What is normal fasting blood sugar levels on intermittent fasting?

Normally, your fasting glucose level should be between 75 and 85 mg/dL. This is equivalent to one teaspoon of sugar in all of your blood.

Prediabetes level is 100-125 mg/dL, while diabetes is 126 or above. But when you’re doing keto and intermittent fasting and fully adapted to running on ketones and fat, your blood sugar will range between 50-70 mg/dL. If you look online you might get scared about having hypoglycemia (low blood sugar) which typically begins at a level of 70 and below, and labelled severe at 54.

You might think you need to start consuming carbs to bring your blood sugar back up. But don’t worry, this isn’t so. Your body is using ketones and fat and its need for sugar goes way down. The key is how you feel when your blood sugar is that low.

Are you feeling shaky, dizzy, or craving sweets? Are you thirsty? Or do you have lots of energy and feel great? If you feel great that means your body has adapted to ketones and this is your new normal.

But if you’re doing keto and intermittent fasting and your blood sugar is going up, there are a couple of reasons why. Your insulin will drop because your low carb diet stops spiking it. Chances are you have insulin resistance, which will take a while to heal. While it heals your cells still have too-low insulin, which allows your blood sugar to rise. If you’re concerned then you can exercise the extra blood sugar off.

What about fasting insulin? You can get a test called HOMA-IR to check your level. Your doctor may need to special order it because many of them aren’t aware of this test. It’s valuable because you’ll be able to see both your fasting blood glucose and fasting insulin levels to determine if you have insulin resistance.