Rules to Successfully Do Intermittent Fasting

Intermittent fasting is a popular dietary strategy. Read on to learn about intermittent fasting rules in order to do it successfully.
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Intermittent fasting is popular because of its ability to help with weight loss and for decreasing disease risk. But many people try this diet and don’t see any results and that’s because they aren’t doing it correctly. In this article, we discuss intermittent fasting rules to follow in order to see the results you want.

Written by
Christine Richardson, PhD
Clinical Project Manager at Becton Dickinson

When done correctly, intermittent fasting can be an extremely effective tool for weight loss and for improvements in overall health (1, 2). 

However, if done incorrectly, it can provide no results, which can be very discouraging. It can also cause prolonged fatigue, constant hunger, and even feelings of sadness. 

If you’ve suffered from this, it can be discouraging, and you may not want to continue on your intermittent fasting journey or maybe you’ve dismissed the idea altogether. Luckily, if you implement a few rules while intermittent fasting, you can use this diet to achieve your goals!

In this article, we provide you with some intermittent fasting rules that you should follow in order to do this diet correctly.

1. Don’t eat during your fasting window

Empty wooden plate and bowl.

Yes, this rule may seem a little obvious but it’s also an easy one to accidentally mess up. We all have so many daily habits that might contribute to us consuming calories outside of our fasting window without us realizing it.

For example, don’t add any sugar or cream to your coffee or tea in the morning. Even a little of either contains calories and will mess up your fasting day if you consume this outside of your eating window.

Think about your daily routine and make sure you aren’t accidentally consuming any calories outside of your eating window.

2. Be consistent with your eating window

This is an extremely important intermittent fasting rule to follow because you want to put your body on a routine. This is what helps you adjust to going longer without eating while also helping to align when you eat to fluctuations in normal bodily processes.

To elaborate, most of our bodily processes fluctuate throughout the day and, to a degree, we can change how they fluctuate (3). For example, if you consistently skip breakfast every day, your body will stop expecting food at that time and slow down processes related to digestion. You will also stop feeling hungry at that time…make sense?

This means that if you are not consistent with your eating window, your body will not adjust to you fasting.

3. Make sure you are eating enough food

Intermittent fasting should not be an extreme diet where you slash your calories in an attempt to lose weight fast. This is meant to be a long-term habit to help you regain control of your health and maintain it.

If you are in a caloric deficit for a long time, you can feel sluggish and irritable. To make matters even worse, you might plateau on your weight loss journey meaning all of that hard work will be for nothing!

You might be in a caloric deficit when you first try fasting and that’s ok because your body is adjusting. But after 2-3 weeks, you should aim to consume enough calories to properly fuel your body. Remember, food is fuel.

If you are curious about how many calories you need to eat each day, there are many calorie calculating websites that will give you an estimate based on your sex, height, weight, age, and activity level. You can always use a calorie tracking website or app as well to help you figure out exactly how many calories you are eating.

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4. Eat nutritious, wholesome food

Plate with salmon, different green vegetables and some rice.

The type of food you eat matters. Yes, you’ll see many websites touting intermittent fasting because you don’t need to watch what you eat and to some degree that is correct; however, intermittent fasting shouldn’t be used as a strategy to “get away with” eating poor quality food.

Your goal should be to be the healthiest version of yourself and the best way to accomplish that goal is by eating nutritious foods like fruits, vegetables, whole grains, lean meats, and healthy fats. 

Don’t get us wrong, there is a time and a place for everything…including sugar. If you are celebrating, eat that piece of cake…just make sure you find a good balance. If you can achieve this, you’ll look and feel great while not feeling deprived of your favorite foods.

5. Stay hydrated

Drinking enough water is incredibly important while intermittent fasting. This is because your body will use up its glycogen (stored sugar) for energy during your fast (4). When this happens, your body loses more water.

Therefore, you should aim to drink more water to avoid dehydration and the uncomfortable feelings that follow. 

This is especially true when you first start fasting because your body will be using more glycogen stores to use for energy as it adjusts to you not eating for longer periods of time. Make sure you pay attention to the color of your urine. If your urine is a bright or deep yellow, you should drink more water.

Now you may be wondering what to drink during your fasting window. Water along with black coffee or tea are great options (just don’t add anything with calories!). Drinking more might help you feel full too, which will come in handy while you are adjusting to fasting.

6. Don’t stop living your life

This is a very important rule-don’t let intermittent fasting rule your life. Intermittent fasting shouldn’t be something that stresses you out, causes you to not participate in major life occurrences, or causes you to have a negative mindset towards eating and food. 

Instead, this dietary strategy should be used as a tool to help make you feel healthier, more confident, and happier. Don’t let fasting come between you and some of the happy memories you can make in your life.

For example, if you try alternate day fasting and a different major holiday or celebration falls on a fasting day, make an exception and eat. 

You can choose to eat all day or choose to just be more lenient. If we use the same example from before, if a holiday falls on a fasting day for you, maybe try OMAD that day by only eating at your holiday dinner. The choice is up to you.

Just be careful to not make too many exceptions! You shouldn’t be making multiple exceptions every month and if you are, you might want to consider a different fasting window that better accommodates your schedule. 

What we’re trying to say is be strict but don’t let this diet make you miserable so make exceptions where appropriate. 

In Summary

Intermittent fasting can be a great tool to help you become a healthier version of yourself. However, in order to achieve your health goals, you must follow some intermittent fasting rules, otherwise, you may not see any success. These rules may seem difficult but you’re stronger than you think! And if you need group support, join our community of women doing intermittent fasting!

You may want to check these intermittent fasting tips and these common mistakes you should avoid doing.


1. Stockman MC, Thomas D, Burke J, Apovian CM. Intermittent Fasting: Is the Wait Worth the Weight? Current obesity reports. NIH Public Access; 2018. p. 172–85. 

2. Anton SD, Moehl K, Donahoo WT, Marosi K, Lee SA, Mainous AG, Leeuwenburgh C, Mattson MP. Flipping the Metabolic Switch: Understanding and Applying the Health Benefits of Fasting. Obesity. Blackwell Publishing Inc.; 2018. p. 254–68. 

3. Paoli A, Tinsley G, Bianco A, Moro T. The influence of meal frequency and timing on health in humans: The role of fasting. Nutrients. MDPI AG; 2019. 

4. Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: Illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition. American Journal of Clinical Nutrition [Internet]. Am J Clin Nutr; 1992 [cited 2021 May 30]. Available from:

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