Intermittent fasting reduces many risk factors for diabetes, such as insulin resistance, obesity, high blood pressure, and fatty liver. Research shows that intermittent fasting can also lower blood pressure. Therefore, intermittent fasting seems to help prevent diabetes.
Diabetes is a devastating disease that increases the risk for many chronic conditions, such as heart disease, dementia, and cancer. 34.2 million people in the United States have diabetes. That’s about 1 in 10 people. Even more people are prediabetic: 88 million people, or about 1 in 3 people (1).
The rates are steadily increasing and are expected to rise dramatically in the coming years. Intermittent fasting is known to improve insulin resistance–the underlying cause of type 2 diabetes.
Does that mean that it can help to prevent diabetes?
Before we go into further details, let’s explain insulin resistance.
You probably know insulin as a blood sugar-lowering hormone that people with type 2 diabetes take to control their blood sugar.
Insulin resistance means that cells stop responding to insulin. The pancreas then has to produce more insulin to force sugar into the cells. Unfortunately, higher levels of insulin further promote insulin resistance–a vicious cycle (2).
Type 2 diabetes develops when the pancreas cannot supply sufficient insulin to control blood sugar. People can be insulin resistant for many years, or even decades, before being diagnosed with diabetes.
Intermittent fasting can break the cycle and reverse insulin resistance. It can thereby prevent diabetes and even improve already existing diabetes.
By improving insulin resistance, intermittent fasting also reduces many risk factors for diabetes:
High blood sugar is the primary symptom of diabetes. It can already be elevated in the prediabetic state.
Because insulin is a blood sugar-lowering hormone, blood sugar regulation gets worse with insulin resistance. High levels of insulin can somewhat compensate for the resistance to the hormone, but at an advanced stage of insulin resistance, blood sugar increases.
As intermittent fasting improves insulin resistance, cells remove sugar from the blood easier, and blood sugar returns to normal levels.
With intermittent fasting, fasting blood sugar levels, HbA1c (reflects long-term blood sugar levels), and blood sugar control throughout the day improve within a few weeks (3, 4).
Obesity is a strong risk factor for diabetes. In turn, losing weight decreases diabetes risk. But body weight is not the best indicator. Belly fat is the real problem. For this reason, a large waistline is a symptom of metabolic syndrome–a condition that is caused by insulin resistance and leads to diabetes.
Intermittent fasting makes it easy to lose weight. It regulates the appetite, and most people can lose weight without counting calories (5, 6, 7).
Why is intermittent fasting so powerful when it comes to weight loss?
The explanation is very simple. Insulin is not only a blood sugar-lowering hormone but also a fat-storage hormone. You can imagine that it is hard to lose weight (or better, fat) when a fat-storage hormone is strongly elevated. As insulin levels drop, you can easily access your fat storage, and hunger fades.
High blood pressure (hypertension) is another typical symptom of prediabetes and diabetes.
Insulin resistance is again the underlying cause.
High insulin levels promote salt retention in the kidneys. This leads to a higher salt concentration in the blood, and, as a consequence, the blood volume increases. The higher the blood volume, the higher the pressure within the blood vessels, and the blood pressure increases.
As insulin resistance improves and insulin levels go down, blood pressure also improves (8, 9).
With increasing insulin resistance, there is a high risk of developing fatty liver.
Luckily, fatty liver can be reversed–at least in the early stages–and intermittent fasting is, again, a powerful tool to achieve this (10). As soon as insulin resistance improves, fat in the liver gets broken down, and the organ can recover.
Fat in the liver interferes with the organ’s functions.
Because the liver has many functions regarding sugar levels and fat metabolism, too much fat in the liver results in elevated blood lipids and bad cholesterol.
For this reason, low HDL levels (the “good” cholesterol) and high triglycerides (blood lipids) are typical symptoms of metabolic syndrome. As liver health improves through intermittent fasting, HDL and triglycerides also return to their normal range (11, 12, 13).
