Is Intermittent Fasting Good for Prediabetes?

If you’re experiencing symptoms of imbalanced blood sugar, including prediabetes, Type 2 diabetes, fatty liver or high cholesterol, intermittent fasting can be a valuable tool in your toolbox for reducing blood glucose, hemoglobin A1c, insulin and cholesterol levels.

Intermittent fasting is not a fad diet and it’s not about deprivation. Intermittent fasting is a structured way of eating that supports how the human body is designed to function.

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According to research published in the New England Journal of Medicine, “in humans, intermittent-fasting interventions ameliorate obesity, insulin resistance, dyslipidemia, hypertension, and inflammation.” (de Cabo, 2019).

When applied thoughtfully, intermittent fasting can be a powerful tool for restoring insulin sensitivity, improving metabolic health, and creating more stable energy, mood, and appetite.

What Intermittent Fasting Is and Is Not

Intermittent fasting is not a specific food plan and is not the same as caloric restriction in which daily calories are reduced by 20–40%, but meal frequency remains the same (AKA the typical “calorie-counting diet”).

Intermittent Fasting is a timing strategy in which you choose periods of eating and periods of not eating. During the non-eating period (the “fasting window”), calories are avoided. Water, plain tea, mineral water, and black coffee are usually allowed.

Common approaches to intermittent fasting include:

• Daily time-restricted eating

• 12 hours eating, 12 hours fasting, or

• 14 hours fasting, 10 hours eating, or

• 16 hours fasting, 8 hours eating

• Alternate-day fasting

• 5:2 intermittent fasting (fasting 2 days per week)

Fasts longer than 16 hours can also be therapeutic in some cases, but for people with prediabetes or type 2 diabetes, consistency matters far more than extreme fasting.

Why Intermittent Fasting Supports Metabolic Health

Metabolic health is largely about how efficiently your body handles fuel. In prediabetes and Type 2 diabetes, insulin is often high, but cells don’t respond well to it. Blood sugar remains elevated, fat storage increases, and energy becomes unstable.

Intermittent fasting helps by changing the pattern of glucose and insulin exposure.

Lowering insulin and restoring sensitivity

One of the biggest challenges to modern metabolic health is constant grazing.

Every time you eat, especially sugar-sweetened drinks or starchy or refined carbohydrates, your blood sugar rises. The hormone insulin also rises because insulin’s job is to get glucose out of the bloodstream.

Frequently snacking, mindlessly popping bits of food or a piece of candy in your mouth, or drinking sweetened drinks throughout the day and evening (what I call “grazing”), keeps insulin elevated almost continuously. This is not how human physiology evolved. Historically, humans ate meals and then went for hours without food, while also moving their bodies throughout the day. This pattern allowed insulin to fall, fat to be used for fuel, and cellular repair to occur.

When insulin stays high all day due to frequent eating, compounded by a sedentary lifestyle, the result is insulin resistance. Over time, insulin resistance leads to prediabetes, Type 2 diabetes, weight gain, inflammation, fatigue, and hormonal imbalance.

Fasting windows allow insulin levels to fall, which is essential for restoring insulin sensitivity.

Encouraging fat burning and metabolic flexibility

Insulin clears glucose from the bloodstream by facilitating the uptake of glucose into cells. Insulin puts excess glucose into storage as glycogen in your muscles, liver, and fat. The glycogen in muscles is easy to access – it gets used up during exercise. Glycogen in the liver and fat cells is harder to access because insulin is a fat storage hormone and as long as your insulin level is high, your body cannot burn stored fat for energy.

Restricting calories during a fasting period reduces insulin levels and allows the body to tap into stored energy. Once circulating glucose and insulin are reduced, the body shifts toward breaking down stored body fat for fuel.

This process supports fat loss, especially visceral fat around the organs and in the liver, reduces swelling and inflammation, and improves metabolic efficiency. For many people, adopting intermittent fasting leads to significant improvements in blood sugar and cholesterol levels, and body composition.

