How to break your fast

Are you contemplating adding intermittent fasting to your low-carb, keto routine with the hope of intensifying your weight loss or speeding up your metabolic improvements?

Then you just might be wondering how best to break your fasts. What should you eat first? What gives the best results? What do you need to watch out for?

If you are new to fasting, or have had trouble in the past coming out of a fast, this guide can help you plan and execute the best ways to begin eating again after short or longer-term fasts.


1. Fasting: New twist on an old tradition

Historically, the word ‘breakfast’ described the first meal of the day — no matter when that meal occurred. It wasn’t until the 15th century that the word started being recognized as the meal you consume shortly after waking.

Nowadays, with intermittent fasting gaining popularity, the meaning of the word ‘breakfast’ is going back to its original roots. Breakfast for the intermittent faster is the meal consumed when you choose to break your fast, be it 6:00 AM or 6:00 PM.

Fasting, especially for religious purposes, has been a common occurrence for centuries. And generally, throughout most of human history, not much concern was given to how to break the fast.

However, in an age of poor dietary advice, when we are told to eat all day long — and when hyper-palatable highly processed food abounds — it can take a little more planning to resume eating in a way that achieves the most physical comfort and most effective results for your long-term health and weight loss goals.


2. The difference between short and long fasts

Every night when we stop eating and then go to bed, we go through a short-term fast until our first meal of the next day. Depending on when you ate dinner and when you consume your first meal after you wake up, you can easily go through a 12 to 16-hour fast — with no physiologic change to digestive functions.

Although there is no clear consensus or accepted definition about what the cut off is between a short and a long-term fast, most clinicians would say that anything between 12 to 24 hours is considered a short-term fast and usually does not require any special planning or treatment to break the fast.

Just remember, however, with short term fasts, it is a good idea not to binge on highly-processed, sugary, or high-carb foods because you will have basically undone the advantages of the previous 12 to 24-hours without food. Plan to eat a wholesome, low-carb, high-fat meal, such as any of the meals featured in the Diet Doctor recipes, and you will be just fine.


3. Ending a longer fast: a quiet gut revs up again

Longer-term fasts are different. While individual responses can vary, in our clinical experience anything longer than 36 hours for most people will likely reduce the number of digestive enzymes being produced by the pancreas and intestine. Resuming eating after a longer fast takes more planning and care.

As we start to incorporate fasting into our routines, our bodies physiologically take a bit of time to adjust to the new regimen, especially if we used to eat constantly. As chronic eaters, our bodies are constantly spending metabolic energy producing digestive enzymes to efficiently process the food we’re consuming. This changes when we first start fasting. The digestive enzymes are not needed or produced so metabolic energy can be directed to other body functions.

This may be one of the reasons people often report increased energy and feelings of wellbeing during a fast.1


4. Potential side effects of breaking a long-term fast

If you’ve been fasting long enough for your body to slow down its production of digestive enzymes, then you may experience some gastrointestinal distress when you start to eat again. This often comes in the form of:

  • Diarrhea or loose stools
  • Passing of undigested foods
  • Gas pains
  • Bloating
  • In very rare cases, nausea and vomiting
Since your body doesn’t have the digestive enzymes and juices available to breakdown the food you’ve consumed, the food sits in your stomach. It can take a few hours or more for your body to start to make what it needs to break it down. It’s during this period when you may start to experience unwanted stomach pains or diarrhea.

Apart from shortening the duration of your fast, two other factors can help minimize the occurrence of side effects:

  1. Fasting more regularly, and
  2. Planning the best food to eat to break the fast.
When you start fasting regularly, your body gets more used to the routine and does not stop the production of digestive enzymes. The result is a calmer gut when you resume eating.

In time, you should be able to end your fast any way you like, but you should exercise caution during specific times:

  • For the first two months after starting fasting.
  • Any time you increase the duration of your fast (e.g. going from a 16 hour a day regimen to a 36-hour intermittent regimen).
  • Fasting for longer durations when your last meal was a high-carb meal.
  • Fasting for a long duration following a holiday season or vacation, where you’ve been eating more frequently than usual.


5. Food choices for ending longer fasts

Until your body understands that you’re not in a state of stress but rather just eating less often, you might want to avoid eating foods that are tough on your system. Some people know that certain foods bother their digestive tract more than others. If you have problem foods, you should avoid them initially when you resume eating.

In general, we’ve found that these foods (and drinks) are the most problematic foods for people to consume when breaking their fast:

  • Nuts and nut butters
  • Seeds and seed butters
  • Raw cruciferous vegetables (cooked are fine)
  • Eggs
  • Dairy products
  • Alcohol
  • In very rare occasions, some people have difficulty digesting red meat or certain kinds of red meat.
Within six hours of ending your fast, you should be able to consume the foods on this list without difficulty.


