12/12 vs. 16/8 Intermittent Fasting: Everything You Need To Know

Intermittent fasting or time-restricted eating methods are gaining traction. Healthcare professionals often prescribe intermittent fasting to help tackle obesity and its associated ailments. Several protocols exist for practicing intermittent fasting. [1]

The effectiveness of different intermittent fasting plans has been debated for a long time. This article compares two of the most popular intermittent fasting plans (12/12 and 16/8) and helps you pick the one best for you.

What is Intermittent Fasting? 

Before getting into the nitty-gritty of the topic, let us understand intermittent fasting and what makes it effective against so many life-threatening ailments. Intermittent fasting refers to the time-restricted eating practice where people consume food (calories) during a certain period and fast for the rest of the day.

Many people often associate intermittent fasting with calorie counting, which is untrue. A person following an intermittent fasting plan doesn’t have to limit his caloric intake during the eating window. Although notably, overeating during an eating window is not advisable.

When we consume food, our body breaks it down and converts it into its primary energy source, glucose. Glucose is then converted into glycogen, stored in the liver, and used when the body needs energy. Often, for people who lead a sedentary lifestyle and remain in a caloric surplus, this stored glycogen turns into excess body fat. This excess fat is stored in several body fat reserves, leading to weight gain and obesity.

During intermittent fasting, our body is short on calories, as we cannot consume food during the fasting window. This is when the body starts using the stored glycogen from the liver to produce energy. When glycogen stored in the liver is exhausted, the body starts to break down the stored fat to produce energy to maintain ‘homeostasis.’ This process is known as ketosis, where our body uses fat as fuel. 

Following this time-restricted diet for a prolonged period can help you lose fat and tackle obesity. Additionally, fasting has several other health-related benefits, as discussed below.   

What Happens During 12/12 Intermittent Fasting?

The 12/12 intermittent fasting program involves eating in a 12-hour window and fasting for the remaining 12 hours. A 12-hour fasting window can seem daunting to people new to intermittent fasting. However, it is not the case. A 12-hour fast can be easily achieved when we consider that most people sleep for six to eight hours daily. One can follow the 12/12 intermittent fasting plan without skipping any meals.

The biggest benefit of a 12/12 intermittent fasting plan is that it aids in the initial fat loss process for obese people. During the initial fasting period, the body exhausts the stored glycogen reserves and is forced to enter ketosis by the end of the fast.

Although not many studies suggest that fasting for 12 hours leads to other, more pronounced benefits, people who regularly practice the 12/12 fasting routine might notice a boost in their metabolism. Overall, the 12/12 fasting routine can be a starting point for people getting into fasting or struggling with calorie restriction.

What Happens During 16/8 Intermittent Fasting?

The 16/8-hour fasting plan is one of the most popular intermittent fasting methods. This is often considered the ideal fasting method by many experts. Although it is a bit more difficult than the 12/12 protocol, it is still achievable. People who follow the 16/8 intermittent fasting plan often skip one meal (usually breakfast) and only consume two meals (lunch and dinner).

Since the fasting window in the 16/8 intermittent fast is longer than the 12/12 fast, you will have a longer duration of ketosis. This is very important for fat loss as it encourages the body to use stored fat as energy. When we consume food, our insulin levels rise dramatically; this is one of the major reasons for blood sugar spikes. Fasting for 16 hours at a time is a great way to manage insulin release, preventing unnecessary blood sugar spikes.

One of the most significant advantages that 16/8 intermittent fasting has over 12/12 intermittent fasting is its effect on the body at the cellular level. Fasting for 16 hours a day promotes a process called cellular autophagy. In this process, our cells consume the weak and diseased cells, which are then replaced by newer cells. This process is responsible for cell and tissue regeneration and slowing aging.

Some studies also indicate that fasting for 16 hours daily can boost brain health and cognition. Overall, the 12/12 intermittent fasting plan is better for people new to fasting, but the 16/8 fasting plan is much more advanced and delivers more benefits.

Benefits of Intermittent Fasting

Let us now look at some of the evidence-based benefits of intermittent fasting. These benefits are not particularly related to the 12/12 or 16/8 intermittent fasting methods but are a more general list of benefits of intermittent fasting.  

Weight Loss 

Weight loss is one of the most prominent benefits of intermittent fasting. This is because, as a whole, intermittent fasting targets the body’s built-up visceral fat and forces it to break down. Another aspect of intermittent fasting is the hormonal activity it promotes, which leads to fat loss.

Some studies suggest that intermittent fasting not only controls frequent insulin spikes but also increases the levels of hormones like HGH and norepinephrine. These hormones promote fat breakdown and help improve the body’s metabolic rate. [2]

Intermittent fasting often requires us to skip meals, leading to lesser overall calorie consumption. So, intermittent fasting helps us burn more calories while limiting our calorie intake, leading to an effective caloric deficit.

Improves Heart Health

Although intermittent fasting does not directly affect our heart health, it has been shown to be effective in improving several factors that promote heart health. These factors include blood sugar, blood pressure, inflammation levels, etc.

Some studies have shown that fasting can lead to better cholesterol management. It helps decrease the bad LDL cholesterol and triglyceride levels, often the prime reasons for artery blockage and stroke. Furthermore, it has been seen that fasting increases good HDL cholesterol metrics. [3]

Reduces Inflammation

Inflammation is not bad for our body, as it is the body’s defense mechanism against injury and disease. But often, inflammation leads to severe oxidative stress, which can be responsible for various life-threatening autoimmune diseases and early aging.

