How to Break a Fast Safely: Managing Blood Sugar Levels

Check out these tips and tricks for what foods to choose and which to avoid when finally breaking your fasting periods.

Sarah Zimmer, PT, DPT
— Signos
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Science-based and reviewed

June 12, 2024
December 18, 2023
— Updated:

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Intermittent fasting has gained immense popularity for its potential health benefits, weight management advantages, and simplicity as a dietary approach.1 

However, there is an art to both the abstention from food as well as the return to feasting - or breaking your fast. Breaking a fast is a delicate balancing act that can significantly impact your body's response and overall well-being. The transition requires a calculated approach, ensuring that your body reaps the rewards of fasting without encountering adverse effects.

Whether you follow the 16/8 method, the 5:2 approach, or any other intermittent fasting schedule, this article contains the tips, tricks, do’s, and don’ts of how to nourish your body with the right foods while offering insight into the nuanced art of breaking a fast safely.


Short Fasts vs. Long Fasts

The distinction between longer fasts and short fasts primarily lies in the duration of the “non-feeding” window. Short fasts span anywhere from eight hours to a full day, while long fasts extend beyond 24 hours, often ranging from several days to weeks. A popular example of a short, fast method is the 16/8 split in intermittent fasting. Conversely, long fasts, such as multi-day water fasts or extended fasts practiced for therapeutic purposes, involve more prolonged periods of abstaining from food.

Whether you choose a short or long fast method (or even a mixture of both), the first moment of reintroducing food isn't a one-size-fits-all meal plan. The emphasis relies on selecting nutrient-rich, wholesome foods to help replenish the body's stores effectively and maintain the benefits of fasting, which include lowered glucose levels and altered energy utilization. Regardless of breaking a short or long fast, opting for foods abundant in essential vitamins, minerals, electrolytes, healthy fats, and proteins ensures a smooth transition back to eating without ruining your hard-earned efforts.

Breaking Fasts Without Messing Your Glucose Levels

While fasting, the body shifts from relying on glucose to producing ketones for energy. Ketones are molecules produced by the liver when the body breaks down fat for energy in the absence of sufficient carbohydrates or glucose.3 They serve as an alternative fuel source for the body, especially during periods of fasting, low-carbohydrate diets, or intense exercise. Upon breaking the fast, the body quickly transitions back to utilizing glucose as its primary fuel source.2 

To avoid major disruptions or big spikes in your insulin levels, it's crucial to opt for nutritious meals that support a stable metabolism when breaking your fast. High-carbohydrate or sugary foods can cause rapid spikes in blood glucose, challenging the body's efforts to maintain balance after fasting. Instead, focusing on low-glycemic index foods, like leafy greens, non-starchy vegetables, lean proteins, and healthy fats, helps regulate glucose levels more gradually.4  

It's also important to avoid indulging in large, heavy meals as this can also trigger abrupt blood sugar peaks, potentially leading to discomfort and digestive distress. Instead, opting for smaller, balanced portions allows for a gentler reintroduction of nutrients without overwhelming the body's metabolic processes and minimizing the risk of digestive issues. 

How To Break a Short Fast Safely

When breaking a short fast (between 8 to 24 hours), prioritizing nutrient-dense, easily digestible meals is key. Opting for meals that blend protein, healthy fats, and fiber-rich carbohydrates can gently reintroduce nutrients without overwhelming the digestive tract. Consider meals like a hearty soup or a protein-rich salad with leafy greens, grilled chicken, avocado, and various colorful vegetables. These meals provide essential nutrients, support satiety, and offer a balanced combination of macronutrients to ease the body back into eating. The mixture of protein, healthy fats, and fiber is also perfect for sustaining healthy blood sugar levels. 

In addition to meal quality, paying attention to portion sizes and avoiding eating too quickly is equally crucial. Consuming smaller portions helps prevent overloading the digestive system, reducing the likelihood of GI discomfort after fasting. Eating slowly also allows the body time to adjust to the reintroduction of food, assists healthy digestion, and enables better recognition of fullness cues, promoting a more mindful and satisfying eating experience after the fasting period.

How To Break a Long Fast Properly

Similarly to a short fast window, safely breaking a long fast (more than 24 hours) also involves introducing small portions of easily digestible, nutrient-dense foods. However, contrary to a short fast, you may want to start with an even smaller portion at first again to prevent GI distress or major spikes in blood sugar. For example, consider starting with a bone broth-based soup, a small serving of steamed vegetables, or a piece of fruit like berries or a few apple slices. These options offer hydration, vitamins, and minerals while being gentle on the stomach, helping to kickstart digestion without causing a sudden spike in blood sugar levels.

The importance of consuming small amounts of food when breaking a long fast lies in improving the glycemic response. After an extended period without eating, the body becomes more sensitive to glucose, and consuming large quantities of food immediately can lead to rapid spikes in blood sugar levels. By opting for smaller portions, the body can gradually readjust to processing food, minimizing the risk of abrupt glucose fluctuations and allowing for a more stable glycemic response after a prolonged fasting period.11, 12

<p class="pro-tip"><strong>Also Read: </strong><a href="/blog/best-candy-for-low-blood-sugar">Best Candy for Low Blood Sugar (And Other Foods)</a>.</p>

7 Foods to Avoid When Breaking a Fast

While nourishing the body is essential, certain foods can disrupt the gentle transition from fasting to eating, potentially causing discomfort or compromising the fasting benefits. 

Here are several types of foods to be cautious of when breaking a fast, each with its potential to upset digestion, spike blood sugar levels, or hinder the body's adjustment to post-fast nourishment.

