Can You Lose Muscle in One Day? (According to Science!)

We know it can take a really long time to actually build muscle- like, a LONG time.

So, people don’t want to lose muscle. We all know that skipping workouts, eating a poor diet, and more can cause muscle loss.

But, can you lose muscle in one day? No, you can’t really lose muscle in one day unless you literally ate nothing for 24 hours and worked out really hard. But, for the most part- it takes 3 weeks for your muscle to start breaking down if you haven’t eaten or worked out, according to a scientific study.

Let’s look at some of the science behind this.

Can You Lose Muscle in One Day?
Can You Lose Muscle in One Day?

#1 – How Long Does It Take For Us To Lose Muscle?

There are many internet gurus that will claim you can lose muscle in just a few hours- this really isn’t the case.

For the most part, it will take WEEKS of not working out and eating poorly to lose muscle.

The only exception is if you were literally STARVING- ie: eating NOTHING for days on end. In that case, you’ll probably start losing muscle rapidly.

But, starving is a huge line from just eating less. Even eating less than you usually do will usually just cause fat loss, not muscle loss.

Only Small Amount of Muscle is Lost After Weeks, It Takes MONTHS For Serious Muscle Loss

Yes, it will take a few good weeks to start losing muscle, but it’s not actually a lot of muscle you’ll lose.

It really takes MONTHS for serious muscle loss.

We saw this a lot during COVID- when all of the gyms got shut down. Many people didn’t have access to gyms for months- and strangely didn’t even lose that much muscle.

With Proper Dieting – You Can Lose Very Little Muscle After Months

As I was saying, when all of the lockdowns happened and literally like nobody was able to get to a gym for months- people saw that we weren’t actually losing much muscle at all.

Now, this takes a proper diet. Most people stayed eating their normal protein levels, and found out that even after months of not working out- little amounts of muscle were lost.

Sure, there was some- but it’s certainly not as catastrophic as those online internet fitness gurus might make you think.

I personally thought I was going to lose almost a year of hard work since I hadn’t worked out in nearly 3 months, but truthfully- I just lost a ton of fat and barely lost any strength.

Sure, I did lose some strength and muscle- that’s a given. But, it took me like 4 weeks to get that all back.

Truthfully, with proper dieting and some at home workouts, you won’t lose all of your gains over even a few months- you’ll lose some noticeable muscle, but it’s not as much as you may think.

#2 – So, Really, One Day Won’t Mean Anything

When we look at the facts that you can go weeks with basically zero muscle loss, and months with little muscle loss- one day won’t really mean anything.

So, you can rest assured that if you skipped a workout or had a bad day- it’s all okay.

Our bodies are really resilient and strong. And they’re good at keeping muscle- don’t listen to what the internet fitness gurus say.

#3 – What Could Cause Muscle Loss in One Day?

Now, it’s very difficult to cause any muscle loss in one day, but there are a few days to do it.

  • Starving, like literally eating NOTHING for 24 hours.
    • And I emphasize NOTHING. If you just missed a meal or two and had some snacks, you’re fine. I’m talking about the person who hasn’t eaten ANYTHING for 24 hours, you might see some muscle loss then.
  • Working out non-stop all day and not eating any protein.
    • This is sometimes seen in hikers, but even then it’s rare. This usually happens when people work at a job like construction and work really hard all day and don’t eat to fix it. You’ll usually feel very, very sore the next day- and the only thing that will fix it is protein. You’ll learn really quick on the job to eat right.
  • Not sleeping, eating, drinking, and constantly exercising.
    • For some of you fellow first responders, that might sound like another Tuesday for us. But, if you do end up on one of those weird party nights where you’ve been up for 24 hours and haven’t eaten anything and you’ve just been dancing non-stop- you might find yourself losing a bit of muscle. But, this is very rare.

#4 – If You’re Really Worried, Just Do Some At Home Workouts

If you’re really worried about muscle loss, just do some at home workouts.

  • A study titled, Exercise dosing to retain resistance training adaptations in young and older adults, found that basically if you did 1/9th of the volume of your normal workouts, you wouldn’t lose basically any muscle for around 33 weeks, which is almost a full year. That means if you normally went in the gym and did a full 2 hour workout, you could do a quick 15 minute workout at home and you wouldn’t even lose muscle.

With that in mind, if you’re truly worried- just do some at home stuff and it will work.

I recommend Convict Conditioning, it’s a pretty solid at home workout program designed for building muscle in a prison cell. (and who knows, depending on who you are- it might help you when you’re locked up! hopefully not, right?)

#5 – Frequently Asked Questions

How Fast Can You Lose Muscle From Not Eating?

You can lose muscle from not eating within a day. If you ate literally NOTHING for 24 hours, your body would be breaking down muscle. However, skipping a meal and starving are two different things- we’re talking about full-on starvation here.

If you’re fasting for a long time, you should take some BCAAs – most religious practices allow BCAAs to be eaten during a fast as they aren’t food. They’re just powdered mini amino acids that discourage your body from breaking down muscle- they are not food in any way.

What Causes Rapid Muscle Loss?

Rapid muscle loss is caused by eating virtually nothing, eating very little protein, engaging in very intense physical activity without proper nutrition, and some medical conditions cause it.

Most rapid muscle loss occurs during starvation.

Will I Lose Muscle If I Fast For 3 Days?

No, you probably won’t lose any significant amount of muscle if you fast for 3 days. If you are concerned, try taking BCAAs- most religious centers allow BCAAs to be taken as they aren’t food. They are just a consumable powder/pill you take that ‘discourages’ your body from breaking down muscle.

#6 – Conclusion of Can You Lose Muscle in One Day?

So, no- you can not really lose muscle in one day unless something seriously wrong happened medically.

If you’re just taking a day off the gym or had a rough day- don’t worry about it. You’re fine.

See you in the gym! 🙂

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