes beyond just glancing at a product's front packaging. This guide will teach you how to decode nutrition labels and spot hidden sources of carbohydrates to ensure your food choices align with your low-carb goals.

Quick Summary

This guide provides practical steps for identifying low-carb foods by thoroughly explaining how to read nutrition labels. It details how to calculate net carbs, recognize hidden sugars and starches in ingredient lists, and compare packaged products effectively. The article also offers tips for discerning genuinely low-carb products from misleading marketing claims.

Key Points

Serving Size is Key: Always check the serving size first, as all nutritional values on the label are based on this amount.
Total vs. Net Carbs: Focus on net carbs, calculated by subtracting fiber and sugar alcohols from the total carbohydrate count.
Decode the Ingredient List: Be on the lookout for hidden carbs like corn syrup, maltodextrin, and refined flours, which are listed in descending order by weight.
Beware of Marketing Claims: Phrases like "sugar-free" or "low-fat" on packaging can be misleading; the nutrition label and ingredient list tell the true story.
Prioritize Whole Foods: The most reliable low-carb options are unprocessed foods like meat, fish, eggs, and non-starchy vegetables, which require no label checking.
Understand Sugar Alcohols: Not all sugar alcohols are created equal; some, like maltitol, can have a greater effect on blood sugar than others, like erythritol.
Double-Check in Different Countries: Be aware of different labeling standards, such as the UK where fiber is listed separately and doesn't need to be subtracted.

Understanding the Nutrition Facts Label

Mastering the Nutrition Facts label is the single most important skill for anyone following a low-carb diet. This small box holds all the critical information you need, but you must know where to look. Ignoring the serving size is a common mistake that can completely derail your carb counting efforts.

Step-by-Step Label Reading

Start with Serving Information: Always begin by checking the "Servings Per Container" and "Serving Size". The nutritional data is based on a single serving, so if you eat the whole package, you'll need to multiply all values accordingly.
Check Total Carbohydrate: This is the headline number you need to focus on. It includes all types of carbohydrates—fiber, sugar, and starch.
Identify Dietary Fiber: Fiber is a type of carbohydrate that your body cannot fully digest, so it does not raise your blood sugar. In the U.S., you subtract dietary fiber from the total carbs to get the "net carb" count, which is the number most relevant for low-carb diets.
Subtract Sugar Alcohols (with caution): Sugar alcohols (e.g., erythritol, xylitol) are another category of carbs that have a minimal impact on blood sugar. You can also subtract these, but be aware that some, like maltitol, are partially absorbed and can affect blood sugar more significantly. Always subtract sugar alcohols from the total carb count to get the net carb total.

Calculating Net Carbs: A Critical Skill

Calculating net carbs is crucial for accurately tracking your carbohydrate intake on a low-carb diet, especially for packaged foods. The formula is straightforward but requires careful attention to detail.

$Net \ Carbs = Total \ Carbs - Dietary \ Fiber - Sugar \ Alcohols$

It's important to remember that some countries, like those in the UK, list fiber separately on nutrition labels, so no subtraction is necessary. However, in the US, fiber is included in the total carbohydrate count, making this calculation essential.

Spotting Hidden Carbs and Sugars

Food manufacturers often use clever marketing and ingredient lists to obscure the true carb content of a product. Words like "sugar-free" or "low-fat" do not guarantee a product is low-carb, and many contain hidden sweeteners and fillers.

Common Hidden Carbohydrate Sources

Corn Syrup and Dextrose: These are simple sugars that will spike blood sugar.
Maltodextrin: A fast-digesting carb often used as a thickener and filler.
Refined Flours: Ingredients like wheat flour, potato flour, and rice flour are high in simple carbs.
Fruit Juice Concentrates: A concentrated form of sugar used to sweeten products.

A Comparison of High-Carb vs. Low-Carb Foods

Knowing what to look for can be simplified by comparing typical high-carb and low-carb choices. This table highlights common food categories and how to make a lower-carb substitution.


Food Category	High-Carb Example	Low-Carb Alternative
Grains	White Rice	Cauliflower Rice
Pasta	Traditional Wheat Pasta	Zucchini Noodles or Shirataki Noodles
Starchy Vegetables	Potatoes	Broccoli or Cauliflower
Snacks	Potato Chips	Pork Rinds or Cheese Crisps
Sweeteners	Sugar or Honey	Stevia or Monk Fruit Sweetener
Dairy	Skim Milk	Heavy Cream or Almond Milk
Baked Goods	Standard Bread	Low-Carb or Almond Flour Bread

The Role of Ingredients and Context

Beyond the numbers on the nutrition panel, the ingredient list provides additional context. Ingredients are listed in descending order by weight, so the first few items are the most abundant. If sugar, flour, or other starchy items are at the top, the product is likely not low-carb, regardless of what the front of the package says. Always prioritize whole, unprocessed foods like meat, fish, eggs, and non-starchy vegetables, which are naturally low in carbohydrates and don't require label scrutiny. Processed "low-carb" snacks often contain additives and chemicals that may not align with overall health goals. Therefore, a product with a short, recognizable ingredient list is generally a better choice.

Making the Best Choices

Following these steps can help you successfully navigate the grocery store aisles and stick to your low-carb diet. Reading labels for serving size and net carbs, recognizing hidden ingredients, and choosing whole foods are the most effective strategies. While packaged foods can be a convenient option, remember that fresh, unprocessed ingredients are the most reliable way to maintain a truly low-carb lifestyle. Armed with this knowledge, you can make informed decisions and achieve your health objectives.

Conclusion

Successfully navigating a low-carb diet depends on your ability to accurately assess the carbohydrate content of foods. By meticulously reading nutrition labels, correctly calculating net carbs, and identifying hidden sources of sugar and starch, you can avoid common pitfalls and make truly informed choices. Prioritizing whole, unprocessed foods and being wary of marketing claims will serve you best on your low-carb journey. Becoming a proficient label reader is your key to sustained success and better health.

Frequently Asked Questions

Total carbs are the total amount of carbohydrates in a food, including fiber and sugar alcohols. Net carbs are the amount of carbs that your body can fully digest and absorb. You calculate net carbs by subtracting fiber and sugar alcohols from the total carb count.

To calculate net carbs, take the 'Total Carbohydrate' number listed on the nutrition label and subtract the 'Dietary Fiber'. If the product contains sugar alcohols, you also subtract those from the total. The formula is: Total Carbs - Fiber - Sugar Alcohols = Net Carbs.

You should approach 'sugar-free' claims with caution. Many products use alternative sweeteners like sugar alcohols, which can sometimes impact blood sugar. Always check the full nutrition label and ingredient list to understand the actual carbohydrate content and type of sweetener used.

Common hidden carbs include corn syrup, maltodextrin, refined flours (like wheat or rice flour), and fruit juice concentrates. Always read the ingredient list, especially the first few items, as they make up the largest portion of the product.

The serving size is crucial because all nutritional information, including the carb count, is based on that specific amount. If you eat two servings, you must double the carb count and all other nutrients to get an accurate total.

While fiber is technically a carbohydrate, your body doesn't digest and absorb it in the same way as other carbs, so it typically does not raise blood sugar. Therefore, you subtract it when calculating net carbs, which are the carbs that impact your blood sugar levels.

Ingredients on a food label are listed in descending order by weight, meaning the most prevalent ingredient is listed first. This helps you quickly determine if a product is primarily made of high-carb items like sugar or flour.