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Short Summary
Main recommendation: To make a low-carb or keto diet work reliably, count total grams of carbohydrate rather than net carbs, starting around 20 grams of total carbs per day. Dr. Eric Westman says sugar alcohols, artificial sweeteners, and fiber should not be automatically subtracted, since individual responses vary and the science is incomplete.
Key Points
- Dr. Westman says that historically, keto diets used total grams of carbohydrate, and net-carb subtraction only became common about 10 years ago.
- He describes counting total carbs as the strictest method, recommended for people who want the diet to work the first time or have a tougher metabolism.
- Sugar alcohols such as erythritol may not affect blood sugar uniformly, so marketing claims that they can be ignored are, in his view, too simple.
- He says switching from net carbs to total carbs can restart progress for people who have stalled.
- Foods are not forbidden on a low-carb diet; the issue is how many carbs they contain, so portion reduction (e.g., half an avocado) is the common approach.
Details Worth Noting
- Concrete instructions:
- Start with about 20 grams of total carbohydrate per day, counting the total number after "Total Carbohydrate" on the label without subtracting fiber or sugar alcohols.
- If you want to attempt net carbs later, a rough rule of thumb he gives is that net carbs are about half of total carbs, so 20 net carbs roughly equals 40 total carbs.
- Count fiber supplements such as psyllium husk or Metamucil as carbs.
- If progress stops while using net carbs, switch to total carbs and watch whether progress resumes.
- To reduce carbs from a high-carb food like avocado, eat half of it.
- Fruit limits depend on individual metabolism; for the best chance of initial success, he would avoid berries entirely.
- Dr. Westman notes that he has seen no solid data on sugar alcohols causing an insulin response, though he has heard anecdotal reports.
- Products marketed under "net carb" labels may not be suitable for everyone, and avoiding them for a period may be necessary.
- Carb tolerance varies by individual, so some people can eat more carbs than others.
Bottom Line
Counting total carbs is the most conservative path, and net-carb approaches should be tried only after you know how your body responds, with a switch back to total carbs if results stall.
