Intermittent Fasting And When To Workout

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Intermittent Fasting And When To Workout

If you’ve decided to do fasting and have been looking into intermittent fasting and when to workout then you’re definitely going on the right track.

It’s well known that the best combination to keep in shape is a proper diet and regular exercise but the trick is, you need fuel (food) to perform your workouts efficiently.

So what does that leave you if you’re running on empty because of intermittent fasting? Will it be safe for your overall health? Read on to find out.

What Is Intermittent Fasting?

Intermittent fasting (IF) is when you alternate between eating and fasting intervals. An intermittent fasting diet isn’t about starving yourself; it’s about limiting your calorie intake for brief periods. 

Basically, you should eat all your meals during an 8-hour window every day, and the rest of the 16 hours are for fasting. Other times, your fasting hours can be longer depending on the type of fast you choose.

An advantage of intermittent fasting is there is no strict rule in what food you can consume during your eating window. But the concept is that you eat and  keep a healthy diet while experimenting what works for you.

Types Of Intermittent Fasting

It is critical to understand how to properly do intermittent fasting if you want to maintain sufficient nutrition in your overall diet while avoiding unnecessary risk.

If you do decide to practice intermittent fasting, you must first consider how to accommodate this eating pattern into your life, particularly regarding social engagements and staying active.

Know the different types of intermittent fasting below so you can best pick the one for you.

Time-Restricted Eating (16/8 or 14/10 Method)

You can specify your own fasting and eating windows under this option. 

This strategy is popular since you can schedule the majority of your fasting window when you’re fast asleep. It’s especially convenient because missing breakfast and not eating until lunch extends the overnight fast. This type of fasting is a safer option for you if you’re interested in trying intermittent fasting for the first time.

Some of the most common ways are: 

  • The 14/10 method – Eating window is ten hours and the fasting window is 14 hours.
  • The 16/8 method – Only eating for eight hours and then fasting for 16 hours.
  • This form of intermittent fasting can be repeated as often as you want or even once or twice a week, depending on your preferences.
Twice-A-Week Method (5:2 Method)

This method of intermittent fasting focuses on limiting your calories for two days each week. Then you eat a healthy and typical diet the other five days of the week.

This variation calls for a “modified” fast every other day. Limit your calories to 500 or around 25% of your regular intake on fasting days. There are also stringent variants to this technique, such as consuming zero calories on alternate days rather than 500.

This technique usually includes a 200-calorie meal (morning or lunch) and a 300-calorie dinner on fasting days. When fasting, it is recommended to focus on high-fiber and high-protein foods which is critical since it can help keep you full while keeping calories low.

The 24-Hour Fast (Eat-Stop-Eat Method)

Fasting for a total of 24 hours is done on this type of fast, as its name suggests. This is usually only done once or twice a week. 

You can fast from breakfast to breakfast or lunch to lunch. With this kind of intermittent fasting, the adverse effects should be considered, such as fatigue, headaches, irritability, hunger, and low energy.

On your non-fasting days, if you use this strategy, you should return to a healthy diet. Fasting for this many hours can be achievable but should only be done when you’ve already been accustomed to fasting such as the time restricted type of fast.

Benefits Of Intermittent Fasting

Weight Loss

Most people begin to notice losing weight when they continuously do intermittent fasting. This can be beneficial if you are overweight or obese. In one study, researchers examined data from 27 studies and discovered that IF helped patients shed up to 13% of their body weight1.

Reduced Blood Pressure

Intermittent fasting may help lower high blood pressure. A pilot study published in Nutrition and Healthy Aging in June 2018 discovered that the 16:8 fast significantly reduced systolic blood pressure in the 23 study participants2.

Reduced Inflammation

Although clinical research is few and far between, IF and general calorie restriction can lower inflammatory levels. A study done to a group of 50 people fasting during Ramadan was done and the results were that pro-inflammatory indicators, blood pressure, body weight, and body fat were all lower than usual during the fasting phase3.

Lower Cholesterol

High LDL (low-density lipoprotein) cholesterol can increase heart disease or stroke risk. Researchers discovered that IF lowered the presence of triglycerides, which are blood fats that might cause stroke, heart attack, or heart disease4.

Better Outcomes for Stroke Survivors

Lower cholesterol levels and lower blood pressure may significantly impact and lower your risk of stroke. However, that is not the only potential stroke-related benefit of IF.

