There are a number of different types of intermittent fasting (highlighted below), but they all serve the same purpose—to allow your body time without food to spend more of its energy on internal healing and repair—something that cannot happen when you’re constantly in a fed state.

Technically, you don’t need to change anything about your diet to benefit from intermittent fasting, which makes it very appealing to many people.

It’s also for those who want that extra edge to burning fat while maintaining their muscle (shouldn’t we all?).

It’s completely safe to do and provides enormous benefits so it’s really just a matter of committing to it, trying it out, and seeing if it’s something you want to do regularly.

Studies on animals are being done by Dr. Mark Mattson and colleagues at the National Institute on Aging. The findings from these studies suggest that animals age slower and live longer when they consume fewer calories. The research is showing that this effect can be achieved by eating less each day, or by fasting on intermittent days. 

Here’s a recap, plus a few more mechanisms through which fasting increases “lipolysis” (fat burning) in the body:

I’m very aware that the mere mention of the term fasting terrifies many people, conjuring up images of intense suffering and starvation. They picture themselves waking up in the morning and starting their 24-hour timer, anxiously counting down the milliseconds until they can have the first bite of their post-fast meal. Others can’t even fathom the idea of going a full day without food. 

It really doesn’t have to be so awful, and there’s an approach that actually makes it quite doable.

What makes it all a whole lot easier is simply making the decision to do it. 

Most people have a tough time without food because they’re constantly thinking about what they’ll eat next. In the middle of a stressful day, that just feels like too much to handle, as the satisfaction that comes from a delicious meal—even one that’s not good for you— helps people soothe their blues away. When that food isn’t there, they start panicking.

When you consciously make the decision that tomorrow will be a fast day, 

you activate a new mechanism inside yourself. You’re forced to let your innards recharge while you reflect on the bad eating habits with which you’ve been self-medicating. Fasting is such a profound tool for deep change. No wonder people have been turning to it for centuries.”

There you go. That’s all you need to start intermittent fasting.

Although a lot of the research on fasting has used “alternate day” fasting where you basically don’t eat every other day (which is crazy if you ask me), you can still see noticeable fat loss results with just a 2 days of fasting per week.

So finish dinner and start your fast thereafter. Remember, when your body is in a fasted state is starts to rely more on its fat stores for fuel.

Thus, it helps you become a fat burner instead of sugar burner who is constantly craving food. It’s a very freeing process.

At any point of your day, do 5-10 minutes of high intensity interval training to increase your body’s release of catecholamines. These are your fight- or-flight hormones—specifically, epinephrine and norepinephrine—released by the adrenal glands in response to stress like high intensity training.

One of the roles of these hormones is to break down stored fat in your body into free fatty acids that can then be converted into energy. This intense exercise also depletes your glycogen stores much more readily.

As glycogen is depleted, your body must rely further on burning fat for energy.

You do not get this catecholamine response with low-intensity exercise. (If the word intensity scares you, don’t be alarmed. You’ll only be doing 5 to 10-second bouts interspersed with nice and easy recovery.)

And if you want to take your fat burning to the next level, then after you finish your intervals, spend 30 minutes or more going for a nice easy walk or bike ride to burn up those free fatty acids (from broken-down fat) that have flooded into your bloodstream.

Post-workout is when your body, since it’s recovering, really relies on those fats for fuel.

For instance, a 2008 study showed that even though carbohydrates were the predominant fuel source during the actual workout, for more than 3 hours afterwards, fats became the main contributor to energy. 

Basically, the most fat was burned post-workout. But again, workout intensity sets the stage for this to happen.

So, to really take advantage of this fat-burning window, I strongly recommend following your high intensity intervals with 30 minutes (or more) of low-intensity cardio like walking.

This will help shuttle those free fatty acids floating around in your bloodstream into your muscles to be burned as fuel.

When you finish your fast you need to pretend that your fast never happened. No compensation, no reward, no special way of eating, and no all-out binges.

The minute you decide to stop fasting, simply wipe the fast from your memory, and eat the exact way you would normally eat at that specific time of the day (while eating responsibly of course).

If you end your fast at dinnertime, have dinner. If you end your fast at 4:00 PM and you don’t typically have dinner until 6:00 or 7:00 PM, then have a light snack… but nothing larger than you would normally have at that time.

