July 22, 2019

Is Rapid Weight Loss Dangerous? What 8 Studies Say

by ironparadisefitness

Is Rapid Weight Loss The Fastest Way To Lose Muscle, Destroy Your Metabolism, And Damage Your Health? Here’s What 8 Studies Have To Say

Rather than shrink into the shadows, nutrition myths remain centre stage, hogging the limelight. The truth seemingly resigned to waiting in the wings for all eternity. Until now. Now is the time for the grandstanding to end, and for nutrition myths to die, so science can shine. And in this article, the spotlight is shining on rapid weight loss.

You might associate rapid weight loss with trends, fads, and BS supplements. Talk of low adherence, massive muscle loss, huge weight regain, slow metabolisms, and damage to your overall health, make rapid weight loss approaches seem a universally bad idea.

But that may not be the case. And while trends, fads, and BS supplements ARE a shit idea. There’s a way to approach rapid weight loss and be successful, while avoiding all these pitfalls.

Here’s the thing.

In this article, you’re going to discover the real truth about the Top 3 Rapid Weight Loss Myths, using 8 of the most credible research papers on the subject. These are the myths that are about to get busted:

  • Rapid weight loss diets are hard to stick to and result in less weight loss and more weight regain.
  • Muscle loss is a huge issue with rapid weight loss. A slower approach helps protect the gains.
  • Rapid weight loss approaches damage your metabolism.

So do you like the sound of a little myth busting?

Cool. Let’s do this.

Rapid Weight Loss Myth #1: Less Weight Loss & More Weight Regain

Rapid Weight Loss Iron Paradise Fitness

The Hypothesis:

Rapid weight loss diets are harder to maintain and result in less weight loss than a more gradual approach. The severe restriction causes over-consumption of calories following the dieting phase, and the weight piles back on.

The Truth:

Both rapid and slow weight loss approaches have merit. Of course, uncontrolled and reckless crash dieting is never a good approach. Trying to lose 10kg a week before you hit the beach, is leaving it a touch late. And in that scenario, you might be more likely to see your weight rebound faster than you can say, “well that diet was a bad idea.”

But this doesn’t mean losing weight rapidly is wrong. In fact, it might be the best thing for you.

Let’s back that assertion up with some evidence. A novel concept in the fitness industry, but it feels like you and I are nutritional trailblazers.

This study, separated subjects into 3 categories, FAST, MODERATE, and SLOW, relative to their degree of calorie restriction. Each group was monitored for weight loss and potential regain over 18 months.

So if the myth is to be believed, the groups using the slower approaches would experience greater adherence, greater weight loss, and minimal regain. Whereas the rapid weight loss group would theoretically abandon the diet after a week, exchanging it for Netflix Box Sets and eating their bodyweight in Hagen-Daas.

Here’s what actually happened:

  • Weight Loss: FAST= -13.5kg, MODERATE: = -8.9kg, SLOW = -5.1kg.
  • Weight Regain: No significant differences between either group.
  • No. Of Participants maintaining >10% weight loss after 12 months: FAST= 50.7%, MODERATE: = 35.6%, SLOW = 16.9%.

All evidence to show you can diet hard and get great results.

“That’s all well and good Simon. But I bet they weren’t jacked like me. What about the gains?”

Indeed, what about those precious gains? And that leads us on to our second rapid weight loss myth.


Rapid Weight Loss Myth #2: Muscle Loss “Won’t I Lose All My Gains?”

Rapid Weight Loss Iron Paradise Fitness

The Hypothesis:

Rapid weight loss results in significant muscle loss as a result of your body switching to protein for fuel in a severe calorie restriction.

The Truth:

You’ve been training hard in the gym. Sweating. Pushing. Pulling. And generally lifting heavy mass in multiple directions to sculpt muscle. So when it comes shedding body fat, you’re scared.

Scared a lack of calories will cause your body to cannibalise muscle. Eating away at your carefully crafted biceps and booty.

But dieting isn’t the muscle-feast you might think.

As long as you maintain an adequate level of resistance training and eat enough protein, you’re going to be just fine.

In fact, you can increase your deficit up to about 40% and you won’t lose muscle. Although, you’ll still have to train and keep protein at an adequate level.

“But what’s an adequate level of protein?”