Fasting may provide a protective mechanism for the brain and improve recovery following a stroke, according to a study published in Nutrients in October 2019. This conclusion however is based on animal studies; the researchers observed a shortage of human data on the effects of IF on stroke5.

Boosted Brain Function

IF may improve mental sharpness and attention. There’s preliminary evidence to back up that theory as a study published in Molecular Psychiatry in November 2021 discovered that fasting every other day may improve memory. However, this investigation was again conducted just on animals. 

A review published in Nutrients in September 2021 examined how IF impacted human brains and discovered that it does not appear to contribute to short-term cognition advantages in healthy people. Still, it may protect against the development of a neurological condition6.

Increased Cell Turnover

During your fasting period and at a certain fasted hours boosts autophagy, which is a key detoxification mechanism in your body to clean up damaged cells. This break from eating and digestion allows your body to repair and get rid of the garbage inside the cells that can speed up aging7.

Reduced Insulin Resistance

Intermittent fasting may help regulate blood sugar levels in diabetics as it resets insulin. According to the study, calorie restriction may reduce insulin resistance, which is a sign of type 2 diabetes. Fasting, such as the type associated with IF, causes insulin levels to decline, which may have a role in lowering the risk of type 2 diabetes8.

Intermittent Fasting And When To Workout

Numerous intermittent fasting types are available, so your specific workout schedule may determine when you eat meals versus when you work out.

However, most would prefer the morning as the best time to exercise primarily because you have a lot of energy after a full night’s rest. A few benefits to this is that you can cross off exercise early on since it’s in the first part of your day and less likely to have distractions.

Even so, as convenient as a morning workout would be, it might not be applicable for you. You will have to consider your unique situation to determine which workout strategy is best.

Things to Know About Intermittent Fasting and Work Out

Fasted workouts offer advantages. Exercising on an empty stomach may help you lose weight because your body will use stored fuel – glycogen and fat – instead of burning your most recent meal.

However, if you exercise in a fasting state, your body may begin to break down muscle mass for fuel. This is because high-intensity exercises rely on carbs for sustenance. Running sprints or doing your regular CrossFit or aerobic exercise while fasting or near the conclusion of your fast may reduce the advantages of your workout. If you’re new to IF, you can feel less motivated to work out hard.

While fasting high-intensity interval training may have detrimental effects, fasted low-intensity exercise – which operates mostly on fat – is fine before breaking your fast. Walking, running, yoga, cycling, and mild pilates are among the greatest intermittent fasting cardio workouts.

1. It is entirely up to you when you exercise.

When you work out, like when you eat, it should be determined by what makes you feel the best, the types of workouts you plan, and your fitness goals. Remember that while fasting, it’s better to adhere to low-intensity exercise and keep moderate to high-intensity activities for after you’ve broken your fast.

Activities that need power and speed also require fuel, so plan weight lifting and other high-intensity workouts around your meal times. This will improve your performance, and fueling your body before and after an intermittent fasting workout will aid muscle gain and recovery.

If you don’t have time to exercise during your feeding window, the time immediately following your fueling window is your next best alternative. Above all, if you don’t like how you feel, don’t do it! You may choose whichever you prefer and safe, be it working out on an empty stomach or working out after eating a little meal.

2. Refuel on protein after your workout.

Eat enough protein, high-fiber carbs, and healthy fats during your fueling windows to optimize your fast. Protein should be consumed within 30 minutes of completing any high-intensity exercise.

If you undertake low-intensity cardio on an empty stomach, do it after your fasting period so you can replenish immediately afterward. Consume whole, unprocessed foods that provide both protein and carbohydrates. You can have scrambled eggs with veggies, but a protein bar or protein shake is an excellent option on the run, and if you are looking for a quick and straightforward post-workout fueling alternative.

3. Hydration is everything.

Drinking plenty of water and electrolytes when fasting is critical, especially if you are also working out. If your electrolytes are not correctly balanced, you may experience headaches, dizziness, low blood sugar, low blood pressure, nausea, and cramping after a workout.

Electrolytes can be replenished with unsweetened coconut water, electrolyte tablets, or zero-calorie electrolyte drinks. Avoid sports beverages that are heavy in sugar, caffeine, or diuretics. Make sure you’re getting enough sodium and potassium and staying hydrated.

