What is Intermittent Fasting?
Intermittent fasting is an eating approach where you take an extended break from consuming food for a specific duration. This way of eating has been done throughout history, however, in recent times has increased in popularity due to the growing body of evidence surrounding the health benefits.
The main difference intermittent fasting offers over other diets is that it doesn’t eliminate certain foods or food groups. It also doesn’t focus on specific nutrients. While some intermittent fasting methods may stipulate a restriction on your calorie intake during the fasting window, it’s the timing of your fast that really matters.
What is the 16:8 Method?
The 16-hour fast is commonly referred to as the “16:8”, “The 8-hour diet” or “Leangains” intermittent fast. This involves daily fasting for 16 hours and consuming food during an 8-hour eating window.
This intermittent fasting plan was first made popular in 2007 by bodybuilder Martin Berkhan who wrote extensively about it on the website www.leangains.com. Berkhan wrote predominately about the health benefits of exercising during the fasting window and consuming most of your calorie intake in the time post-workout.
For many, this fast is a preferred method as it still allows ample time to consume two to three meals during the day before your 16-hour window. The flexibility of the 16:8 makes this fasting diet relatively easy to follow, especially for those who haven’t tried a fast before or don’t want to count their calorie intake.
How to do the 16:8 Intermittent Fast
The 16:8 intermittent fasting diet is a daily regime. This means you pick your fasting window and adhere to this schedule until you decide you no longer want to adopt this way of eating.
If you choose this method of intermittent fasting, most people will say the easiest approach to take is to skip your breakfast and eat your first meal later in the day.
For example, you might eat from 10:00 am to 6:00 pm and then fast from 6:00 pm until 10:00 am the next day. During the 8-hour feeding window, you’ll eat your desired daily calories. Other ways you could structure your eating time on 16:8 plan are:
- 8:00 am to 4:00 pm
- 9:00 am to 5:00 pm
- Noon to 8:00 pm
How you schedule your fasting and eight-hour window for eating is really up to you depending on your lifestyle. What’s important is that you’re fasting for 16 hours and only consuming food within the 8 hour period. Although it is recommended for optimal digestion to avoid eating food for 2-3 hours before bed.
Eating within the feeding window is important to maintain a stable blood sugar balance and avoid the symptoms of excessive hunger. The choice of food will also play a role in achieving your health goals, particularly if you’re wanting to lose body fat.
Consuming a healthy balanced diet is recommended, especially if you’re wanting to avoid weight gain or lose body weight. While calorie restriction is not a focus on this intermittent fasting method, you still need to remember the type of food matters and your overall caloric intake needs to be less than you burn for weight loss.
For those who exercise, most benefits are seen when you train fasted. In other words, schedule your workout right before you eat your first meal. This should be your largest meal in the eight-hour feeding window and you may choose to follow this up with a small meal or scheduled snacking in the time remaining.
A Sample Day of a 16:8 Fast
7:00 am – Wake and drink 500 mL of water with lemon
8:00 am – Drink 500 mL of water and 2 herbal teas
9:00 am – Drink 500 mL of water and workout
10:00 am – Eat first meal – largest of the day
2:00 pm – Eat second meal – moderate-sized
6:00 pm – Eat second meal – moderate-sized
Tips for Starting Your 16:8 Fast
To help you start your first 16:8 fast and successfully stick to it for an extended period of time, follow these tips.
Before you start:
- Select a fasting time that suits your lifestyle commitments and your exercise regime
- Define your health goal and measure to collect a baseline
- Choose a time to start your fast when you can strictly adhere to it for at least 14 days
- If you are overwhelmed or concerned about fasting, speak to a health professional such as a dietitian or nutritionist or engage a coach to help you navigate the process
During your fast:
- Focus on nutrient-dense whole foods and healthy portions
- Increase your non-starchy veggie and fibre intake including whole grains
- Avoid and limit processed or junk foods
- Keep hydrated by drinking water and herbal tea throughout your fast
- Exercise before or during your feeding window
- Practice slow and mindful eating when consuming meals
- If you find the feeding window is too strict, extend it by an hour
Not Seeing Results?
If after two weeks you’re not seeing any positive changes, make one small change to your way of eating. This may be moving the feeding window by an hour or two. It could be changing the time you exercise to right before your first meal rather than during your feeding window. Perhaps you need to adjust the nutrient timing or consume fewer calories.
Health Benefits of 16:8
The benefits of intermittent fasting have been studied for decades although there is a huge body of research into just the 16:8 method.
Intermittent fasting, in general, can result in some fat loss in as little as two weeks of adopting the eating method due to your body’s ability to start fat burning.
