How to Fast for a Day


Many people fast for various reasons. Some fast for weight loss and health benefits, while others may fast for a day for medical or religious reasons. Regardless of why you’re fasting, it’s important to know how to fast and how fasting affects your body. Here is everything you need to start fasting.

How Should I Start My Fasting Day?

If you’ve never fasted before, you may wonder “How should I start my fast?” There are different ways that people choose to begin fasting. Some people fast for a few days, while others may fast for a few hours each day. Fasting can offer several benefits such as lowering weight and promoting longevity. However you choose to fast, here are some things to keep in mind. 

Start Slowly

If you’re new to fasting, start small and slow. Try fasting for short periods of time such as fasting for one meal. Some people eat dinner and then fast until dinner the next day. You can also eat breakfast and then fast until dinner. A popular choice for beginners is calorie restriction. For example, you can choose to eat only 500-600 calories during your fasting day. 

Drink Water

Regardless of your fasting method, it’s essential that you drink plenty of water. This will prevent dehydration. Your body draws extra water from the food you eat. When you’re fasting, you’re not getting as much water. Drinking extra water will help keep your mouth and body hydrated and prevent headaches. Try to drink at least 64 ounces a day.

Keep Moving

When you first begin fasting, you may feel tired. Light exercise, such as walking, can keep your body burning fat. Any light exercise is helpful for this process and gives you some energy. 

Is Fasting Good for One Day?

Many people choose to fast for one day rather than a few hours at a time. Fasting is good for one day because it’s a good way to cut back on calories and lower your cholesterol levels. Here are a few other reasons why fasting is good for one day. 

Fights Inflammation

There are foods that cause inflammation in the body. Refined sugars and processed foods contain preservatives that cause swelling and other health concerns. Studies show that inflammation can increase your risk of heart and autoimmune diseases. Fasting gives the body a chance to reduce inflammation that leads to these health issues. 

Improves Heart Health

Adding a fasting routine to your diet plan may improve your heart health. Heart disease is among the top health problems today. Fasting for a day can also help lower your risk of diabetes which can lead to heart disease. 

Boosts Metabolism

We already mentioned that fasting can aid in weight loss. Most people fast for this reason. But fasting is more than just restricting calories. Frequent fasting can train your body to enjoy good foods so you no longer crave processed ones. Over time, the metabolic function increases and lowers your weight at a healthy pace. 

Are There Drinks That I Can Have During a One Day Fast?

You should drink as much water as you can during a fast. Drinking water every day is important for a healthy body. When you’re fasting, you should drink more than you usually drink on a regular day. Fasting can dehydrate your body because you’re not getting water from food. Drinking water also helps keep hunger pain away. Try adding a little lemon or cucumber to your water for added benefits and taste. 

If you don’t have any dietary restrictions, you can also drink black teas, greens teas, or black coffee on a fasting day. Just make sure to skip the cream and sweeteners. A general rule of thumb is to avoid any drinks with higher calorie content as this may increase your insulin levels, breaking your fast.

What Are the Proper Steps to Fasting for the Day?

Now that we know why fasting is important, let's look at how to prepare for a fast. Preparing for a fasting day is just as important as the fast itself. 

  • Decide Your Method - Before you even begin, decide how you want to fast. Will you eat one light meal or nothing at all?
  • Skip the Sugar - Plan to reduce your sugar intake at least a week before fasting. Reducing your sugar and additives will make fasting easier.
  • Begin Slowly - Fast for short periods until your body gets used to fasting. If you plan on eating anything during the day, make your portion size smaller.
  • Exercise Gently - Vigorous exercise isn’t a good idea while you’re fasting. Choose light exercise like yoga or walking. 
  • Stay Alert - Pay attention to how you feel during a fast. If you’re not feeling well at all, stop your fast. Eat some healthy protein or a small healthy snack. Keep your doctor aware of how you’re feeling.

These are a few important steps for planning your fast day. Make sure to include your doctor in your plans. 

What Meal Should I Break My Fast With?

Although you may feel tempted to celebrate the end of fasting with a large meal, it’s not wise. Fasting lowers your blood sugar levels and boosts your metabolism. Once you start eating again, your blood sugar rises, and uses the food as fuel. So if you’re fasting for weight loss, break your fast with a meal of lean proteins and vegetables. Here are a few other meal choices when breaking your fast. 

  • Bone Broth - contains electrolytes and protein
  • Dark Greens - choices like spinach or kale are high in Vitamin B, C, and K. 
  • Fresh Fish - contains protein and Omega-3 fatty acids
  • Nuts - rich vitamins help balance out the body
  • Smoothies - add vegetables, fruits, coconut water for a whole food alternative

While these don’t seem like full meals, it’s best to go for small food choices after a fast. Try any of these options for a nutrient-rich meal.

Is it Recommended to Fast for One Day?

Not everyone chooses fasting for just one day. However, if the concept is new to you, it’s best to start with one day. Your muscles and liver store up glucose and send it out whenever your body needs it. If you fast for more than 8 hours, the liver empties out the glucose storehouses, telling your body it’s rest time. As long as you don’t have any health restrictions, fasting for one day is safe. 

If you have medical conditions, it’s important to talk with your doctor before you begin fasting. While some research shows fasting can help with weight loss or cardiovascular health, it’s not recommended for everyone. 

Spermidine and Fasting

One of the major underlying mechanisms of fasting is the autophagy process. Autophagy is your body’s natural cellular renewal process during which aged and damaged cells are cleared of built up toxic debris. This detoxification of your cells has several health benefits as it allows your cells to continue to operate unimpaired by damaging organelles. When fasting, our cells are deprived of nutrients. In need of other sources of energy our cells turn to unused or unwanted cellular material, converting them into fuel and ridding the cell of potentially harmful debris.

Spermidine is a fascinating molecule quickly becoming recognized in the health and wellness space. Spermidine has the ability to mimic fasting, inducing autophagy without the need to forego calories during the day. Spermidine plays a vital role in cellular health, aiding in cellular growth, metabolic functions, cellular homeostasis, and mitochondrial health. One of the major benefits of spermidine is the reduction of inflammation. This has a vast array of health benefits ranging from cognitive function to supporting immune health. Whether you choose to fast or not, spermidine supplementation is a great way to improve your health. Spermidine can be taken in conjunction with fasting to optimize the benefits of fasting.


  • Don Moxley - Director of Applied Science

    Don Moxley is the Director of Applied Science at Longevity Labs. Moxley draws upon his career as an athlete, a sports scientist, and an instructor to lead and educate on the science of autophagy and longevity.