It only takes about 12-hour for your body to start running out of glycogen and producing ketones for energy. So, what happens during the next 12-hour period? What are the benefits of a 24-hour fast?
Benefits of a 24-Hour Fast
Many of the benefits of a 24-hour fast start occurring sooner like weight loss and improved metabolic health. However, when you fast longer, you experience deeper ketosis and more autophagy. As you will see, one benefit you start experiencing at around 24 hours is intestinal cell renewal.
1. Weight Loss
Weight loss is often at the forefront of the mind of those who want to experiment with fasting. It’s no wonder. Fasting will increase your metabolism, regulate your appetite and improve your insulin sensitivity, which all contribute to weight loss. Fasting too long will slow down your metabolism, but intermittent fasting does tend to increase weight loss (up to 36 hours).
People lose more weight when intermittent fasting in part because they eat less. However, the weight loss can also be explained by the fact that fasting improves insulin sensitivity (we will talk about that in the next point). Insulin is a fat storing hormone.
How Much Weight Can You Lose With a 24-Hour Fast?
If you were to fast for 24-hours only twice a week, you could lose about 1-2lbs a week. A calorie deficit of around 3,500 calories is generally required to lose 1 pound a week. Most people consume about 2,000 calories a day. Skipping two full days of food would offer a calorie deficit of 4,000 calories. Plus, as we talked about, it would help you feel satisfied sooner on the days you do eat and possibly help your body store less fat.
2. Human Growth Hormone Secretion
Human Growth Hormone or HGH is a hormone that affects many aspects of your health. It’s involved in glucose metabolism, metabolic health and body composition, as well as muscle strength. Some people call it the fountain of youth because of its anti-aging benefits!
3. Improved Insulin Sensitivity
Improving your insulin sensitivity means that your body doesn’t need to produce as much insulin to transport glucose to your cells. Your blood glucose will remain more stable, which is especially helpful if you are at risk for diabetes.
Intermittent fasting is as effective as calorie restriction to improve insulin sensitivity.
As I mentioned already, insulin makes your body store fat, particularly around your middle. Improving insulin sensitivity improves your metabolic health. Besides weight loss and overall health, you may notice your energy level is more stable (bye bye afternoon crashes!).
4. Cardiovascular Health
As fatty acids become the main source of energy, your lipid profile improves. This will reduce your risk of heart disease and diabetes. Consequently, one of the benefits of a 24-hour fast is improving your heart health.
5. Reduced Inflammation
Inflammation has become a pretty trendy word in the natural health world. “Supplements to reduce inflammation”, “anti-inflammatory foods”, and “avoiding inflammatory foods” are phrases that we hear a lot. For good reason! Even though a certain level of inflammation is natural and helpful to fight common pathogens, chronic inflammation depresses your immune system and makes you feel tired and sick. It may also lead to autoimmune diseases as your body starts attacking itself. Chronic inflammation may even contribute to cancer!
Consuming refined carbs, refined oils, excessive alcohol, and processed foods all cause chronic inflammation. Moreover, insulin resistance contributes to inflammation. This may in part explain why after practicing intermittent fasting for one month, your inflammation biomarkers will decrease.
6. Improved Brain Function
Ketones are often referred to as “brain fuel.” In fact, the ketogenic diet was originally devised to help those who suffer from epilepsy. When you fast, or when your carb intake falls below 50 grams a day, your liver will increase ketone production to fuel your cells. Your metabolism will switch from using glucose to using ketones for energy. Many people notice that they experience greater mental clarity when the metabolic switchover occurs.
Furthermore, fasting protects your brain health by increasing the rate at which your brain cells regenerate. That’s not all! Since everything is interconnected in your body, the fact that fasting reduces inflammation also helps protect against neurodegenerative disorders like Parkinson’s and Alzheimer’s diseases. Not only that, but your body will start breaking down proteins linked to neurodegenerative disease when you fast for 24 hours.
I love to talk about how your body repairs itself when you fast. In my post What Is Autophagy and How to Induce It, I explain how fasting stimulates autophagy and improves longevity. In one study, rats that fasted every other day lived 83% longer than rats that didn’t fast. Of course, these types of results cannot be transferred to humans exactly, but it still demonstrates the healing power of fasting.
8. Intestinal Cell Regeneration
I mentioned already that the benefits of a 24-hour fast are not necessarily exclusive to fasting for 24 hours. However, intestinal cell regeneration starts happening at the 24-hour mark, so that’s one good reason to aim for 24 hours when you fast at least sometimes.
As you age, all the cells in your body don’t regenerate as fast. Intestinal cell renewal is particularly important for ensuring proper nutrient absorption and gut health.
When you fast for 24 hours, you start experiencing significant autophagy. Learn more in my post How Long Should You Fast For Maximum Benefits?
How Often to Do a 24-Hour Fast
Fasting once or twice a week is a good way to reap some of the benefits of a 24-hour fast.
Start fasting after dinner on say, Monday night. Eat dinner one hour later on Tuesday night to get your full 24-hour fast. Repeat on Thursday night. Sounds pretty doable, doesn’t it?
When I started experimenting with intermittent fasting after doing my first modified fast in the Fall of 2019, I started with one 24-hour fast a week. The results I was getting encouraged me to fast more frequently. However, when I started fasting every day, I reduced the length of my fasts to 20 hours. Do what works for you.
How to Break a 24-Hour Fast
When you fast for less than 24 hours, breaking your fast shouldn’t really concern you too much. Eat a good wholesome meal. If you struggle with digesting foods, stay away from those foods. It’s simple (What t.o Eat to Break a Fast (Don’t Sweat the Small Stuff))!
However, here are some tips you may find helpful:
- Make sure you drink plenty of water during your fast and drink a tall glass of water before breaking your fast. About one ounce of water per pound of body weight is usually recommended.
- Break your fast with foods that are nutrient-dense. Nutrient density is a way to assess the number of nutrients for the number of calories. Nutrient-dense foods have tons of vitamins and minerals and provide relatively few calories and tend to be easier to digest. The Power Shake is my favorite food to break a fast.
- Make your first meal light. It’s a good idea to break your 24-hour fast with a lighter meal and eat something heavier later.
- Choose foods that you tolerate well. The foods that you should consume to break a fast are the foods that usually make you feel good.
- Sit down and chew your food well. I am guilty of not always following my own advice and breaking my fast as I am preparing a salad, for example (I love these pieces of feta cheese and the huge garlic stuffed olives). However, it is best to sit down and enjoy your food slowly.
When it comes to the benefits of a 24-hour fast, it’s pretty simple: fasting benefits you, and the longer you fast, the greater the benefits (OK, up to a certain point!). Understanding this may make you wonder if you should attempt a 5-day water fast. Here’s my advice: before jumping into prolonged water fasting, try doing a few modified fast. The science behind modified fasting is very compelling and you may be able to reap all the benefits you ever want without having to go completely without food for a prolonged period.