Understanding Fiber, Carbohydrates, and Net Carbs
October 31, 2026 – Today is about Day 14 on my Keto Journey and I continue to feel great. I did slip up a little last night in having 4 Tablespoons of Coconut Whipped Cream and it felt like I was splurging. I woke at 3A this morning with a great deal of energy. Still not putting out a lot of urine. I am planning for another long fast this week (Sunday 6P to Tuesday Noon – 43 hours) and expect to put out a lot of urine Monday night.
I went for a long hike this morning on the Wiowash and was looking at the science behind my ‘Keto Bread’. It isn’t something I eat every day but my concern is that there is a great deal of misinformation out there on Fiber and Net Carbs. The reality is that not all fiber is the same. Some passes through completely undigested while other types of fiber is fermented in the gut. However, it doesn’t go through the same type of metabolism as other carbs.
Here is a brief overview I put together.
When following a low-carbohydrate or ketogenic diet, understanding the difference between total carbohydrates, fiber, and net carbs is important. Knowing how to calculate net carbs helps you make better food choices while staying within your daily carbohydrate goal.
1. What Are Carbohydrates?
Carbohydrates are one of the body’s primary sources of energy. They generally fall into three categories:
- Sugars: Simple carbohydrates that are quickly absorbed by the body.
- Starches: Complex carbohydrates that are broken down into glucose.
- Fiber: A type of carbohydrate that the body cannot fully digest.
2. Why Is Fiber Different?
Fiber is found in vegetables, nuts, seeds, and other plant-based foods. Unlike sugars and starches, most fiber is not digested and absorbed as glucose.
Fiber offers several benefits:
- Supports digestive and gut health.
- Helps regulate blood sugar.
- Promotes fullness and satisfaction.
- Supports healthy cholesterol levels.
This is why fiber is subtracted from total carbohydrates when calculating net carbs.
3. How Are Net Carbs Calculated?
Net carbs represent the carbohydrates that are generally digestible and available to affect blood sugar.
The basic formula is:
Net Carbs = Total Carbohydrates − Dietary Fiber
For example, if a food label shows:
- Total Carbohydrates: 12 grams
- Dietary Fiber: 7 grams
- Net Carbs: 5 grams
You count 5 grams toward your daily net carbohydrate allowance.
Note: Some products contain sugar alcohols, which may require additional consideration. Not all sugar alcohols have the same effect on blood sugar, so don’t automatically subtract all of them.
4. How to Calculate a 20–25 Gram Daily Carb Limit
If you are following a diet that limits carbohydrates to 20–25 grams per day, first determine whether your target refers to total carbs or net carbs. Many ketogenic diets use net carbs.
If your target is 20–25 grams of net carbs:
- Read the nutrition label.
- Find total carbohydrates.
- Subtract dietary fiber.
- Count the remaining net carbs toward your daily limit.
- Track your daily total to stay within your target.
Example Daily Carb Budget:
| Food | Net Carbs |
|---|---|
| Eggs | 1 g |
| Avocado | 2 g |
| Broccoli | 4 g |
| Spinach | 1 g |
| Almonds | 3 g |
| Other foods | 8 g |
| Daily Total | 19 g |
This leaves approximately 1–6 grams of flexibility, depending on whether your daily goal is 20 or 25 grams.
5. The Bottom Line
Don’t confuse total carbohydrates with net carbohydrates. Fiber is an important part of a healthy diet and generally does not count toward your net carb total.
When following a 20–25 gram net carb plan, focus on nutrient-dense, high-fiber vegetables, healthy fats, and quality protein.
Remember: Total Carbs − Fiber = Net Carbs.
Understanding this simple calculation makes reading food labels easier and helps you stay consistent with your nutritional goals.
