Do Medications Break a Fast?
Intermittent fasting has become an increasingly popular approach to weight loss and health in recent years. The basic premise involves alternating between periods of fasting and eating. One of the most common questions that arises is whether taking medications during the fasting window will break the fast.
In this comprehensive guide, we'll explore how different types of medications may or may not impact fasting, which medications are considered "safe" to use during a fast, what the research says, and more.
How Fasting Works
First, let's briefly review how fasting works. During the fasting period, which may last anywhere from 12-72 hours depending on the chosen fasting protocol, only zero or very low calorie beverages such as water, coffee, and tea are consumed. The goal is to give the digestive system a rest while the body burns through glucose reserves and shifts into a metabolic state called ketosis. In ketosis, fat becomes the primary fuel source in the absence of carbohydrate intake from food.
When carbohydrate intake is severely restricted for an extended time, the body responds by breaking down glycogen stores in the liver and muscles. Glycogen is a form of glucose. Once glycogen levels start dropping, the body begins producing ketone bodies which serve as an alternative fuel source for the brain and other tissues.
In essence, intermittent fasting works by prolonging the fasting period long enough to deplete glycogen stores and trigger ketosis. Any calories or macronutrients consumed will stop or hinder this process. Therefore, many people wish to avoid medications that contain calories, carbohydrates, fats or anything that might stimulate an insulin response.
General Rules of Thumb
As a general rule, most supplements in pill, tablet or capsule form will not break a fast. Examples include:
- Multivitamins
- Minerals like magnesium, zinc, selenium
- Vitamin C
- Vitamin D
- Probiotics
- Fish oil or omega-3 supplements
- Medications like metformin and birth control pills
These supplements generally do not contain calories or macronutrients. If anything, they may slightly stimulate digestive processes. But the net caloric impact is negligible.
On the other hand, certain medications or supplements may contain hidden calories, carbs or ingredients that elicit an insulin response. These are more likely to be problematic during a fast.
Stimulating Insulin
One of the keys with intermittent fasting is keeping insulin levels low. Insulin is the hormone released by the pancreas in response to glucose in the bloodstream. When you eat carbs or protein, the rise in blood sugar triggers insulin secretion.
Insulin has two main roles. First, it enables cells throughout the body to take up and utilize glucose for energy. Second, it promotes glucose storage in muscles and liver glycogen. It also encourages fat storage by triggering lipogenesis (the formation of new fat) and inhibiting lipolysis (fat breakdown).
During a fast, the goal is to transition away from a glucose-dependent metabolism by depriving cells of dietary carbohydrates. Releasing insulin during the fasting window can hinder this metabolic shift.
Certain sweeteners like sucrose and high fructose corn syrup can stimulate insulin. Artificial sweeteners are controversial but may also elicit a small insulin response. For this reason, diabetics are often advised to avoid artificial sweeteners before blood tests that measure insulin.
Protein, especially the amino acid leucine, can also stimulate insulin secretion. While small amounts of pure protein generally won't affect ketosis, large doses of branched-chain amino acids may.
The takeaway is to avoid medications sweetened with sugar or artificial sweeteners, as well as high-protein supplements like protein powders or bars.
Common Medications & Supplements
Below is a summary covering how some common medications and supplements may or may not impact fasting:
Multivitamins
Most standard multivitamins, without additional herbs or sweeteners, will not break a fast. They provide essential micronutrients without calories or macronutrients.
Individual Vitamins & Minerals
Like multivitamins, single entity vitamin supplements like vitamin C, vitamin D, iron, calcium, zinc, and magnesium have no significant impact on fasting. Electrolytes like sodium, potassium and magnesium are especially important to prevent side effects when fasting.
Fish Oil & Omega-3s
Omega-3 fish oil supplements support heart health, brain function and immunity without breaking a fast. Some brands do contain vitamin E as an added nutrient, which is also fine.
Probiotics
Probiotic supplements help maintain healthy gut bacteria. They do not contain macros or calories and have not been shown to stimulate insulin. Some people note probiotics may cause mild digestive rumblings.
Medications for Diabetes
Metformin and other oral medications used to lower blood sugar in type 2 diabetics do not seem to interfere with fasting. However, diabetics should monitor blood sugar closely when fasting and adjust medications under medical supervision.
Birth Control Pills
Hormonal birth control pills should not sabotage fasting goals. The hormones are absorbed through the digestive tract without raising insulin.
Blood Pressure Medications
Medications for high blood pressure like lisinopril (an ACE inhibitor) do not contain macros or calories. But it's important to monitor BP when fasting, as values may change.
Thyroid Medications
Levothyroxine and other thyroid hormones are used to treat hypothyroidism. They may enhance metabolism but do not break a fast.
Seizure Medications
Anticonvulsant medications like lamotrigine are often prescribed in childhood epilepsy syndromes. There is no evidence they interfere with fasting. However, monitoring for side effects is important.
Antidepressants
SSRIs and SNRI antidepressants like fluoxetine and duloxetine have no calories and do not spike insulin. They should not break a fast.
Cough & Cold Medicines
Many over-the-counter cold medications contain sugars and other carbohydrate-containing ingredients. These could potentially break a fast, so check labels and opt for sugar-free versions when possible.
Pain Relievers
Non-steroidal anti-inflammatories like ibuprofen do not contain calories or carbohydrates. They will not break a fast. The same goes for acetaminophen.
Caffeinated Beverages
Coffee, tea and zero-calorie energy drinks are fine during fasting windows. While artificial sweeteners may elicit a negligible insulin response in some, most people can tolerate diet beverages without an issue.
Exogenous Ketones
Supplements like ketone salts and esters provide the body with beta-hydroxybutyrate (BHB), one of the main ketone bodies produced during fasting. Some argue BHB supplementation can prolong ketosis. But it may also inhibit endogenous ketone production.
MCT Oil or Powder
Medium chain triglycerides (MCTs) are a type of saturated fatty acid that is readily converted to ketones. MCT oil and powder can provide an energy source without affecting insulin. But it may reduce appetite which can make fasting easier.
Branched-Chain Amino Acids
BCAA supplements like leucine, isoleucine and valine promote muscle protein synthesis, but may also stimulate insulin at higher doses. Small amounts are likely fine but should be tested individually.
Intermittent Fasting Pills
Proprietary blends marketed specifically for use while fasting often contain herbs, amino acids, MCT oil and other ingredients that theoretically help maintain ketosis. But quality and safety evidence is lacking
FAQs
Do any medications or supplements break a fast?
Most supplements and medications do not contain calories or macros that will break your fast. However, some exceptions include medications containing artificial sweeteners, branched-chain amino acids, and proprietary blends specifically marketed for fasting.
Should I take medications and supplements while fasting?
It's generally fine to continue taking most medications and supplements during fasting periods. But you may consider taking them alongside food if they cause stomach discomfort when taken on an empty stomach.
What about multivitamins or fish oil supplements?
Basic multivitamins and fish oil supplements will not break your fast and can be beneficial while fasting to provide essential micronutrients.
Can I drink coffee or tea during my fasting window?
Yes, plain coffee, tea, and other zero-calorie beverages are perfectly fine to consume while fasting. Avoid adding cream, milk, or caloric sweeteners.
Should I take exogenous ketones while fasting?
The evidence on exogenous ketones is mixed. They may help prolong ketosis but may also blunt your body's endogenous ketone production. Use with caution.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.
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