13 Major Downsides of Crash Diets: Why They're Harmful

13 Major Downsides of Crash Diets: Why They're Harmful
December 30, 2023
Viking Beast

Allow me to kick this article off with a small background story.

I’ve been working out for a little over 6 years now at the time of writing.

I started just before I turned 17 at a bodyweight of 63 kilograms (139lb.) with a height of 187cm (6ft1).

Over the years I’ve gained and lost weight more times than I can count, and probably tried every pace of dieting you can do. However, there was one time that I took weight loss to the extremes, and that’s why I’m writing this article today.

I went from 99kg (I gained a little too much weight that’s for sure) to about 76 kg in 6 months and got pretty lean.

I worked out for about 2-3 hours a day and ate between 1500-1700 calories a day (during normal times I eat over twice this amount).

You can easily classify what I’ve done as an extreme weight loss or crash diet.

If you’re currently considering trying something like this for yourself, then you can read about my experience first. Perhaps it will make you reconsider, or at least you’ll know what side effects to expect.

Here are 13 ways crash dieting may ruin your life. For each of the following topics, I write out of experience.

Except for the last one, which is a warning for the female audience. Let’s go.

Extreme weight loss slows down your Metabolism

Six month weight loss transformation
My metabolism crashed like a rocket.

While I was dieting I was determined to do whatever it takes. At that time I didn’t think about life after the diet, which was a huge mistake.

If you’re dieting too fast, your body will just “slow down” to preserve its energy. Your body wants to survive, which might be annoying while dieting, but sure is a good thing in general.

If your body was burning 3000 calories at rest before the diet, expect this number to drop immensely afterward.

Extreme dieting or crash dieting will mean you’ll be able to eat way less food after the diet ends. That is if you want to maintain that new weight.

Sob story: I calculated the calories of my daily pancakes wrong by 500 calories, and gained a lot of weight (fat) back in a couple of weeks before I noticed the problem.

You lose strength & muscle mass

140kg benchpress
I was a (little chubby though) monster before that diet, or at least it felt like that.

I finally achieved my goal of 3 plates on the bench press, which is 140kg (315lb.), but before I could even fully wrap my brain around my achievement, it was gone… And not just gone.

It was so far away, it was basically like I had to start all over again. I think I was doing 80kg for a couple of reps at the end of my diet, which is absurd.

The weight I lost was not just fat either.

I was weight training and watching my sleep schedule, and protein intake. I did everything I could to preserve muscle and still became twice as small (muscle-wise).

It was extremely painful to see so much progress leave this planet.

Losing weight too fast can cost you a lot of progress.

Tip: I’ve learned that with a slow, and healthy diet, it’s possible to not only maintain your strength but get stronger too.

Extreme weight loss crashes your hormones


Writing this still gives me shivers, about what a stooped idea that weight loss strategy was.

I’ll be completely transparent here, so you know in numbers what can happen. I get my blood tested regularly, just because I like to measure things such as my testosterone levels.

Before I started the diet my testosterone was mid-600s. After the diet, it dropped to the low-200s. That’s the very low end of the “healthy range”, but for a 20-year-old that does everything to maximize his hormones, that’s life-ruining low.

I’ve since returned to levels in the 500 range, but it’s still not where it once was.

Good to know: Not only testosterone gets affected. Other hormones will suffer as well.

Extreme weight loss sounds good, but it's not worth it at the expense of your body.

The big takeaway: Never ruin your hormone levels, you can’t even imagine how important those hormones are until it’s too late. Trust me on this one. This is one way a crash diet can ruin your life.

A crash diet kills your libido

Netflix on a tv screen with red lights
Do you like Netflix & Chill? Well, now you only like Netflix.

It’s a painful experience when you’re a young guy, with an awesome (and pretty) girlfriend, and you just physically don’t feel like doing anything anymore.

I can’t frame it any other way, it’s just ridiculously awful.

Oh, and another thing. It’s not fun when your morning wood, doesn’t say good morning anymore.

Yes, this happens too.

Waking up is suddenly not that hard anymore. One advantage though, it’s easier to pee in the morning.

Don't let a crash diet ruin your sex life.

Note: Last three weeks of the diet my girlfriend was in America (luckily).

Energy levels drop to none

Quote "make today tolerable"
Do you like to go on adventures?

Well, the only adventure you’ll want to do is walking to the bathroom. And even that’s too much.