  1. Processed and Fried Foods: Items like fast food, chips, and heavily processed snacks can be hard to digest, potentially causing discomfort or bloating after a fast.
  2. Sugary Drinks and Meals: Drinks and meals high in sugar (i.e., fruit juice, candy, etc.) can cause a rapid spike in blood sugar levels, disrupting the body's metabolic balance after fasting. Remember, the goal of fasting is to improve blood sugar management over time. We want to keep our levels as stable as possible, whether fasting or eating.  
  3. Caffeinated Beverages and Alcohol: Alcoholic beverages can dehydrate the body and impact liver function, counteracting the benefits obtained during the fasting period. 
  4. Dairy Products: Dairy products might cause digestive distress in some people due to lactose intolerance or sensitivity, potentially leading to discomfort when breaking a fast. For your first meal after a fast, try minimizing dairy products to avoid GI distress (constipation, etc.). 
  5. Nuts/Seeds: Consuming excessive amounts of nuts or seeds after fasting can be heavy on the digestive system and potentially cause discomfort due to their high-fat content. These are great sources of healthy fats; however, moderation is key in the first meal after a fast.
  6. High-Glycemic Carbs: Foods like pasta, bread, or grains can lead to rapid spikes in blood sugar levels, disrupting the body's metabolic adjustment after fasting. These foods aren’t inherently bad; however, they might be best reserved for after you’ve had your first post-fasting meal. 
  7. Spicy Foods: Spicy foods can irritate the stomach lining, especially after a period of fasting, potentially causing digestive discomfort or heartburn.

Can Supplements Break Your Fast?

Many individuals take supplements during fasting periods to ensure they meet their vitamin and mineral requirements.5 However, it's important to note that while some supplements are considered safe to take while fasting, others can unintentionally disrupt the fasting state. 

Here is a list of supplements that are safe to consume while fasting and a few that may break your fast sooner than you planned. 

Supplements That Can Break a Fast

  1. BCAAs and Protein Powder: Protein shakes, including BCAAs (branched-chain amino acids), often contain added sugars, extra calories, and macronutrients that can trigger an insulin response and raise glucose levels.6,7 
  2. Fish Oil: Fish oil supplements may contain calories and fat, which could disrupt the fasting state, particularly in higher doses.
  3. Gummy Vitamins: Many gummy vitamins usually contain added sugars and calories, which affect the fasting state despite their vitamin content.

Supplements That Will Not Break a Fast

  1. Creatine: Creatine supplements, in their pure form without added sugars or calories, typically do not contain components that disrupt the fasting state.
  2. Multivitamins: Multivitamins that do not contain added sugars, fillers, or flavorings with calories are typically safe during fasting. It is important to find a high-quality product and read the label carefully.8
  3. Collagen: Pure collagen supplements generally do not contain added sugars or significant calories that break a fast. Again, be careful to read the ingredients, as many powder forms of collagen supplements are made with added sugars to enhance the flavor.9 
  4. Individual Micronutrients: Certain vitamins and minerals in their pure forms, like vitamin C, vitamin D, or magnesium, without added calories or sugars, are typically safe during fasting.
  5. Prebiotics and Probiotics: Both pre and probiotic supplements that do not contain added sugars typically do not impact the fasting state. Consuming either can help support gut health without providing significant calories.10
  6. ​​Fiber Supplements: Supplements like psyllium husk or soluble fiber without added sugars or calories are generally safe during fasting and can aid digestion without impacting the fast.

5 Tips to Break a Fast Without Risks

Breaking a fast is a delicate process that demands thoughtful consideration and planning to nourish the body effectively while avoiding digestive distress or abrupt changes in blood sugar levels. 

Here are several tips to facilitate a smooth and comfortable transition when breaking a fast, ensuring that you reintroduce food in a way that supports your body's needs. These strategies prioritize gentle nourishment, hydration, and mindful eating to optimize your post-fast experience and maintain the benefits gained during fasting.

  • Hydrate Yourself: Prioritize hydration with water, herbal teas, or infused water to rehydrate your body after fasting. Be careful to avoid any drinks with added sugars, as this can cause unnecessary spikes in your blood sugar. If you opt for coffee, aim for black coffee with healthy fats such as MCT oil, ghee, coconut oil, or butter. This coffee option is also something you can consume during your fasting period.
  • Resume Your Eating Schedule Slowly: Begin with smaller portions or lighter foods like bone broth or fresh fruits to ease your digestive system back into eating. This will reduce any GI distress that comes with eating larger portion sizes after a fast. 
  • Observe Your Body’s Response: Pay attention to how your body reacts to different foods and adjust your choices based on what feels best for your digestive system and overall well-being.
  • Eat Mindfully: Chew your food thoroughly and slowly to aid digestion, listen to your body's hunger cues, and avoid overeating.
  • Always Start Breaking Your Fast With a Liquid Meal Such as Broth or Smoothies: Staring with a liquid meal helps to increase your hydration while offering nutrient-dense nourishment during your first meal post-fast. Liquid meals can be easier to digest than solid foods, so this is a great option if you experience any digestive issues in the meal after your fast.  

Learn More About Healthy Nutrition with Signos’ Expert Advice

If you have more questions on improving your health, fitness, and nutrition, seek the expert advice of the Signos continuous glucose monitor and Signos team. A continuous glucose monitor (CGM) can give you the insights to make smarter nutrition and exercise choices. The Signos app provides a unique, personalized program to help you lose weight and reach your health goals. Take this quiz to see if Signos is a good fit for you and reach your goals faster than ever before.

<p class="pro-tip"><strong>Learn More: </strong><a href="/mediterranean-diet">Mediterranean Diet and Blood Sugar</a>.</p>

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Topics discussed in this article:


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About the author

Sarah is a Doctor of Physical Therapy, graduating from the University of Wisconsin Madison in 2017.

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