A 2017 study published in the International Journal of Obesity found obese men who intermittent fast achieve greater weight and fat loss than regular calorie restriction.
Adhering to a resistance training regime while following the 16:8 intermittent fasting method may lead to greater weight loss and help you maintain your muscle mass.
The success of the 16:8 method may also come does to when you consume your calories during your eating window. A recent study found more favourable outcomes may be achieved by eating one large meal earlier in the day and restricting your caloric intake in the evening.
Early studies into intermittent fasting suggest the eating method may improve metabolic profiles and reduce your risks of chronic illness such as obesity, heart disease and type 2 diabetes. However, more research is required in this area.
A study published in 2018 found the 16:8 method may help to reduce blood pressure in overweight and obese adults. Fasting may also prove more promising than regular calorie restriction, such as a low-carb diet, in reducing glucose levels and fasting insulin levels in pre-diabetics.
Animal studies have also found that 16:8 decreases the risk of cancer and non-alcoholic fatty liver disease.
Intermittent fasting may also have positive effects on your cognition, improving brain function, memory and reducing brain fog.
Fasting for 10-16 hours has been shown to have a protective effect on your neurons due to the production of ketones as your body utilises body fat for energy. This has been shown to help protect memory and improve learning ability.
Cognitive, sensory-motor function and physical performance may also be improved when adopting fasting and an exercise protocol. Although more research is needed in these areas.
Studies into the area of longevity and fasting are limited although it’s plausible the positive effects on metabolic health, blood sugar levels, weight control and inflammatory markers could help you achieve a longer lifespan.
Several animal studies suggest restricting calories through short-term, repeated hours of fasting results in an increased life span. This may be in part due to the reprogramming of stress and metabolic resistance pathways.
Intermittent fasting, including the 16:8, may help to delay aging and be used as a preventative and treatment measure of chronic disease.
Pros of the 16:8 Fasting Method
There are many potential benefits of the 16:8 intermittent fasting method:
- The daily schedule makes it easy to adhere to as it’s the same each day
- You can adjust the feeding and fasting time to suit your lifestyle
- You don’t have to calorie count
- Most of your fasting can occur while you’re asleep
- May offer plenty of possible health benefits
Cons of the 16:8 fasting method
There are some potential cons of the 16:8 fasting method:
- 16:8 doesn’t replace healthy nutritional basics
- People can binge or overeat during the eight-hour feeding window
- Not suitable for everyone
Side effects and risks of the 16:8
As with any intermittent fasting or dieting regime, there are some associated side effects to take into consideration before you dive in.
Most of the more common side effects experienced on the 16:8 are short-term and subside as your body adjusts to the fasting period. Others can be easily overcome with careful planning. These include:
- Tiredness or weakness
- Overeating during the 8-hour feeding period
- Heartburn due to overeating
16:8 is Not for Everybody
It’s important to note intermittent fasting including the 16:8, is not for everyone. If you are pregnant, breastfeeding or under 18 years old, you should not fast. It’s also not for you if you are underweight or have a history of an eating disorder or disordered eating.
Intermittent fasting or short-term calorie restriction may also not be suitable for those with depression or anxiety or who have an underlying health condition such as diabetes or low blood pressure. If you are taking any prescribed medications, it is recommended you speak with a health professional before you try any fasting method.
The Bottom Line
Due to the flexibility and simplicity of the 16:8, it can be the ideal introduction for those interested in trying a fasting method. The potential health benefits of intermittent fasting include weight loss, body fat loss and reduced risk of some diseases such as type 2 diabetes.
If you choose to adopt the 16:8 intermittent fasting method, it’s important to schedule your fasted state around your training and lifestyle commitments.
It is equally important to still focus on what you’re eating during your 8-hour window to minimise side effects and enhance results, particularly if you have a weight loss goal.
The 16:8 form of intermittent fasting can reap many benefits, but it’s not for everyone. Those with existing medical conditions or any concerns should consult with a health practitioner before starting any periods of fasting.
Explore in more detail
- A Beginner’s Guide To Intermittent Fasting
- A Guide To The 16:8 Fast
- A Guide To The 20:4 Fast
- A Guide To The 5:2 Fast
- Intermittent Fasting And Exercise
- Intermittent Fasting And Hormone Balance
- Intermittent Fasting And Keto
- Intermittent Fasting And Type 2 Diabetes
- Intermittent Fasting And Weight Loss
- Intermittent Fasting: Tips To Starting Your First Fast
- Side Effects Of Intermittent Fasting
- Tips For Intermittent Fasting Success
- Top FAQs Of Intermittent Fasting