If you’re one of the 37 million Americans who have diabetes or one of the 96 million Americans who have prediabetes, there are many dietary and lifestyle changes that can help you manage the condition and reduce complications.1 One popular dietary approach, intermittent fasting, is gaining a lot of attention, and for good reason.
Intermittent fasting may have potential benefits for weight loss, blood sugar control, and insulin resistance, which are all key in controlling type 1 and type 2 diabetes. There can be risk factors associated with fasting, however, so it’s important to talk to your healthcare provider prior to starting any fasting regimen, especially if you live with diabetes.
What is Intermittent Fasting? Is It Good for Diabetics?
Intermittent fasting (or IF) is a dietary pattern designed to incorporate brief periods of fasting into your routine. Unlike traditional fasting (often practiced for cultural or religious reasons), which can last days or weeks, intermittent fasting focuses on short-term fasts and offers more flexibility.
With IF, you’re focused on when you eat instead of what you eat. Many people prefer this type of plan because it allows them to reap the benefits without restricting their favorite foods. With other diets, the ketogenic (keto) diet, for example, people are constrained to a very small number of foods. This lack of variety can make long-term adherence to the diet difficult. If you enjoy a wide variety of foods and don’t mind limiting when you eat, IF may be a good option for you.
There are four main types of intermittent fasting that focus on the length of the fasting period and the length of the eating window: time-restricted eating (16/8), twice-a-week (5:2), a 24-hour fast, and alternate-day fasting. The most popular method is 16/8.
Does Intermittent Fasting Lower or Raise Blood Sugar?
Your blood sugar is determined by a number of factors, including diet, physical activity, and even stress. If you’re looking to optimize your blood sugar, it’s essential to make changes in all of these areas.
Focusing specifically on dietary patterns, fasting has been shown to significantly improve blood sugar. Not only can it lower your glucose levels during the window in which you’re abstaining from food, but it can also reduce your overall 24-hour blood glucose peaks. There is an added benefit if the eating window is kept to the morning and midafternoon (as opposed to the window being in the late afternoon and evening).2,3
Benefits of Intermittent Fasting with Diabetes
In addition to lowering your blood sugar, fasting can have positive effects on areas of your health as well. Here are the top health benefits associated with fasting:
- Improved insulin sensitivity
Research has shown that fasting lowers insulin and increases your body’s insulin sensitivity. This is true even when there is a minimal reduction in total calories.4
- Weight loss and management
Intermittent fasting can reduce waist circumference, abdominal fat, and overall body weight.2 Many systematic reviews and research have demonstrated that intermittent fasting is as effective as traditional calorie-restricted diets for weight loss.2,12
In 27 studies examined, weight loss occurred, ranging from 0.8 to 13 percent of initial body weight.13 Some research among people living with type 2 diabetes shows greater weight loss in intermittent fasting.14
Intermittent fasting restricts your calorie intake since eating windows are limited. This puts a person into a calorie deficit. Repeated calorie deficits turn into weight loss. Approximately 3,500 calories equals one pound. As a person reaches that calorie deficit, they will continue to lose weight.
- Reduced inflammation
Chronic inflammation plays a role in all major diseases, including diabetes, cancer, cardiovascular disease, and neurodegenerative diseases.5 Fasting decreases inflammation in the body, which reduces your risk of all of these conditions.6
- Lowered blood pressure
Fasting is associated with not only a reduction in blood pressure but also a reduced heart rate.7 Other diets like the DASH diet or Mediterranean diet help lower blood pressure based on the type of foods eaten. Pairing intermittent fasting with other well-researched diets could further lower blood pressure.
- Improved cholesterol and triglycerides
Research shows that intermittent fasting can reduce triglycerides, reduce LDL cholesterol, and raise HDL cholesterol, lowering your overall risk of heart disease.8
Main Risks of Intermittent Fasting with Diabetes
While there can be many positive effects from fasting, it doesn’t come without risks. Below are the negative effects of intermittent fasting to watch out for:
- Hypoglycemia (low blood sugar)
While aiming for balanced blood sugar with minimal spikes is important, you want to avoid your blood sugar dropping too low. This can cause you to feel tired, dizzy, or lightheaded.
- Hyperglycemia (high blood sugar)
While fasting generally lowers blood sugar, it can actually do the reverse in some patients with diabetes. Fasting hyperglycemia occurs when the liver produces excess glucose and is due to hormonal and metabolic dysfunction.9
The human body is made up of about 60% water, which is why it’s so important to stay hydrated.10 Food can be a good source of water, so you have to be mindful of dehydration during fasting windows.
- Electrolyte imbalances
Our sweat and urine contain more than just water, they also have electrolytes like sodium, potassium, phosphorus, and calcium. We typically replenish these minerals through our diets, so it may be a good idea to use electrolyte supplements during periods of fasting.
- Increased risk of nutrient deficiencies
A healthy diet provides your body with the vitamins and minerals it needs to function properly. Research has shown that fasting may cause deficiencies in B vitamins, as well as minerals like zinc and selenium.11
- Potential for unhealthy eating habits
Some people find it easy to practice intermittent fasting, but others find it very challenging. If you find yourself overeating or feeling out of control during your eating windows, fasting likely isn’t right for you. In order to get long-term results, you need to find a dietary pattern that works best for your lifestyle, preferences, and goals.
