Fasted Weight Training: The Major Rules!

As you know, when it comes to building muscle, the more food you eat, the bigger you get, right? Well, not exactly.

Not in a muscle-building sense at least.

If you consume copious amounts of food your daily caloric intake will of course increase, and you’ll gain weight as a result.

The majority of the weight you gain, even if you’re training hard, will be from body fat.

In a bodybuilding sense, gaining fat is the last thing you want.

Muscle, yes, but fat, absolutely not.

There is, however, a misconception that all bodybuilders need to consume an enormous meal packed full of protein and carbs before they work out if they wish to get a good session in.

New research suggests that not only may this not be necessary but that it may even be detrimental to your training and your gains.

Fasted weight training is very much the hot topic of the fitness community at the moment, but is it really as beneficial as experts believe?

There’s only one way to find out.

Here’s a look at your ultimate guide!

What Is Fasting?

Years ago, doctors and nutritionists swore blind that fasting and starvation were detrimental to your health, especially from an athletic standpoint.

It was believed that fasting would result in your body entering ‘starvation mode’ resulting in a suppressed metabolism and muscle atrophy caused by catabolism.

We’ve come a long way these last few years, and we now understand that fasting is actually strongly believed to be extremely beneficial.

Believe it or not, but each and every single one you fast, every single day/night.


Simple, by going to sleep.

When you go to sleep each night, you likely don’t go to sleep on a full stomach, which means that you likely go roughly 10 – 14 hours without eating any food at all.

The first meal you eat is breakfast.

The name is literally break-fast because by eating it that’s what you’re doing, you’re breaking your fast.

Lately, intermittent fasting diets have proved to be hugely popular in the bodybuilding community.

Whenever you consume some food, your body will break it down into much smaller molecules which are then absorbed into the bloodstream.

Once in the bloodstream, your pancreas then produces and secretes insulin.

Insulin is a hormone that is responsible for shuttling glucose and nutrients in your bloodstream into your cells to be used for energy.

Insulin is literally the key that unlocks these cells.

As you digest your food, you are technically in a fed state, even if you still feel peckish.

This results in your insulin levels remain elevated for a good 3 – 6 hours, depending on what you ate and how much you ate.

After the last remnants of your meal have been digested, you’ll find that your insulin levels return back to normal.

Once this occurs, you are now in a fasted state.

In terms of weight training, it’s important to understand precisely what it means to be in a fasted state.

You see, people often mistake hunger for being in a fasted state.

You could literally eat a sandwich and feel hungry an hour later, but this doesn’t mean that you’d have fasted.

Your insulin levels would still be elevated, and you’d still be digesting the sandwich.

It would simply mean that you were hungry.

Now, eating your supper at, say, 8 pm, and going to sleep at 11 pm would mean that when you woke up at 7 am, you would definitely be in a fasted state.

I Thought Fasting Meant Starving Yourself For Days?

Fasted Weight Training

If you were under the assumption that fasting means that you starved yourself for days then don’t worry, you’re definitely not alone.

People often assume that intermittent fasting means that you eat nothing for days at a time and drink nothing but lemon water and plain green tea.

The truth of the matter is that intermittent fasting, and other similar fasting protocols, simply require you to go for a number of hours without eating, in order to truly ensure that you’re entering a fasted state.

One common form of intermittent fasting is the 16:8 protocol.

This basically means that for 16 hours of the day you fast, and for 8 hours you have an eating window.

That may sound extreme, but your 16 hours of fasting will include sleeping, so really, you only abstain from food for around 7 – 9 hours, depending on how much sleep you normally get.

Is Fasted Weight Training Safe?

One of the most common questions is whether or not it is safe to lift weights whilst in a fasted state.

The answer to that question is an emphatic YES!

You can do virtually anything in a fasted state, it just means that you’ll probably feel a little hungry as you do it.

Some people find that they feel physically and mentally lethargic whilst training in a fasted state, which is why it’s important to take your time and focus when training, which really, you should be doing anyway.

Proving you aren’t looking to bench press a personal best, or set a new squat record, as long as your intensity is moderate and you ensure that you’re able to handle the weights you’re lifting, being in a fasted state will not put you in any more or less dangerous than training on a full stomach.

Can You Build Muscle In A Fasted State?

So, now the million-dollar question: Can you build muscle in a fasted state.

The answer to that question is again yes!

Studies have found that weight training in a fasted state will indeed help to promote the growth and repair of lean muscle tissue.

Now, we know that protein is essential for muscle growth and repair, so starving yourself for 24 hours would indeed be detrimental to your training.

Lifting whilst in a fasted state like the one we mentioned above, however, will indeed enable you to build muscle.