I did my daily workouts, and that was the only thing I did. I could do this, because I had summer vacation (3 months off school), but it ruined my summer.

As the diet progressed my energy levels kept dropping. In the end, I could barely get myself to physically stand up, and in no way or shape could I go to any event with friends.

An absolute waste of summer, such a shame. But hey, we learn from experience. Extreme weight loss will cause your energy levels to plummet.

Big tip: Learn from my experience, instead of trying to crash diet yourself.

Drive for life goals

Hustle on a coffee mok
Do you have some big plans for the future?

Or perhaps like to “hustle” or “grind”?

Well, if you don’t feed your body enough, then your body doesn’t give a single lollipop about your goals.

I can guarantee that no matter how driven you are, you will be achieving your plans at 2% speed.

In terms of my physique, my diet, and workouts, I had complete tunnel vision.

All other things I wanted in life were put on hold. I completely lost my drive for anything else I wanted to achieve in life.

Extreme weight loss can cause a loss in interest in other areas of life.

Warning: You’re absolutely not productive anymore.

Crash diets can cause black-outs

Blacked out light
I felt like I was living in a constant WWE match.

At random times during the day, it would just go pitch black before my eyes completely.

It’s normal (I think) to experience this sometimes if you stand up too fast. But during this diet, it would just happen constantly out of nowhere.

Extreme diets or crash dieting causes your blood sugar levels to drop immensely, which causes those short-term blackouts. One time I fell in the bathtub, it wasn’t pretty.

Lights out: it can make your lights go out, be mindful of this.

Crash your immune system

Bacteria will love you even more.

The bad news is your body won’t care about it, which means you can kiss goodbye to your natural defense system.

During my extreme diet, I was way more susceptible to illnesses and other small diseases. It was like my body was constantly battling things, and I always felt sub-optimal.

Not something I can recommend.

Note: You’ll get sick a lot more often, which is annoying.

Your brain doesn’t function well

Quote "feed your head"
I’m pretty good with numbers, except now I was not.

During my crash diet, my brain couldn't perceive information. It was like I couldn’t remember the most basic things, and I would constantly mess things up.

I’m naturally clumsy, which doesn’t help. I would straight up bump into anything. This in combination with blacking out regularly, made for a really dangerous combo package.

It’s also kind of scary when your brain doesn’t function as it used to before, especially if you’re pretty young.

Extra warning: Your brain is important, crash dieting will not treat it well.

Crash your relationships with other people

Quote "be kind"
Do you like to be around other people?

I would say I enjoy the company of other people sometimes. But when I was deep into the diet, I didn’t just enjoy people.

I could simply not stand most of the daily human interactions. Sometimes sound itself would be too much to bear.

Anything would irritate me as well. I was so quickly irritated, that I was just a pain in the ass to live with. I don’t know your answer to my question, but other people will sure as a wonderland, not like you.

As the commercial goes, you’re not you when you’re hungry. And they’re right.

Extreme weight loss will cause your relationships to suffer badly.

Important note: Other people will not enjoy you, and you’ll not enjoy them.

You miss out on life

Best summer ever.
So important, but so often forgotten.

When you’re crashing dieting, it’s simply not possible to participate normally in life’s events. You can’t go out with friends like you normally did, nor do you even want to go for that matter.

Everything becomes a battle, a struggle, something you have to overcome. I’m not talking about crazy things here, but simply going to visit someone can trigger these feelings.

Like I previously said, I did it in the summer, which is the time to have fun. I had tunnel-vision, that’s it. I don’t regret it, because I learned about myself a lot.

But I don’t recommend it.

Life advice: You have a life to live, so don’t do things that prohibit you from living it.

Bonus for girls: your menstruation cycle stops

Lady boss tag
When you take dieting to the extremes as a girl, your body won’t be able to function well.

To preserve energy, it will shut down anything related to reproduction, because at those times it’s simply not necessary to survive. This means your menstrual cycle will just stop completely.

Extreme dieting to this point is very bad for your health and is most certainly something you should try to avoid at all costs.

Tip for the badass girls: Don’t let something like a diet ruin your body, and menstrual cycle.

Final words

While I like pushing my body and mind to the extremes, crash dieting too hard was one of the most stooped things I’ve ever done.

It took my hormones, and body in general, over a year to recover from it. I’m writing this article to let other people learn from the mistakes I’ve made.

If you’re considering following a crash diet, you at least now know the side effects that may or may not happen to you.

What negative side effects have you experienced from dieting?