9 Bad Keto Food Ingredients to Avoid
Summary
As the market for keto-branded snacks and foods expands rapidly, many products contain ingredients that are misleadingly labeled as keto-friendly. Dr. Berg identifies nine specific ingredients that can spike blood sugar, cause digestive issues, or otherwise undermine a ketogenic diet. Reading ingredient labels carefully is essential for staying on track.
Key Takeaways
- Corn fiber is GMO-derived and commonly causes excessive gas
- Maltodextrin has a glycemic index of over 100 — higher than table sugar (which ranks around 65) — meaning it converts to glucose faster than sugar itself
- Dextran, dextrose, and polydextrose are synthetic sugars that have no place in a true keto food
- Maltitol, a common sugar alcohol, ranks high on the glycemic index despite appearing in “keto” products
- Soy protein isolate is typically GMO-sourced and should be avoided
- Splenda (sucralose) and other artificial sweeteners like aspartame are flagged as problematic additives
- Tapioca starch converts to sugar quickly and is not keto-compatible
- Other sugar alcohols beyond maltitol may cause bloating and digestive discomfort even if they don’t spike blood sugar
Details
High-Glycemic Imposters
The most concerning ingredient highlighted is maltodextrin, which carries a glycemic index exceeding 100. For context, pure glucose sits at 100 and table sugar at approximately 65, making maltodextrin one of the fastest-acting blood sugar-spiking ingredients available. Its presence in products marketed as keto-friendly is described as particularly surprising and misleading.
Dextran, dextrose, and polydextrose fall into a similar category — all are forms of synthetic or processed sugar that would disrupt ketosis by triggering an insulin response.
Tapioca starch is another hidden culprit, rapidly breaking down into glucose in the body despite sometimes appearing in “low-carb” labeled products.
The Maltitol Problem
Maltitol is a sugar alcohol frequently used in keto snacks as a sugar substitute. Unlike lower-impact sugar alcohols such as erythritol, maltitol has a notably high glycemic index and can raise blood sugar levels, making it unsuitable for a strict ketogenic approach.
GMO and Additive Concerns
- Corn fiber is noted as being GMO and a common source of gastrointestinal issues, particularly gas
- Soy protein isolate is also identified as typically GMO-derived
- Splenda (sucralose) and aspartame are called out as artificial sweeteners to avoid; Dr. Berg references a dedicated video on Splenda’s specific effects
Practical Identification Method
For sugar alcohols and other gut-irritating ingredients that may not be immediately obvious, Dr. Berg recommends a simple self-test: monitor your digestion. If a food causes gas or bloating after consumption, it’s a signal to eliminate that ingredient from your diet regardless of how it is labeled.