What are normal blood sugar levels on intermittent fasting?

Typically, fasting blood sugar levels should be between 75 and 85 mg/dL. Levels between 100 and 125 mg/dL indicate prediabetes, while 126 mg/dL or above suggests diabetes. On a keto diet with intermittent fasting, your fasting blood sugar might drop to 50–70 mg/dL. While this can seem low, it’s normal if your body has adapted to using ketones for energy. The key is how you feel: if you’re energetic and well, this lower range is likely fine.

If you experience symptoms like shakiness or dizziness, it might be a concern. If your blood sugar rises on keto, it could be due to insulin resistance. Regular exercise can help, and a HOMA-IR test can check for insulin resistance by measuring both fasting glucose and insulin levels. Your doctor may need to special order this test.