What to Do Before You Try Intermittent Fasting with Diabetes
If you’re interested in trying intermittent fasting, here are some helpful things to do before you start:
- Talk to your doctor: Both type 2 and type 1 diabetes are complex conditions, so all diet and lifestyle changes should be discussed with your healthcare team.
- Monitor blood sugar levels: In the long run, fasting can optimize blood sugar, but this sudden dietary change can cause swings initially. It’s important to closely track your blood sugar levels with Signos while you’re fasting.
- Adjust medication and insulin: Fasting can have many metabolic benefits, including increasing insulin sensitivity, so your body will require less insulin than it previously did. Work with your healthcare provider to modify medication and insulin levels or dosages if needed.
- Take it easy: Fasting is a major dietary shift for most people, so it’s a good idea to start slow. Begin by practicing shorter fasts, then build up over time. Check out Singos’ intermittent fasting diet guide for meal ideas.
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Topics discussed in this article:
- The facts, stats, and impacts of diabetes. (2023, April 4). Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/library/spotlights/diabetes-facts-stats.html
- Morales-Suarez-Varela, M., Collado Sánchez, E., Peraita-Costa, I., Llopis-Morales, A., & Soriano, J. M. (2021). Intermittent Fasting and the Possible Benefits in Obesity, Diabetes, and Multiple Sclerosis: A Systematic Review of Randomized Clinical Trials. Nutrients, 13(9), 3179. https://doi.org/10.3390/nu13093179
- Malinowski, B., Zalewska, K., Węsierska, A., Sokołowska, M. M., Socha, M. W., Liczner, G., Pawlak-Osińska, K., & Wiciński, M. (2019). Intermittent Fasting in Cardiovascular Disorders—An Overview. Nutrients, 11(3), 673. https://doi.org/10.3390/nu11030673
- Harney, D. J., Hutchison, A. T., Hatchwell, L., Humphrey, S. J., James, D. E., Hocking, S., Heilbronn, L. K., & Larance, M. (2019). Proteomic Analysis of Human Plasma during Intermittent Fasting. Journal of proteome research, 18(5), 2228–2240. https://doi.org/10.1021/acs.jproteome.9b00090
- Furman, D., Campisi, J., Verdin, E., Carrera-Bastos, P., Targ, S., Franceschi, C., Ferrucci, L., Gilroy, D. W., Fasano, A., Miller, G. W., Miller, A. H., Mantovani, A., Weyand, C. M., Barzilai, N., Goronzy, J. J., Rando, T. A., Effros, R. B., Lucia, A., Kleinstreuer, N., & Slavich, G. M. (2019). Chronic inflammation in the etiology of disease across the life span. Nature Medicine, 25(12), 1822–1832. https://doi.org/10.1038/s41591-019-0675-0
- Aly S. M. (2014). Role of intermittent fasting on improving health and reducing diseases. International journal of health sciences, 8(3), V–VI. https://doi.org/10.12816/0023985
- Gonzalez, J. E., & Cooke, W. H. (2022). Influence of an acute fast on ambulatory blood pressure and autonomic cardiovascular control. American journal of physiology. Regulatory, integrative and comparative physiology, 322(6), R542–R550. https://doi.org/10.1152/ajpregu.00283.2021
- Ahmed, N., Farooq, J., Siddiqi, H. S., Meo, S. A., Kulsoom, B., Laghari, A. H., Jamshed, H., & Pasha, F. (2021). Impact of Intermittent Fasting on Lipid Profile-A Quasi-Randomized Clinical Trial. Frontiers in nutrition, 7, 596787. https://doi.org/10.3389/fnut.2020.596787
- Sheehan J. P. (2004). Fasting hyperglycemia: etiology, diagnosis, and treatment. Diabetes technology & therapeutics, 6(4), 525–533. https://doi.org/10.1089/1520915041705910
- Dietary reference intakes for water, potassium, sodium, chloride, and sulfate. (2005). In National Academies Press eBooks. https://doi.org/10.17226/10925
- Jackson, J. M., Blaine, D., Powell-Tuck, J., Korbonits, M., Carey, A., & Elia, M. (2006). Macro- and micronutrient losses and nutritional status resulting from 44 days of total fasting in a non-obese man. Nutrition, 22(9), 889–897. https://doi.org/10.1016/j.nut.2006.06.001
- Rynders, C. A., Thomas, E. A., Zaman, A., Pan, Z., Catenacci, V. A., & Melanson, E. L. (2019). Effectiveness of Intermittent Fasting and Time-Restricted Feeding Compared to Continuous Energy Restriction for Weight Loss. Nutrients, 11(10), 2442. https://doi.org/10.3390/nu11102442
- Welton, S., Minty, R., O'Driscoll, T., Willms, H., Poirier, D., Madden, S., & Kelly, L. (2020). Intermittent fasting and weight loss: Systematic review. Canadian family physician Medecin de famille canadien, 66(2), 117–125.
Borgundvaag, E., Mak, J., & Kramer, C. K. (2021). Metabolic Impact of Intermittent Fasting in Patients With Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis of Interventional Studies. The Journal of clinical endocrinology and metabolism, 106(3), 902–911. https://doi.org/10.1210/clinem/dgaa926