Intermittent fasting is a powerful method to get high blood sugar under control. It lowers blood sugar even when intermittent fasting does not lead to weight loss. As a consequence, intermittent fasting also lowers insulin levels and improves insulin resistance.
Diabetes patients can lower their insulin dose, and research suggests that intermittent fasting helps prevent diabetes type 2.
Many people try intermittent fasting because they hear it’s a great strategy to lose some weight and because there are many health benefits associated with intermittent fasting.
But are you concerned what going so long without eating may do to your blood sugar levels?
That’s a great question and hopefully this article will explain what intermittent fasting can do to your blood sugar levels so you can make an informed decision about trying intermittent fasting!
There is always sugar in your blood and the amount of sugar can change based on the last time you eat and what was in that meal.
However, some people have chronically elevated blood sugar levels, or blood glucose levels, and that’s a problem. This is called hyperglycemia.
When your blood sugar levels are high, your pancreas releases a hormone called insulin. Insulin helps bring sugar into your cells to use for energy and any extra sugar will go to the liver to be stored or converted into adipose tissue (body fat) (1).
If your sugar levels remain elevated, so do your insulin levels. If this continues to happen, over time, your cells won’t respond to insulin the way they should (2, 3). To put this into perspective, think about when you change your clothes. When you first put on your shirt or pants, you feel it. But within a few minutes, you no longer notice it. This same thing can happen to your body with insulin…make sense? This is called insulin resistance.
Once your body no longer normally reacts to insulin, glucose doesn't enter the cells as easily and will build up in the blood, causing hyperglycemia
Most people know that hyperglycemia can eventually lead to type 2 diabetes. But did you know that high sugar levels can also increase one’s risk for other conditions like atherosclerosis, cancer, inflammation, and liver damage (4, 5, 6, 7, 8)?
Keeping your blood sugar levels under control is important to maintaining a healthy life and minimizing your risk for various diseases.
Studies have shown that intermittent fasting can help decrease your risk of type 2 diabetes because it helps your body regulate your blood sugar.
For example, a recent meta-analysis on twelve different studies showed that various forms of intermittent fasting helped decrease fasting blood glucose levels while helping to increase insulin sensitivity (9).
A 2018 case report was done in three people with type 2 diabetes and reported that after a month, all three people no longer required the use of insulin injections (10).
Another study compared the effects of modified alternate day fasting (eating about 25% energy needs on fasting days) and caloric restriction in patients with type 2 diabetes. The authors reported a greater decrease in insulin and insulin resistance in the fasting group. What makes this study really interesting is that the authors also reported a similar decrease in body weight in both groups, meaning it wasn’t just the weight loss that helped improve these patients’ insulin resistance, it was intermittent fasting (11).
Additionally, other studies have shown that some individuals who try intermittent fasting can decrease their blood sugar levels without losing weight. This is particularly interesting because these studies show that the decrease in blood sugar levels isn’t a result of the weight loss achieved through intermittent fasting but is instead a direct result of intermittent fasting alone (12, 13).
However, other studies have shown that intermittent fasting alone doesn’t help decrease blood sugar levels (14, 15). Don’t let this confuse you though! The participants who saw a significant decrease in their blood glucose levels had hyperglycemia and/or type 2 diabetes when they started the study.
This means that if you have high blood glucose levels, intermittent fasting can help you get control of your blood sugar levels. And if you don’t have hyperglycemia, this is actually good news because you don’t want your blood sugar levels to get too low. This means that intermittent fasting shouldn’t cause an unhealthy drop in your blood sugar levels…yay!
However, if you are prone to low blood sugar levels or are concerned about this for any reason, we encourage you to meet with your primary care physician before starting an intermittent fasting routine. You can also buy blood glucose monitors so that you can keep an eye on your sugar levels while at home.
Now that we’ve talked about how intermittent fasting influences blood sugar levels, you may be wondering how this happens. Well, there are a number of ways intermittent fasting helps maintain blood sugar levels:
There are certain compounds other than insulin that help glucose get into cells; they’re called GLUT receptors. Fasting increases their production, which means that glucose gets into your cells faster, meaning your blood glucose levels decrease (16, 17, 18).
Studies have shown that excess body fat also means extra fat in your liver. For insulin to work properly, there are body pathways that allow it to work. Having extra body fat can cause an increase of fat in your blood, which can prevent these pathways from working normally. This can cause insulin resistance while also causing your liver to release more glucose into your blood (19, 20).
Having high blood glucose levels puts you at risk for developing type 2 diabetes.
If you have hyperglycemia and don’t have type 2 diabetes yet, intermittent fasting may be a good strategy to use to get your blood sugar levels under control.
If you don’t have hyperglycemia, intermittent fasting shouldn’t cause your blood sugar levels to get too low.
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