What Is Intermittent Fasting?
If you’re considering intermittent fasting, consider this: You’ve probably already done it! Have you ever had an early dinner, gone to sleep, then ate breakfast around 10 am the next day? If so, you have probably fasted for more than 16 hours!
In fact, fasting has been utilized throughout human evolution. Instead of grocery stores, our ancient ancestors were hunting and gathering – which is far from making a restaurant reservation! There were no guarantees, which means they often went extended periods of time without eating.
In essence, that is how it works: cycling between periods of fasting and eating.
There are plenty of different ways to practice IF, which makes it easy to find a plan that works for you. Unlike restrictive diets, intermittent fasting will have you focus on when you eat – rather than what you eat. It’s surprisingly simple and allows you to have flexibility within your diet. It requires no special meal preparation, no restriction of certain food groups, and you can do it from anywhere!
Intermittent Fasting Benefits
While many turn to IF as a way to lose weight without having to count calories or follow a certain diet, studies have also shown that there may be other benefits.
In addition to potential weight loss, the benefits may include:
- Improving insulin sensitivity (1)
- Reducing blood sugar and/or insulin levels (1)
- Reducing inflammatory markers (1)
- Improving resting heart rates and blood pressure (2)
- Lowering total cholesterol, LDL (low-density lipoprotein), and triglyceride levels (3)
- Increasing total HDL (high-density lipoprotein) levels (3)
- Improving thinking and verbal memory as well as protecting against Alzheimer’s disease (4)
It’s important to note that these benefits may depend on the type of fasting plan and the duration the plan is followed and results may vary based on the individual.
How does intermittent fasting work?
The general concept is pretty simple, really. When the body goes without food for several hours, it exhausts its carbohydrate stores and begins burning fat for fuel. During intermittent fasting, several things can also happen on the cellular level. Your body’s hormones can adjust to make stored body fat more accessible, your body’s cells can initiate repair processes and change gene expressions (5), and insulin sensitivity and insulin levels even drop dramatically.
While there are different ways to practice IF, they are all based on carving out regular periods of time to fast and to eat. For example, one way to practice it is to eat only during an eight-hour period each day and fast for the remainder. Another is to eat only one meal a day for two days a week and eat regularly on the other five days.
Intermittent Fasting Plans
First and foremost, it’s important to pick a plan that works for your lifestyle and one that you can sustain. It’s advised that you stick to a certain plan to ensure that you are reaping all of the benefits of it.
An easy way to start is to use your sleeping hours as a majority of your fasting hours. For example, if you stop eating 4 hours before bedtime, then sleep for 8 hours, then begin eating 4 hours after you wake up, you will have fasted for approximately 16 hours. This is what we call a 16:8 fasting plan, meaning you are fasting for 16 hours and eating during an 8-hour window.
This is a popular method since it puts the bulk of your daily calorie consumption during the middle of the day.
Examples of 8-hour eating windows include:
- 9 a.m. to 5 p.m.
- 10 a.m. to 6 p.m.
- 12 p.m. to 8 p.m.
Within intermittent fasting hours, people can eat their meals and snacks at times that are convenient for them. The 16:8 plan is often considered the simplest and most sustainable way to start, especially if your 16-hour fasting period includes the time spent sleeping.
If you have practiced the 16:8 diet for a few weeks and find it easy and feel good during your fast, then you could consider trying more advanced fasts.
Other popular plans include:
- Eat-Stop-Eat: Fast for 24 hours, once or twice a week.
- The 5:2 Diet: Consume only 500–600 calories on two non-consecutive days of the week, then eat as you normally would the other five days.
- The warrior diet: eat nothing for 20h hours, then have a four-hour eating period.
As with any change in dietary habits, it’s important to consult your doctor or dietitian first.
What to eat during intermittent fasting?
While IF plans do not specify which foods to eat and avoid, it’s still important to consume a balanced and varied diet that is rich in important nutrients.
A balanced diet can include:
- Fruits and vegetables
- Whole grains
- Lean proteins
- Healthy fats
Higher fiber foods like fruits, vegetables, and whole grains can help you stay fuller and feel more satisfied between meals. Healthy fats and proteins can also help.
You will also want to ensure that you’re consuming a variety of vitamins and minerals, either via food or supplements, to help you meet your daily needs.
IF plans permit the consumption of calorie-free drinks, like water and unsweetened tea or coffee. It is important to drink plenty of fluids to avoid dehydration. Get insights into what to drink during intermittent fasting.
Intermittent Fasting Side Effects
When it comes to the side effects, hunger is the most common. Constipation and headaches can also be common, and they tend to disappear over time. Other possible side effects can include dizziness, heartburn, and muscle cramps, which are associated with the so-called "keto flu".
Most side effects are manageable, and they do not mean that you should stop your fast. If you feel unwell, though, and are overly dizzy, especially weak, or you have other severe symptoms, then you should break your fast.
That being said, intermittent fasting is certainly not for everyone. If you fall into any of these categories, consult your physician:
- Have an underlying health condition
- Have a history of disordered eating
- Have a history of mental health disorders
- Are advanced in age
- Are pregnant or breastfeeding
In summary, IF is convenient and flexible. In fact, you may already be practicing some form of IF without realizing it! You can pick a plan that works for your lifestyle and continue to eat a healthy, balanced diet while reaping the many benefits of intermittent fasting.
Do you think it could work for you?