Good question. If the goal is simply to preserve muscle, then your protein requirements aren’t that great. You certainly don’t need to live off of 10 protein shakes a day, and 4 chicken breasts with every meal.

In reality, your target just needs to be above 1 – 1.2g/kg. Research shows this is the threshold at which muscle mass starts to be affected.

Despite rapid weight loss appearing to be a Doomsday-like scenario for muscle, when you look at the evidence, it’s simply not the case. At worst, you’ll maintain the physique you’ve been sculpting all this time.

And if you look a little close at the data, you might even be able to make some gains in a deficit. So aim towards a higher protein intake (>2g/kg), keep hitting the gym, and you just might be able to book a ticket on the ‘Gain Train’. First stop Shredsville. Woo Woo!

But There’s A But…

Sadly, it’s not all good news. And the bros might have a point.

Rapid weight loss for those already lean could be a recipe for muscle mass loss. But this only kicks in where body fat levels are sub-10%. And that’s a genuine 10%. Not the 10% as measured by your bathroom scales. Even if they bluetooth data to an app, measure the contents of your large intestine, and touch your genitals as you get step off, they’re just not that accurate. Sorry, but it’s true.

“So. How do I measure my body fat accurately?”

Truth is, a DEXA scan is one of the only ways you’re really going to get a true understanding of body fat. But they’re expensive and not something you’ll do with any regularity. In practical terms, if you’re sub-10%, you’re already pretty damn lean and you’ll know it.


Rapid Weight Loss Myth #3: Metabolic Damage “Won’t It Slow My Metabolism Down?”

Rapid Weight Loss Iron Paradise Fitness

The Hypothesis:

Rapid weight loss and skipping meals causes your body to go into ‘Starvation Mode’. Your body thinks you are starving, so when you next eat, more fat will be stored as part of this protective mechanism. Eventually, the body’s metabolism will slow down to the point fat loss stops, regardless of how low calories are.

The Truth:

The truth on this one is pretty clear. In the real world, ‘Starvation Mode’ doesn’t exist.

Ask a Prisoner Of War from WWII if their body reached Starvation Mode and retained body fat. And ask the same question to a person suffering with anorexia.

If you don’t eat, you will starve, lose weight, and eventually die if you choose to push things that far. It’s that simple.

Take this guy for example, who voluntarily went on a medically supervised fast for 382 straight days (a World Record). You might be desperate to lose weight, but I’ll assume not that desperate. Although, as a point of principle, let’s see what happened to him.

  • Starting Bodyweight: 456 lbs
  • Final Bodyweight: 180 lbs
  • Bodyweight 5 Years After Fasting: 196 lbs

So, in a little over a year, he dropped 60% of his bodyweight at a rate of 0.72 lbs per day (that’s 0.33kg for my European brethren). Testament to the fact if you want to push weight loss hard, you can. Although, please don’t attempt something like this. Remember, it was supervised in a hospital. And I don’t imagine he held on to his gains either.

Are You Saying My Metabolism Won’t Slow Down At All?

Your metabolism WILL slow down. That’s a fact. But it’s nothing to do with rapid weight loss.

If you lose weight, your Basal Metabolic Rate goes down. Which is simply a result of you occupying less pace on the Earth and having less gravitational pull. So it’s perfectly natural. Frankly, if you didn’t see a reduction, there’s something not quite right.

Think about it this way. Jabba The Hut is obese. I’m not body-shaming him, it’s fact. And his BMR will be reflective of that high weight.

But let’s say you put him on a diet, rapid or otherwise (you decide). He loses a ton of weight. And now he’s more Jabba The Garden Shed. Well, that means our favourite Galactic Gangster’s metabolism will be lower than when he started. He’s not damaged or unhealthy. It’s part of the process.

A Word On Metabolic Adaptation

Phrases such as ‘Metabolic Damage’ get thrown frequently. Often, in the same breath as rapid weight loss.

“Smash your calories through the floor and you’ll fuck up your metabolism forever.” Or words to that effect, right.

But there’s not really any “damage” taking place. It’s more a Metabolic Adaptation.

This may start to occur when you lose more than 10% of your original body weight. But what does this all mean in practical terms?

Well, it essentially means that your body gets used to the lower amount of calories you’re giving it, and becomes more efficient with energy.

