The 8 Hour Diet – Everything You Need To Know

The 8 hour diet is a form of intermittent fasting.

It is based on setting an 8 hour window where food can be consumed, followed by a 16 hour period of fasting before the next eating window begins.

Unlike the majority of diets that set strict rules and regulations on what to eat and how much, the 8 hour diet is easy to follow and can provide real results with minimal effort.

This style of eating is based on the two primary ideas to benefit health:

  • First is the idea that reducing the time period in which you can eat will inevitably reduce food consumption and therefore cause weight loss.
  • Second is the thought that short-term fasting has unique health effects outside of a reduced caloric intake.

This method of eating also aims to be more in line with our natural lifestyles such as during the days of the “hunter-gatherer”. Clearly from an evolutionary perspective, fasting has been a common practice due to the fact there a much lower availability of food compared to today’s world.

With the popularity in this style of eating making a reappearance, a lot of studies have been conducted to fully analyze the health effects of short-term fasting on metabolic, cardiovascular, and cognitive health.

How To Start The 8 Hour Diet

Most people that follow the diet find it relatively simple compared to other diets.

First, you need to select an 8 hour window when you would like to consume all of your food for that day. This depends quite heavily on your lifestyle and schedule. We recommend trying to move the 8 hour eating window to a time of the day where you tend to get the most cravings.

Some experimentation might be a good way to know what times are best for you.

In addition, although it may be tempting to stock up on junk food during these eating windows (because, technically you can), keep in mind that the best results will come from sticking to nutritious whole foods and beverages during these eating periods.

A high amount of dietary fiber, protein and vegetables during the 8 hour window will considerably help to avoid hunger during the 16 hour fast.

Outside of the eating window, ensure you consuming enough fluid to maintain hydration and feel free to drink calorie-free beverages like unsweetened tea and coffee.

The Potential Benefits of The 8 Hour Diet

Below is a list of every potential benefit that’s backed by credible scientific research:

It Can Initiate Autophagy

One of the main reasons fasting is linked to increased longevity is because it initiates a process called autophagy.

This is a regulatory mechanism within our cells that helps to remove unnecessary or dysfunctional components. It can seen as the “recycling” of cellular components to improve cellular health and these cells remain in their most functional state.

Autophagy has even been referred to as cellular “cleansing”, as the cells undergo important repair processes and can even change the expression of genes [1].

In particular, lab studies have shown that starvation of certain cells can remove toxic molecules and damaged mitochondria [2].

What is also important to understand is that intermittent fasting has evidence to suggest it may improve cellular function by means that are entirely independent of caloric intake, and so they are not purely just a side benefit of weight loss [3].

It Can Increase Cellular Resistance

An important aspect of longevity and inflammation is the ability for your cells to handle stress and prevent damage from harmful substances.

Although more data is needed, the acute stress response induced by short-term fasting may play a mechanistic role in triggering the long-term increase in cellular stress resistance and the ability to repair damaged proteins and cells.

This process is similar to a vaccination, whereby a small exposure to a stressor can upregulate and improve defense systems to protect against larger stressors in future situations.

This metabolic change may effectively protect against the cumulative burden of oxidative and metabolic stresses that are common with modern lifestyles, and reduce rates of aging that are associated with chronic inflammation.

Many of these important changes to cell defense systems are seen at the genetic level, by increasing the production and activity levels of genes that are specifically related to longevity and disease prevention [4].

For example, there is an initiation of the signaling pathways which stimulate the production of protein chaperones, neurotrophic factors and antioxidant enzymes – all of which help cells cope with stress and resist disease.

This large body of research on fasting and cellular resistance has shown the most benefit for preventing neurodegenerative diseases. The mild stress response seems to activate compensatory mechanisms in brain cells, such as the upregulation of neurotrophic factors and heat shock proteins, which could help to prevent Alzheimers and Parkinson’s disease [5].

It May Help With Weight Loss

As the meal frequency on intermittent fasting is heavily reduced, in most cases this leads to an automatic reduction in calorie intake.

Across the plethora of studies on intermittent studies, it seems the protocol, on average, results in a ~20–30% reduction in caloric intake.

Typical weight reductions from intermittent fasting are a loss of 5% bodyweight in 1-3 months, although results obviously vary considerably person-to-person [6] [7] [8].

One of the more interesting questions is whether intermittent fasting has unique benefits to weight loss outside of caloric reduction.

Few mechanisms have been speculated to potential unique actions of intermittent fasting such as:

  • Increasing the release of the fat burning hormone norepinephrine (noradrenaline) which increases resting metabolic rate by ~10% [9].
  • Elevating plasma adiponectin levels (protein hormone) which indirectly stimulates mitochondrial expression and content.
  • Larger thermogenic (heat production) response from an increased adrenaline release caused by the stressors from fasting.

If intermittent does in fact increase energy expenditure, it will simultaneously help you eat fewer calories, whilst burning more calories, thus having a “double effect” for weight loss. Win win. However, a lot more evidence is needed to confirm the effects of fasting on increasing energy expenditure as human studies are severely lacking.

Keep in mind, intermittent fasting will not help you lose weight if you eat too many calories and do not maintain a caloric deficit (eating less than you burn) over time, it is just a tool which may help people achieve this principle.

It May Improve Glycemic Control

Caloric restriction alone can increase the bodies ability to effectively utilize insulin (insulin sensitivity) to control the level of glucose in the blood.

This is important for stabilizing blood glucose levels and avoiding periods of very low or high glucose in the blood which may cause poor health effects such as increasing inflammation [10].

Poor glucose handling efficiency has also been postulated to lead to high levels of non-enzymatic glycation, a form of protein damage [11].

Mechanistically, decreases in glucose concentrations and improvements in insulin sensitivity have been frequently observed in fasting animal studies [12] [13].

Human data is still lacking, although some case reports have demonstrated the effectiveness of therapeutic fasting to reverse insulin resistance, even resulting in cessation of insulin therapy for type 2 diabetes patients [14].

These dramatic improvements likely come as an indirect result of the weight loss that is extremely common during intermittent fasting trials, however the reduced frequency of blood glucose “spikes” during intermittent fasting may also be having a positive effect.


The 8 hour diet involves eating only during an 8 hour window and fasting for the remaining 16 hours.

A lot of new research is showing that it may be a great way to reduce inflammation and increase longevity, mainly due to the activation of a process called autophagy.

Those wanting to lose weight may also benefit from such an eating plan as it reduces meal frequency and most people find it simple to follow.