Supporting hormones, energy, and brain function

When blood sugar stabilizes and insulin demand decreases, people often notice secondary benefits including improved energy levels, better sleep, clearer thinking, and more stable mood. Hunger hormones also become more regulated, making eating feel calmer and more intuitive.

Why This Matters for Prediabetes and Type 2 Diabetes

Prediabetes is a signal that insulin resistance is developing or has already developed. Type 2 diabetes represents a more advanced stage of the same dysfunction. Reversal of these conditions requires reversing insulin resistance and improving how the body processes fuel.

By lowering insulin exposure and giving the body time to use stored energy, intermittent fasting supports improvements in:

• Fasting and post meal glucose levels

• Insulin levels and insulin sensitivity

• Triglyceride levels and fatty liver

• Weight and waist circumference

• Energy, cravings, and mental clarity

Dr. Jason Fung is even more blunt about the effects of intermittent fasting on type 2 diabetes. According to Fung, “Fasting, the voluntary abstinence from food, has been know to cure diabetes for close to 100 years” (Fung, 2018).

The Minimum Effective Dose of Fasting

For most people, a 12-hour overnight fast between dinner and the first meal of the day is the bare minimum needed to support metabolic health. If you’re sleeping the recommended 7-9 hours per night, most of the 12-hour fast happens while you sleep. A 12-hour overnight fast alone often reduces nighttime snacking and improves morning blood sugar.

For those with metabolic dysfunction, extending the fasting window to 14 or 16 hours per day can be a highly effective part of an overall strategy to restore insulin sensitivity.

Longer fasts are not automatically better, and they should feel sustainable rather than punishing.

How to Get Started Without Feeling Starved

When done well, intermittent fasting supports insulin sensitivity, energy, mood, and long-term metabolic health. When done poorly, fasting can worsen blood sugar swings, disrupt menstrual cycles, increase cravings, and contribute to fatigue or burnout.

The trick is to figure out how to intermittently fast in a way that does not feel like intermittent starving. Here are a few strategies:

1.     Start slowly.

2.     Prioritize high quality fats during the eating window. Adequate fat intake helps slow digestion, reduce blood sugar spikes, and keep energy steady between meals.

Helpful fat sources include avocado, olive oil, grass fed butter or ghee, nuts, seeds, and fatty fish. These foods support insulin sensitivity and make fasting feel calmer and more sustainable.

3.     Ensure your last meal before a fast contains sufficient fat and protein. Break your fast with a meal that includes healthy fats and protein rather than only carbohydrates. This can significantly reduce blood sugar crashes and excessive hunger later.

4.     Once you are consistently fasting for 12 hours overnight, begin by extending your overnight fast. Finish dinner earlier and gradually push breakfast back by 30 to 60 minutes at a time. Stay there until your energy feels steady.

Many people naturally move from three meals per day to two meals per day as insulin sensitivity improves. If you feel shaky, anxious, dizzy, or overly hungry, it’s a sign to slow down and focus on meal quality rather than fasting length. This should feel like a natural reduction in hunger, not forced restriction.

5.     Use supportive tools that keep you motivated

Intermittent fasting is ultimately about consistency. For many people, simple support tools can make fasting feel more approachable and sustainable.

Fasting tracking apps can be surprisingly helpful, especially in the early stages. Their main value is not perfection or data overload, but awareness. Unlike general diet tracking apps that focus on calories consumed or macronutrient ratios, fasting apps center around when you eat and include features such as:

·       Dedicated fasting timers

·       Structured plans & guidance

·       Motivational features such as fasting streaks

·       Insights into whether you are in carb-burning mode or fat-burning mode

A fasting app can help you:

·       Track fasting and eating windows without mental math

·       Build consistency with overnight fasts

·       Notice patterns between fasting length, energy, sleep, and hunger

·       Reduce decision fatigue around when to eat

For many people, simply seeing a visual timer motivates them to stay the course until they’ve achieved their goal time. Apps can also reinforce the idea that hunger comes in waves and does not always require immediate action. This can be particularly helpful for those transitioning from frequent snacking to structured meals.