6. The recommended protocol for breaking a fast

We’ve found in our Intensive Dietary Management Program the following protocol works best for those who experience distress while breaking their fasts:

Chicken salad with leaf vegetables and cherry tomatoes

  1. Drink a glass of water with psyllium husk and wait 15 to 30 minutes to eat. Add 1 tbsp of psyllium husk to 1 cup of water. Let it sit for 5 to 10 minutes before consumption. It will get very thick and jelly-like. This insoluble fibre helps the gut get working again.
  2. Start your meal off with a cup of tomato and cucumber salad with some chopped up parsley. You can add a tablespoon of extra virgin olive oil if you like.
  3. To play it safe, keep your protein sources to poultry or fish. They can be cooked in fat and poultry skin can be consumed. Try to limit your protein intake to the size and thickness of the palm of your hand.
  4. Fill the rest of your plate with non-starchy, above ground vegetables that have been cooked in healthy fats, like avocado or coconut oil, butter or ghee.
  5. Finish your meal off with an avocado if you’re still feeling hungry.

If you follow this protocol and still experience problems, try to take another tablespoon of psyllium husk in a cup of water. The next time you are fasting and are about to resume eating, you may want to try the above protocol but add in two tablespoons of psyllium in water at the start.



7. A word about alcohol

Avoiding alcohol, especially binge drinking, is very important when coming out of a fast of more than a day. Heavy consumption of alcohol could trigger alcoholic ketoacidosis, in which ketones are very high in the blood, but unlike diabetic ketoacidosis, blood glucose is usually dangerously low.2

The main symptoms are vomiting and abdominal pain.3 It is most common in people with alcohol addictions or strong dependence on alcohol who do not eat for a number of days and then drink heavily. However, it has been reported in individuals of all ages who have drunk heavily with little or no food intake.4



8. Understanding and avoiding refeeding syndrome

Refeeding syndrome is a very rare side effect of resuming food consumption after periods of malnutrition or extended times without eating. It’s defined as the “potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients.”5

The key clinical markers of this are very low blood phosphorus levels, or hypophosphatemia, as well as low blood serum levels of potassium, calcium and magnesium.6 These shifts can cause heart rhythm abnormalities, cardiac failure, respiratory problems, convulsions or coma.

Refeeding syndrome was first described among the severely malnourished North Americans who were held as Japanese prisoners of war during World War II.7 It has also been observed upon the treatment of long-standing anorexia nervosa and alcoholic patients in recovery.8

During the refeeding period, insulin and counter regulatory hormones such as cortisol and noradrenaline are suddenly re-activated. This causes the movement of the major intracellular ions like phosphorus, potassium, calcium and magnesium into our cells. However, due to the overall depletion of our body stores, this becomes quite excessive and leaves us with too little of these ions in the blood. This is what causes the major symptoms of refeeding syndrome:

  • Fatigue
  • Weakness
  • Confusion
  • Difficulty or inability to breath
  • Elevated blood pressure
  • Seizures
  • Heart arrhythmias
  • Heart failure
  • Coma
  • Death

These symptoms typically appear within two to four days of the start of refeeding.

Are you at risk of refeeding syndrome?

Currently, most of us are over-nourished rather than under-nourished. But that doesn’t mean you shouldn’t exercise caution. Certain groups of individuals are at a higher risk for developing refeeding syndrome than others:

  • Your body mass index (BMI) is less than 18.5.
  • You’ve experience unexplained weight loss in the last six months totalling a loss greater than 10% of your body weight.
  • You have fasted consuming nothing but water for five or more days.
  • Your blood work shows you have lower than normal levels of phosphorus, potassium, calcium or magnesium levels.
  • You are an alcoholic or have a history of alcoholism.
  • You have anorexia nervosa.
  • Are taking insulin, diuretics, antacids or undergoing chemotherapy.

How to avoid refeeding syndrome

There are several ways you can reduce your risk of developing refeeding issues when you to break your fast:

  • Avoid breaking your fast with a meal that is high in carbohydrates; stick to low-carb, high-fat meals. Avoid meals that surge insulin and blood sugar.
  • Avoid doing water-only fasts; instead drink 1 cup of bone broth every two or three days during your fast.
  • Stay hydrated during your fast; Drinking mineral water is good.
  • Supplement with a pinch of natural salt such as Himalayan salt a few times throughout the day.
  • Keep your fasts under 72 hours unless under medical supervision.


9. Summing it all up

When doing short fasts of 12 to 24 hours, you don’t need to worry too much about what you eat when you break your fast.

Stick to low-carb, high-fat meals — such as any of the recipes on the Diet Doctor site that seem appealing to you. Try not to eat too much. Fasting is never an excuse to gorge yourself when you resume eating.

For longer fasts, plan how you are going to end them. Resume eating with a small meal and eat slowly. Start with a nourishing bone broth or some psyllium husk in water. Eat a small fresh salad of tomato and cucumber and keep your protein on the light side, such as fish or chicken, and small — about the size of your palm or a deck of cards.

For more resources on intermittent fasting check out the other Diet Doctor guides and videos below.

/ Megan Ramos



The intermittent fasting video course