You see, in order to build muscle, you must first break down your existing muscle tissues and fibers.

You do this through weight training.

You build muscle when you rest, as your body uses proteins and other nutrients to repair and rebuild the previously damaged muscle tissues.

In order to build muscle, you need to first break it down, so providing you are training, when you do next eat a meal spike your insulin levels and put your body in a fed state, your body will use these nutrients to build muscle.

How Soon After Training Should I Eat?

This is where it pays dividends to understand when to eat after training, so pay attention.

Assuming that you’re following the 16:8 IF diet protocol, it is recommended that you time your workout so that it finishes very close to when your feeding window opens.

So, say for example, that you fast from 10 pm until 2 pm the following day, this means that your feeding window will be from 2 pm until 10 pm.

If you insist on training fasted, we’d recommend timing it so that your workout finishes around 1 pm – 2 pm.

This is so that you can eat/drink some protein as soon after lifting the weight as possible.

The primary reason why people perform it is so that they can burn fat as they build/maintain lean muscle.

If you are lifting weights and then eating or drinking nothing but water for several hours after training, you’re breaking the muscle tissue down but giving your body nothing to facilitate protein synthesis in which your body repairs the damage caused during training and rebuilds new muscle tissue.

The thing to take away here is that you NEED protein as soon after you finish lifting weights as possible, even if it is simply a whey protein shake mixed with water.

What Are The Benefits?

So, we’ve established that fasted weight training is not especially beneficial for anybody looking to pack muscle mass onto their frames, but we know that a little lean muscle mass is possible.

There are certainly easier ways to build more muscle mass, so why follow it in the first place?

Actually, there are lots of reasons.

Here are several benefits:

Burn More Fat

The primary reason why people choose to perform it and lift weights in a fasted state is so that they can burn fat.

It has been found to increase the rate in which we burn fat for fuel.

This is known as lipolysis.

You see, when you exercise, your body requires fuel in order for it to perform.

Just like a car needs gasoline to drive, your body needs the energy to exercise.

Its preferred source of energy is glucose, which it is able to easily obtain from carbs.

In a fasted state, glucose is unavailable, so what does the body do?

It panics!

It needs energy.

You’re clanging and banging in the gym, performing preacher curls, barbell squats, bench presses, upright rows, triceps kickbacks, and plenty more besides.

It needs the energy to get you through your workout, so it taps into the next available source – stored body fat.

Though studies are still ongoing, there is evidence to suggest that fasted exercise could result in you burning off 20% more calories than when training in a fed state.

This is why many bodybuilders will perform it with fasted cardio when dieting down for a contest.

Build Muscle

Though arguably not the easiest way to build muscle, you’ll be pleased to hear that weight training whilst in a fasted state will indeed help you to build more muscle mass.

This all depends on your post-workout “meal” of course.

Studies have found that fasted resistance training will facilitate a much greater anabolic response to your post-workout “meal” than when you train on a full stomach.

This results in a greater insulin spike which means that more protein and nutrients are transported into your muscle cells at a greater rate, where they can get to work on stimulating protein synthesis for optimal muscle growth and recovery.

What’s more, it may also help to promote increased production of anabolic hormones such as testosterone and growth hormone.

Increase Your VO2 Max

Put simply, your VO2 max is a term used to describe the body’s ability to utilize oxygen during exercise.

This is very important because the more oxygen you can utilize when training, the more energy you will have and the more productive your training sessions will become.

Not only will your workouts become more effective, but you’ll also be able to burn off more calories, and again, lose yet more fat.

Also, you can use our free TDEE calculator tool, which can be very helpful.

Burn Abdominal Fat

First off, you can’t spot reduce fat, so any nutritionist or personal trainer that tells you that they have a “special exercise” that will target belly fat and nothing else is talking complete nonsense.

With that said, there are things you can do to increase the rate in which you burn abdominal fat, and fasting is one of them.

It helps to increase blood flow to your abdomen.

This means more oxygenated blood can reach the abdomen and help enhance fat loss in this area.

The Takeaway:

So, before we draw proceedings to a close, let’s summarize what we’ve learned today.

We’ve established that it is possible to build muscle via fasted weight training, though there are certainly easier ways of going about it.

We’ve also established that it will help you to burn fat like there is no tomorrow.

Many bodybuilders follow a form of fasting during their contest prep when cutting down for a contest, and it’s easy to see why.

If you’re looking to burn fat whilst preserving the lean muscle you’ve already built, and maybe even gaining a little more, fasting is ideal.

Reda Elmardi

Reda Elmardi is a BJJ, fitness and bodybuilding fanatic. He's been writing about his experiences for over eight years and started his own publications on topics such as BJJ, Steroids, and Fitness.

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