For example, the body will down regulate NENAT (Non-Exercise Non-Activity Thermogenesis – think fidgeting, etc) without you realising. So you’ll fidget and move less than normal. There may also be an impact on NEAT (Non-Exercise Activity Thermogenesis – think walking etc). If you’re not monitoring and consciously maintaining step count, left to your own devises, you might move less through generally lethargy, Basically, you’re balls (or ovaries) deep into your diet and you can’t be fucked to move.

And this all happens, EVEN IF you retain those hard earned gains.

Here’s How Much Metabolic Adaptation Might Affect Calories Out

Back in 1944, rules and ethics of human research were a little lax, shall we say. And that meant a study, later referred to as The Minnesota Starvation Experiment was conducted to test the physical and psychological effects of starvation and the problems associated with refeeding civilians, impacted by WWII. Placed on semi-starvation diets, participants experienced a 40% reduction in energy expenditure. 25% of which was due to weight loss. And the other 15%, a result of metabolic adaptations. Therefore, showing the direct and indirect impact of weight loss on your metabolism.

What About Reverse Dieting?

Reverse Dieting is largely unnecessary. There’s no magical metabolic healing properties at work. Avoiding a post-diet binge and getting back to newly estimated maintenance calories is the unified consensus view on the best approach. Reverse Dieting protocols lasting for as long as you dieting are not necessary. Essentially, you are staying in a calorie deficit, although reducing that deficit over time.


The Bottom Line On Rapid Weight Loss Myths

Rapid weight loss is a perfectly acceptable approach, in the right circumstances, for the right person. Myths of less weight loss, huge muscle loss, and damaged metabolism are not supported by the research.

Now, I’m not saying you should definitely try a rapid weight loss approach. Because, for you, it may not be the right way to go. But, it would be wrong to dismiss it altogether. The research shows clear benefits for certain people.

So how do you know if a rapid weight loss approach is right for you?

Here’s some considerations of when a rapid weight loss approach might not be right for you, if…

  • you’ve tried low calorie diets in the past and struggled to stick to them.
  • you have a poor relationship with food.
  • you have (or have had) an eating disorder (or disordered eating tendencies).
  • you’re already very lean and you want to retain your muscle.
  • you have a long history of dieting

What are the benefits of rapid weight loss IS for me?

If you’re in the clear and decide a rapid weight loss approach might be just what you need, the benefits are quite enticing:

  • Early results may increase your motivation and get you excited about losing more weight
  • You spend less time balls deep in a diet. Winner. Winner. Maintenance calorie dinner.
  • Dieting is over sooner, so you can get back to maintenance and benefit from improved training and recovery.
  • You can also take more frequent diet breaks during the process (if you want).

Like with any dieting method, selecting the right one is very much an individual decision. Rapid weight loss might be right for you. It might not. But the important thing to remember is that the research supports it as an evidence-based option. Because while it may not be right for you. It could be right for a lot of people.

Top Tips For Making A Rapid Weight Loss Diet A Success

It’s easy to think a rapid weight loss approach is simply a case of smashing calories through the floor and grinding your way through each and every day..

But there’s a right and a wrong way to do it. Here’s some top tips, so you get it right.

  • Focus on less calorie-dense foods. Keep your diet simple and abundant in unrefined foods.
  • Maximise the amount of home cooked meal to make controlling calories easier.
  • Take positive steps to manage potential cravings, including:
    • Remove calorie dense foods from your food environment.
    • Maximise sleep
    • Exercise regularly
    • Reduce Stress

Make these the foundation of a rapid weight loss diet and you’ve got every chance of it being a rapid success.


Your Next Step To Mastering Nutrition And Shaping A Leaner, Healthier, Stronger Body

iron paradise fitness

Here’s what to do next to get on the fast track to a leaner, healthier, stronger body. Simply click the link below and I’ll send you my Lean Life Kickstarter Pack. In it you’ll find a free 4 week beginner’s training programme (complete with exercise videos and a workout tracker), a guide on calculating your calories, plus so much more.

If you want it, grab it here.

But for now, all I’ll say is… Keep living the Lean Life and I’ll see you soon.


fat loss, fiber, fibre, nutrition, weight loss

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