There is no magic way to end your fast. The absolute best thing you can do is simply pretend your fast never happened and begin eating in the exact way you would normally eat at that specific time of day.

One thing I have noticed though with many clients is that they tend to “crave” healthier foods at the end of their fast.

As a result, they end up choosing a green smoothie or a healthy snack instead of devouring a large pizza (as you might think would happen after not eating anything all day).

For the vast majority of the healthy population, we are easily able to maintain healthy blood sugars that are neither too-high nor too-low in a whole range of different situations, including fasting and intense exercise.

In research examining the effects of a 24 hour fast, it was found that fasting did not cause blood sugar levels to dip below 3.5 mmol/Liter, meaning that during the entire 24 fast, blood sugar slowly lowered itself, but remained at normal non-hypoglycemic levels. 

As long as you are doing some form of resistance training at least two or three times a week you will not lose muscle since intermittent fasting actually increases growth hormone, which helps preserve muscle.

One thing you may notice is if you work out on day in which you’re fasting, your energy levels may be a little lower.

That’s because the workout will be tapping into lowered glycogen reserves, which means you may fatigue sooner than on a traditional “eating” day.

However, exercising, especially for short durations at high intensity, in a fasted state is a secret weapon I would strongly encourage you to explore as it will accelerate fat loss tremendously (more on that below).

Additionally, your hunger hormone ghrelin responds to a lack of food in the stomach, which will naturally have it firing on all cylinders, making your brain think you’re starving.

Hunger pangs usually dissipate after your first 2-3 fasts as your body adjusts.

That also doesn’t mean drinking diet soda is ok, because it’s not. Just drink water or herbal tea.

Some people tell you that black coffee is ok to drink during a fast but I wouldn’t advise that. Yes, the caffeine in the coffee will skyrocket your epinephrine which can assist with fat loss, but since I don’t advise drinking coffee in general, you’re better off without it, especially when its caffeine isn’t buffered by food.

Instead, focus on drinking plenty of water and/or any herbal teas that you enjoy without the use of milk, sugar, or sweeteners. Remember, this is a day of “rest” for your body so that means no calories of any kind.

This may also help prevent your body from developing sensitivities to commonly consumed supplements and ingredients that can occur with continued consumption of literally any food product.

Some women choose to do TWO 24-hour fasts per week and have seen great results doing so, but I would say that’s the maximum.

So when you are fasting, more blood is travelling to your body fat, presumably to help move it to your muscles where it can be burned as a fuel. Due to this increased travel to your body fat, vasoconstricton occurs in your fingertips and sometimes toes to compensate.

This is the biggest area of controversy when it comes t0 intermittent fasting.

Those who caution women against intermittent fasting state that studies show that it negatively impacts fertility. And that’s true.

Unfortunately, what most of these people fail to realize is that ALL of these studies use “alternate day” fasting protocols where women are literally eating nothing every other day!

No wonder their hormones get messed up and have fertility issues.

Remember, I’m advising 2-3 day per week fast much safer and I’ve yet to see any negative effects in the thousands of women that I’ve helped with intermittent fasting.

Not to mention you're not fasting like most people. The foods and meals you're eating are hormone balancing and metabolism enhancing.

There is some research that looked at the effect of short-term fasting on the menstrual cycle of women.

These research studies found that despite the metabolic changes that occur during fasting, even fasts as long as 72 hours do not seem to have an effect on the menstrual cycle of normal cycling women.

Interestingly, even longer fasts have been shown to have little impact on the menstrual cycle of normal weight women.

There is research, however, to suggest that longer fasts (72 hours) can affect the menstrual cycle of exceptionally lean women (body fat levels well below 20%).

Overall, there’s a lot of research (even some of the “alternate day” studies) that show intermittent fasting to be safe, healthy, and effective at burning fat in women of all shapes and sizes.

But again, we’re not going crazy with this and only fasting for no longer than 16 hours, no more than 3 days per week.

Nonetheless, if you’re a woman and still unsure whether or not intermittent fasting is right for you, then my advice would be to inch yourself into it so that you’re fasting for 8-10 hours at a time. Then gradually increase that length of time as you see fit.