Lose 11 pounds in 2 days? The Myth of Fast Weight Loss

The Myth of Fast Weight Loss

I recently saw a Pinterest pin with the following claim: LOSE 11 POUNDS IN 2 DAYS! Ugh. I am so sick of seeing advertisements for scams that muddy the line between weight loss and fat loss. Do people actually fall for this stuff?

I think they do because I know I did in the past. Believe it or not, I understand the desperation to “get the weight off”. Almost two years ago I gained 20 pounds in less than two months. I’m a fitness trainer who makes her living off of helping people get healthy and lose weight. Despite the fact that adding 20 pounds to my frame didn’t make me overweight, there’s no denying that my job is tied to my appearance, so you can imagine my distress!

I was desperate to try anything that promised I’d lose the weight, and lose it fast. Keto, juice fasting, colon cleanses, liver detoxes…none of it worked (because I royally messed up my metabolism through dieting and extreme exercise...you can read more about that here).

What does the number on the scale even tell you about “weight loss”? Not much.

What does the number on the scale even tell you about “weight loss”? Not much.

The myth of fast weight loss: let’s define “weight”

Is it possible to lose 11 pounds in 2 days? Yes. In fact, if you don’t eat or drink anything and take the right dose of diuretics, you can probably lose 11 pounds in less than 24 hours.*

Here’s the thing: you didn’t ask where the 11-pound loss came from.

Let’s get something straight: when you want to “lose weight”, what you really mean is that you want to lose FAT. Am I right? If you lose 11 pounds of water, is that really the “weight loss” you were hoping for? Yes, it is a loss on the scale, but it’s not what most people are after…especially since water weight comes back less than 24 hours after the diet is done.

Today I want to show you how ridiculous these weight loss scams and diets are by actually doing the math. I want to show you that an 11-pound FAT loss in the span of two days…or even two weeks…is close to IMPOSSIBLE. So even if you hate math, stick with me because this is going to help you avoid wasting 48 miserable hours of your life only to lose what amounts to 11 pounds of WATER.

*I can’t believe I actually have to write this disclaimer…but please don’t be stupid. Using diuretics alone, or in combination with not eating or consuming fluids, can be deadly. Don’t do it.

It doesn’t require high math to figure out that fast weight loss is a myth. Let’s crunch some numbers!

It doesn’t require high math to figure out that fast weight loss is a myth. Let’s crunch some numbers!

The myth of fast weight loss: the numbers tell the truth

First we need to explore three scientifically accepted numbers related to metabolism, calories, and exercise. These numbers represent averages and are what we will use in our math equation to debunk the myth of fast weight loss.

The average woman (5’ 5” tall and 150 lbs.) burns about 2,000 calories per day. Depending on your height, muscular build, age, and activity level, you may burn more or less than this, but 2,000 is the generally accepted average.

It is also generally accepted that there are 3,500 calories in one pound of fat. To lose one pound of FAT, you must burn 3,500 calories. Or to gain one pound of fat you need to eat 3,500 calories in excess of what your body needs.

The average woman burns about 500 calories per hour while running at 6 miles per hour on a treadmill. Again, your calorie burn during exercise is dependent on many factors, but 500 to 600 calories per hour is a generally accepted average for running/jogging.

Got all that?

The myth of fast weight loss: Can I lose 11 pounds of FAT in 2 days?

If there are roughly 3,500 calories in one pound of fat, to lose 11 pounds of body fat you’d need to burn about 38,500 calories…and you’d need to do that in 48 hours to meet the diet claim.

Since we know the average woman burns about 2,000 calories per day, even if she does not eat anything for 48 hours, her total calorie deficit will only be 4,000. There are 3,500 calories in one pound of fat. That means she lost just a smidge over one pound of body fat by eating nothing for two days. Ugh.

Let me say that again for those in the back: after not eating for two days, she’s only lost one pound. Now she needs to make up the difference with exercise. To lose another 10 pounds of fat in 48 hours, she has to burn about 34,500 more calories. So how much exercise would she need to do?

Remember that our average woman needs to run for 60 minutes to burn about 500 calories.

How does the math work out?

To lose 11 pounds of FAT in two days, she has to eat nothing and she has run at 6 mph on a treadmill for nearly 70 hours.

Hmmm. I’m no math genius, but 70 hours is longer than 48. Someone didn’t do their math correctly…and it wasn’t me! Math aside, let’s also make note that anyone but an ultra-marathoner probably can’t run for 70 hours. I mean, would you even want to? Yuck. I’ll keep my 11 extra pounds of fat, thank you.

Fast weight loss comes down to bodily water fluctuations… not  true fat loss.

Fast weight loss comes down to bodily water fluctuations…not true fat loss.

The verdict: fast weight loss is a myth…if your goal is fat loss

It is not physically possible to lose 11 pounds of body fat in 2 days. Even ten days would be pushing the limits of what is possible. Fast weight loss almost always comes down to fluctuations in cellular water.

I think (I hope) this shows you how impossibly ridiculous — and maybe dangerous — it is to lose massive amounts of weight in short periods time. Sure, the scale may say you lost 11 pounds in 2 days…but it’s water, not fat! The next time you see this type of advertising, remember the math…and save yourself from a scam!

Let’s get a conversation going! What do you think about fast weight loss programs? Have you tried any? Leave a comment below and thanks for reading!

A note for “professionals” in the fitness industry: if you are a fitness professional telling women they can lose X number of pounds in X number of days…STOP. It’s shameful to prey on the pain of desperate women by promising results that are physically impossible. Fitness professionals need to be professional and stop this kind of false advertising. Quick weight loss is a scam at best, and harmful at worst. It ruins the reputation of fitness professionals and health coaches who are actually trying to do the right thing.


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Blog Author: Kelly Bailey, IIN certified holistic nutrition coach, and NPTI certified personal trainer

Learn more about the author here.