It is well known that people with type 2 diabetes have a higher risk of heart disease and, thereby, a higher risk of heart attack and stroke. But heart disease can develop before diabetes is diagnosed.
The underlying insulin resistance is the driver of heart disease. By improving insulin resistance, intermittent fasting not only helps to prevent diabetes but also reduces risk factors for heart disease.
Again, this shows that intermittent fasting improves overall health and has a lot more to offer than facilitating weight loss. Weight loss is a side effect that follows as soon as hormones such as insulin fall back into balance.
Read more in our article : "Can intermittent fasting cure type 2 diabetes ?"
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1. A Snapshot: Diabetes In The United States. Centers for Disease Control and Prevention. 2021. https://www.cdc.gov/diabetes/library/socialmedia/infographics/diabetes.html
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3. Sutton EF, Beyl R, Early KS, Cefalu WT, Ravussin E, Peterson CM. Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metab. Jun 5 2018;27(6):1212-1221 e3. doi:10.1016/j.cmet.2018.04.010
4. Lowe DA, Wu N, Rohdin-Bibby L, et al. Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters in Women and Men With Overweight and Obesity: The TREAT Randomized Clinical Trial. JAMA Intern Med. Sep 28 2020;doi:10.1001/jamainternmed.2020.4153
5. Wilkinson MJ, Manoogian ENC, Zadourian A, et al. Ten-Hour Time-Restricted Eating Reduces Weight, Blood Pressure, and Atherogenic Lipids in Patients with Metabolic Syndrome. Cell Metab. Jan 7 2020;31(1):92-104 e5. doi:10.1016/j.cmet.2019.11.004
6. Anton SD, Lee SA, Donahoo WT, et al. The Effects of Time Restricted Feeding on Overweight, Older Adults: A Pilot Study. Nutrients. Jun 30 2019;11(7)doi:10.3390/nu11071500
7. Hutchison AT, Regmi P, Manoogian ENC, et al. Time-Restricted Feeding Improves Glucose Tolerance in Men at Risk for Type 2 Diabetes: A Randomized Crossover Trial. Obesity (Silver Spring). May 2019;27(5):724-732. doi:10.1002/oby.22449
8. Gabel K, Hoddy KK, Haggerty N, et al. Effects of 8-hour time restricted feeding on body weight and metabolic disease risk factors in obese adults: A pilot study. Nutr Healthy Aging. Jun 15 2018;4(4):345-353. doi:10.3233/NHA-170036
9. Harvie MN, Pegington M, Mattson MP, et al. The effects of intermittent or continuous energy restriction on weight loss and metabolic disease risk markers: a randomized trial in young overweight women. International Journal of Obesity. 2011;35(5):714-727. doi:10.1038/ijo.2010.171
10. Johari MI, Yusoff K, Haron J, et al. A Randomised Controlled Trial on the Effectiveness and Adherence of Modified Alternate-day Calorie Restriction in Improving Activity of Non-Alcoholic Fatty Liver Disease. Sci Rep. Aug 2 2019;9(1):11232. doi:10.1038/s41598-019-47763-8
11. Stote KS, Baer DJ, Spears K, et al. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. Am J Clin Nutr. Apr 2007;85(4):981-8. doi:10.1093/ajcn/85.4.981
12. Adlouni A, Ghalim N, Benslimane A, Lecerf JM, Saile R. Fasting during Ramadan induces a marked increase in high-density lipoprotein cholesterol and decrease in low-density lipoprotein cholesterol. Ann Nutr Metab. 1997;41(4):242-9. doi:10.1159/000177999
13. Aksungar FB, Eren A, Ure S, Teskin O, Ates G. Effects of intermittent fasting on serum lipid levels, coagulation status and plasma homocysteine levels. Ann Nutr Metab. Mar-Apr 2005;49(2):77-82. doi:10.1159/000084739