4. Don’t start intermittent fasting until you have adapted to a fat-burning (keto) metabolism.

If you want to mix keto and intermittent fasting, avoid starting both simultaneously. It takes a few weeks for your body to acclimate to any changes or new routines, so start with low carb before fasting to give your body time to adjust.

If you’re experiencing brain fog, weakness, dizziness, weariness, burnout, injuries, nausea, or are taking too long to recuperate from your workouts, it’s time to dial it down. Intermittent fasting and exercise can be challenging to balance. Also, extra activities make you feel hungry, making fasting much more complicated – especially if the intensity is too high.

5. Most importantly, listen to your body.

If you have specific medical issues (particularly ones that can cause dizziness, such as low blood pressure or low blood sugar), exercise while fasting may not be an option.

Pay attention to your body and do what feels right. Stop, refuel, and hydrate if you feel weak while working out. Consult your doctor or healthcare provider before beginning IF or adding exercise to your IF regimen and seek for advice on what’s best.

How Can You Safely Exercise While Fasting?

The success of any weight loss or exercise program is determined by how safe it is to maintain over time. Here’s a recap on the recommendations to help you achieve just that:

  • Eat a meal close to your moderate to high-intensity workout.

This is where meal preparation comes into play. Timing a meal close to a moderate to high-intensity activity is critical. As a result, your body will have some glycogen stores to draw upon to power your workout.

  • Stay hydrated.

Fasting does not imply dehydration. You need to consume extra water when fasting. Water also helps in keeping your hunger at bay.

  • Keep the intensity and duration fairly low.

Take a break and don’t push yourself too hard as you might feel dizzy or light-headed. It is critical to pay attention to your body.


Weight loss is one of the benefits of intermittent fasting and combining it with a workout takes the benefit to a whole new level. But before you start, you should be very careful in timing and choosing the type of workouts so that you can do them safely and productively.

To help you get through your fast, especially on your fasted workout, plan your meals accordingly to ensure that you are replenished with the right nutrients and aiding in the repair of your muscles and tissues.

Go slow and pay attention to your body. If you start to feel unwell, stop. If a fasted workout truly isn’t for you, you can always schedule your workouts during your eating windows. 


1 Welton S, Minty R, O’Driscoll T, Willms H, Poirier D, Madden S, Kelly L. Intermittent fasting and weight loss: Systematic review. Can Fam Physician. 2020 Feb;66(2):117-125. PMID: 32060194; PMCID: PMC7021351.

2 Faris MA, Kacimi S, Al-Kurd RA, Fararjeh MA, Bustanji YK, Mohammad MK, Salem ML. Intermittent fasting during Ramadan attenuates proinflammatory cytokines and immune cells in healthy subjects. Nutr Res. 2012 Dec;32(12):947-55. doi: 10.1016/j.nutres.2012.06.021. Epub 2012 Oct 4. PMID: 23244540.

3 Gabel, Kelsey et al. ‘Effects of 8-hour Time Restricted Feeding on Body Weight and Metabolic Disease Risk Factors in Obese Adults: A Pilot Study’. 1 Jan. 2018 : 345 – 353.

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5 Phillips MCL. Fasting as a Therapy in Neurological Disease. Nutrients. 2019 Oct 17;11(10):2501. doi: 10.3390/nu11102501. PMID: 31627405; PMCID: PMC6836141.

6 Dias GP, Murphy T, Stangl D, Ahmet S, Morisse B, Nix A, Aimone LJ, Aimone JB, Kuro-O M, Gage FH, Thuret S. Intermittent fasting enhances long-term memory consolidation, adult hippocampal neurogenesis, and expression of longevity gene Klotho. Mol Psychiatry. 2021 Nov;26(11):6365-6379. doi: 10.1038/s41380-021-01102-4. Epub 2021 May 25. PMID: 34031536; PMCID: PMC8760057.

7 Jamshed H, Beyl RA, Della Manna DL, Yang ES, Ravussin E, Peterson CM. Early Time-Restricted Feeding Improves 24-Hour Glucose Levels and Affects Markers of the Circadian Clock, Aging, and Autophagy in Humans. Nutrients. 2019 May 30;11(6):1234. doi: 10.3390/nu11061234. PMID: 31151228; PMCID: PMC6627766.

8 Grajower MM, Horne BD. Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus. Nutrients. 2019 Apr 18;11(4):873. doi: 10.3390/nu11040873. PMID: 31003482; PMCID: PMC6521152.


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