Oxidative stress is related to free radicals and unstable molecules in our bodies. These free radicals often react with our DNA and damage it. Studies have shown that intermittent fasting can help reduce these free radicals and enhance the body’s resistance to oxidative stress. [4]

May Boost Brain Health

Research shows that fasting for longer durations can increase cognitive response and enhance memory. Additionally, fasting helps reduce blood sugar, blood pressure, inflammation, etc. Medical professionals believe that these factors combine to boost our overall brain health. Several animal-based studies have shown that fasting can improve brain function and promote the growth of newer nerve cells, leading to better brain function.

Fasting increases the secretion of a special brain hormone called a brain-derived neurotrophic factor (BDNF). BDNF deficiency is often linked with several brain-related ailments, like depression. Some early studies also indicate that fasting may prevent brain damage and stroke. [5]

Promotes Insulin Sensitivity

Type 2 diabetes is a major modern-age health problem. Poor insulin sensitivity is a critical factor for high blood sugar and diabetes. When we consume food, our insulin levels increase to help us digest the food. It also spikes our blood sugar levels. Frequent insulin spikes can cause the body to eventually resist it, leading to irregular blood sugar levels and type 2 diabetes.

Intermittent fasting is proven to control the frequent insulin spikes in our body, which can help decrease overall insulin resistance. Hence, intermittent fasting can be a great tool for people to prevent the onset of diabetes and insulin resistance in general. [6]

Promotes Cellular Health and Cell Repair

One of the fascinating benefits of intermittent fasting is cell repair. During longer durations of intermittent fasting, the cells in our body undergo autophagy.

Autophagy is the process by which the cells in our body consume other weaker and diseased cells and cell organelles. These are then replaced by newer, more healthy cells. This phenomenon leads to better cellular health and helps slow our aging process.

How To Perform Intermittent Fasting Safely?

Intermittent fasting plans, with their various benefits, can be a tempting proposition for many people. However, you must not perform any dietary change without medical consultation. Here are some tips to consider before starting intermittent fasting:

• People must consume adequate water while performing an intermittent fast, as it is not a dry fast, and a lack of water can lead to dehydration and other complications.
• Fasting for long durations can cause our bodies to lose electrolytes, especially if we are active during fasting. Hence, consuming calorie-free electrolyte drinks and supplements while fasting is important.
• Folks struggling with hunger pangs can consume zero-calorie drinks like coffee, tea, lemon water, etc.
• Teenagers or older adults must not perform intermittent fasting, as it can stunt their growth and cause muscle loss.
• People with underlying health concerns like heart issues and type 2 diabetes must avoid intermittent fasting.
• Pregnant or breastfeeding women must also not fast, as it can cause several complications.

Frequently Asked Questions

Is a 12-hour fast as good as a 16-hour fast?

While there is no scientific consensus on how long a fast should be, many people use the 16/8 intermittent fasting method. If you’re new to fasting, it’s best to start with a 12-hour fast.

Both types of fasts can help with weight loss.

Is a 12/12 intermittent fast effective?

Yes, after ten weeks of following the 12-hour intermittent fasting routine, most people experience weight loss of an average of 7–10 pounds. However, everyone has a different metabolism, and results might vary. 

What is the difference between fasting for 12 hours and 16 hours?

The main difference between the 12/12 diet and the 16/8 diet is that the former has a 12-hour eating window and a 12-hour fasting window, while the latter has an 8-hour eating window and a 16-hour fasting window.

Final Thoughts

Intermittent fasting, in general, is a revolutionary process for people dealing with obesity or wishing to lose body fat. The added health benefits make it even more attractive. Whether a person prefers the 12/12 fast or the 16/8 fast doesn’t matter. It is more down to personal choice and the comfort level of the person performing the intermittent fast.

References

1. Arnason, T. G., Bowen, M. W., & Mansell, K. D. (2017, April 15). Effects of intermittent fasting on health markers in those with type 2 diabetes: A pilot study. PubMed Central (PMC). 
2. Teruya, T., Chaleckis, R., Takada, J., Yanagida, M., & Kondoh, H. (2019, January 29). Diverse metabolic reactions activated during 58-hr fasting are revealed by non-targeted metabolomic analysis of human blood – Scientific Reports. Nature. 
3. DONG, T. A., SANDESARA, P. B., DHINDSA, D. S., MEHTA, A., ARNESON, L. C., DOLLAR, A. L., TAUB, P. R., & SPERLING, L. S. (2020, April 21). Intermittent Fasting: A Heart Healthy Dietary Pattern? PubMed Central (PMC). 
4. H., Pizzino, G., Irrera, N., Cucinotta, M., Pallio, G., Mannino, F., Arcoraci, V., Squadrito, F., Altavilla, D., & Bitto, A. (2017, July 27). Oxidative Stress: Harms and Benefits for Human Health. Oxidative Stress: Harms and Benefits for Human Health. 
5. Björkholm, C., & Monteggia, L. M. (2015, November 11). BDNF — a key transducer of antidepressant effects. PubMed Central (PMC). 
6. Intermittent fasting vs. daily calorie restriction for type 2 diabetes prevention: a review of human findings. (2014, June 12). Intermittent Fasting Vs. Daily Calorie Restriction for Type 2 Diabetes Prevention: A Review of Human Findings – ScienceDirect. 

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