There are many fasting apps you can try, a few popular ones include:

·       Fast habit – a free app that essentially acts as a timer. Additional features available with a paid subscription.

 ·       Zero – a robust app that requires a subscription. Allows users to track different fasting windows and offers guidance on setting up a fasting schedule to support your stated goals. Also offer hydration tracking and syncs to an Apple Watch.

 ·       Simple -- combines fasting tracking with gentle lifestyle guidance. It focuses on habit building rather than strict rules and includes education around blood sugar stability, hunger cues, and meal timing.

 ·       Feel Great App – this app supports habit formation while using Unicity’s Feel Great System. The Feel Great System combines yerba mate and a fiber supplement to support intermittent fasting and reduce blood sugar levels after a meal. The app shows you whether you are in a carb-burning mode, fat-burning mode or a hybrid stage in your fast.

Fasting apps are tools, not requirements. The best app is the one that supports calm consistency rather than obsession. Their purpose is to increase awareness, reduce mental load, and help build consistency. If tracking increases stress, it’s a good idea to step away and rely on internal cues instead. Once fasting feels intuitive and blood sugar is stable, many people naturally stop using apps altogether.

6.     Use supportive tools that help manage hunger and energy

One reason fasting feels difficult is not willpower—it’s physiology. Hunger, low energy, and cravings are often signs that insulin and appetite hormones aren’t being well supported yet.

A supportive tool for managing hunger and energy levels in the context of fasting is yerba mate – an herbal tea made from the dried leaves of Ilex paraguariensis, a plant native to South America. Yerba mate has been consumed for centuries, particularly in Argentina, Uruguay, Paraguay, and southern Brazil.

I first learned about yerba mate from Dr. Ben Bikman, Director of the Diabetes Research Lab at Bringham Young University, who supports using yerba mate to support metabolic health (Bikman, 2025).

Unlike typical teas or coffee, yerba mate contains a unique combination of naturally occurring caffeine, antioxidants and anti-inflammatory compounds. This blend is known for providing steady energy, mental clarity, and appetite support without the sharp spikes and crashes often associated with coffee. Historically, it has been used to support endurance, focus, and satiety which make it particularly relevant in the context of intermittent fasting and metabolic health.

Used appropriately, yerba mate may help reduce hunger during the fasting window, support steady energy, and make it easier to extend time between meals without breaking a fast or relying on stimulants that lead to crashes.

What to Eat During the Eating Window

Unfortunately, the Standard American Diet (SAD) is heavy in sweet drinks, refined carbohydrates and ultra-processed foods. Intermittent fasting is not a panacea that will improve metabolic health despite continuing to eat the SAD.

Intermittent fasting works best when meals are nutrient-dense and balanced.

Focus on:

• Protein at every meal

• Fiber from non-starchy vegetables

• Healthy fats like olive oil, avocado, nuts, and seeds

• Adequate hydration and minerals

If the goal of intermittent fasting is to restore insulin sensitivity, then whole grains and starchy whole food carbohydrates, such as potatoes or winter squashes, need to be carefully monitored in the diet. These foods typically cause an exaggerated blood glucose response followed by a sharp increase in insulin. Using a continuous glucose monitor can be a helpful tool for identifying your tolerance to grains and starchy carbohydrates.

For Women, Fasting Needs a Different Approach

One of the biggest gaps in most fasting advice is the assumption that what works for men will automatically work for women. The reality is that female physiology is more hormonally complex then male physiology. That complexity calls for a fasting strategy that works with hormones rather than against them (Pelz, 2022).

Fasting Should Match Hormonal Rhythms

Female hormones shift throughout the month, and fasting tolerance shifts with them.

For women who have a menstrual cycle, the first half of the cycle is generally more supportive of fasting. During this phase, estrogen is rising and the body is more metabolically flexible. Many women find they can tolerate slightly longer fasting windows during this time without negative effects.

In the second half of the cycle, progesterone increases and the body becomes more sensitive to stress. During this phase, longer or more aggressive fasts are more likely to backfire. Appetite often increases as the body signals a need for more calories, more carbohydrates, and more rest. Honoring this phase often leads to better long-term results than pushing through it.

