12 Hour vs 16 Hour Fast

If you’re wondering whether a 12-hour fast or a 16-hour fast is better for you to achieve your health goals, you’re at the right place.

This post will share the differences between the two and let you decide based on your lifestyle and needs.

First, you should consult a licensed medical physician before jumping into intermittent fasting. IF isn’t for everyone; therefore, it’s something to discuss with a licensed professional. 

The purpose of this post is to give you a simplified version of the differences between 12 hours and 16 hours of fasting; it is not to provide any professional/medical advice.

Jump to:

• Is It Better to Fast for 12 or 16 Hours?
• Is 12 Hour Intermittent Fasting Enough?
• Benefits of 12 hour Fasting
• Benefits of 16 Hour Fasting
• Benefits Comparison Chart
• How Often Can You do 12 Hour Fasting vs 16 Hour Fasting?
• What Happens When You Don’t Eat for 12 Hours?
• What Happens When You Fast for 16 Hours
• Choose The Best Intermittent Fasting Schedule for You

Is It Better to Fast for 12 or 16 Hours?

The easiest way to get started with intermittent fasting is by doing a 12-hour fast and increasing your fasting time to 16 hours as you get used to it.

There are 12 hour intermittent fasting benefits you can feel in just a few days, such as more mental clarity and focus, cellular repair, and jumpstarting your weight loss journey.

While studies show that a minimum of a 12-hour fast is enough to help you get the benefits, the 16/8 intermittent fasting method is by far the most popular out there.

If your goal is weight loss, both a 12 hour and a 16 hour fast are beneficial. If your goal is to heal damaged cells, and cellular repair, you’ll need to fast for 14 to 16 hours to enter this stage of intermittent fasting.

Is 12 Hour Intermittent Fasting Enough?

This is the million-dollar question among beginners and long-term intermittent fasting practitioners.  

While research shows that 12 hours is enough, those who practice intermittent fasting and follow a keto diet swear by the 16-hour fasting window to help them stay in ketosis.

That said, many people do intermittent fasting without keto to achieve their health goals.

Benefits of 12 hour Fasting

The benefits of 12 hour fasting include weight loss, improved digestion, improved sleep, increased mental health and clarity, and reduced insulin resistance. 

One reason the 12-hour fast is great to start intermittent fasting is that most people spend 7 to 8 of those hours sleeping, and therefore, getting to 12 hours without eating requires little effort or struggle.

Benefits of 16 Hour Fasting

The benefits of a 16-hour fasting schedule are the same as a 12-hour fasting. They include weight loss, aid in the cellular repair process, improved sleep, improved digestion, increased mental health and clarity, and reduced insulin resistance.

The main difference is that after 14 to 16 hours, your body can enter the autophagy phase, where it begins to repair itself at a cellular level.

If you’re following a keto diet while fasting, the 16 hour fast tends to help many people stay in ketosis by providing the body an extra 4 hours to not produce any insulin from the foods consumed when breaking the fast.

How Often Can You do 12 Hour Fasting vs 16 Hour Fasting?

Most people practice intermittent fasting regularly. It is also possible to alternate between fasting 12 hours on some days and 16 hours on other days; it just depends on your lifestyle and schedule.

There’s no rule on how often one should fast and not fast, that said, pregnant or nursing women should not practice intermittent fasting.

What Happens When You Don’t Eat for 12 Hours?

With a 12-hour fast, when you omit to eat, your body can focus on other processes other than digestion.

This means that your body can begin to reduce inflammation, convert its fat stores into energy, get a more restful sleep, release ketones into the bloodstream, wake up more alert and have more focused energy in the morning, and more.

What Happens When You Fast for 16 Hours

A 16 hour fast is considered the standard for people who practice intermittent fasting long-term.

A lot of people express that there is a lot of freedom that comes with fasting for 16 hours since fasting creates a limited eating window in which to eat all your meals.

The biggest benefit of fasting for 16 hours is entering the autophagy stage, where the body self-heals (also referred to as cellular repair) and it begins to reduce inflammation, boost its immune system, and age healthily.

Studies also show that it might take up to four days for the body to enter this self-healing stage, which is why I recommend that you start with a 12 hour fast and work your way up to a 16 hour fast.

Contrary to popular belief, intermittent fasting is not just skipping breakfast so you’ll need to think about when and what to eat if you have a busy lifestyle.

In addition, having an intermittent fasting meal plan can be highly beneficial if you’re just starting out.

Choose The Best Intermittent Fasting Schedule for You

The best intermittent fasting schedule is one you can maintain without feeling deprived of food.

For some people, stopping their food intake at 7 pm and waiting until 11 am or noon to break their fast is an easy thing to do. For others, especially those who exercise in the morning, holding out for an extra 4 hours can be tough.

If you’re just starting intermittent fasting, consider downloading this full eBook and meal plan.