Cycling women tend to do best with a flexible approach that alternates between eating and fasting in a way that feels supportive. This might look like several days per week with a 14 hour fast, combined with days where meals are eaten earlier and more frequently. A flexible fasting routine supports insulin sensitivity without sending a signal of chronic scarcity that triggers stress hormones.

For women in perimenopause, hormonal patterns are less predictable, which makes rigidity less helpful. Consistent long fasts can sometimes increase stress hormones. A better approach is variation. Some days may include a longer fasting window, while other days emphasize regular meals and nourishment to support the nervous system and hormone production.

Postmenopausal women have more stable, albeit lower, hormone levels than earlier in life. Postmenopausal women can typically do 12-16 hour fasts on most days, and longer fasts occasionally.

For more information on fasting for women, I highly recommend Dr. Mindy Pelz’s book: Fast Like a Girl.

Who Should Be Cautious and When You Should Stop

If fasting ever feels like constant willpower, white knuckling hunger, or ignoring symptoms, it’s no longer serving its purpose. In this case, dial back your fasting efforts and focus on other fundamentals that may need support, such as eating a nutrient-dense whole foods diet and preventing hypoglycemic events in which blood sugar levels drop too low, before attempting fasting again or extending a fasting window.

Caution with intermittent fasting is also essential for anyone on medication or insulin to lower their blood-sugar level or blood pressure. Intermittent fasting naturally lowers these levels, therefore medications may need rapid reductions when fasting is introduced. Anyone using these types of medications should discuss fasting with a healthcare provider before beginning and know how to access their provider to receive timely instructions on adjusting dosages. Reducing meds is a positive and desired consequence of fasting, but it must be done safely!

Intermittent fasting is also not a good idea for the following groups of people:

• Adolescents or children

• Pregnant or breastfeeding women

• Have a history of eating disorders

• Underweight, frail, or recovering from illness

• Experiencing chronic stress or severe fatigue

Intermittent Fasting Is a Tool, Not the Whole Plan

The most reliable improvements in metabolic health come from combining habits:

• Structured meal timing

• Protein and fiber at meals

• Reduced ultra processed foods

• Reduced snacking

• Strength training and daily movement

• Adequate sleep and stress regulation

Intermittent fasting fits into this plan because our bodies were not designed to graze from morning until night. They were designed for cycles of eating and fasting. Intermittent fasting reduces constant insulin exposure, supports fat burning, improves hormone balance, and helps many people feel calmer and more in control around food.

For people with prediabetes or Type 2 diabetes, intermittent fasting can be a practical and effective way to restore insulin sensitivity and improve metabolic health -- as long as it is done thoughtfully. Start with an overnight fast, extend gradually, prioritize nourishing meals, and pay attention to how your body responds. When fasting feels supportive rather than stressful, it becomes a sustainable tool for long term metabolic resilience.

If you’d like to improve your metabolic health using intermittent fasting, schedule a free call. We’ll discuss your goals and how I can help you achieve them.

REFERENCES

Bikman, B. (2025, August 11). Yerba Mate and Metabolism - What the Science Says with Dr. Ben Bikman [Video]. YouTube. https://www.youtube.com/watch?v=DtJ9tYfYxI0

de Cabo, R., & Mattson, M. P. (2019). Effects of Intermittent Fasting on Health, Aging, and Disease. The New England Journal of Medicine, 381(26), 2541–2551. https://doi.org/10.1056/NEJMra1905136

Fung, J. (2018). The Diabetes Code. Greystone Books Ltd.

Pelz, M. (2022). Fast Like a Girl. Hay House, LLC.

Disclaimer

The information provided is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Do not use the information provided herein to diagnose or treat a health problem or disease. If you have or suspect that you have a medical problem, contact your physician promptly. Any Information or statements regarding dietary supplements have not been evaluated by the Food and Drug Administration and are not intended to diagnose, treat, cure, or prevent any disease.

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