Top 5 Reasons Not To Crash Diet - Debunked

And why you should totally be doing it, according to science.

The widespread idiocy in the dieting industry is so pervasive it's almost depressing. Being the mere mortal that I am, I can only dispel one myth at a time - and today sights are set on crash dieting.

Crash dieting is defined as a drastic reduction in calorie intake (usually below 1,200) for at least 3 days in order to achieve rapid weight loss. There are a lot of opinions about crash dieting, most of which are substance-less. Here are the top 5 objections to crash dieting - debunked by science.

1. It's Better to Lose Weight Slowly than Rapidly.

Pixar / Via giphy.com

There is a belief that if you lose weight fast you will put it on even faster. The New England Journal of Medicine disagrees. Participants in their study classified as steady dieters became frustrated by slow progress and found it difficult to finish, less than half did actually.

Dietician Katrina Purcell, study leader, said: 'Achieving a weight loss target is more likely and drop-out lower if losing weight is done quickly.' Makes sense. I can't imagine why the diet industry would want you to stick to slow long-term weight loss plans. It's almost as if the sooner you reach your goals the less money they can make from you...

2. Crash Dieting Sends Your Body Into 'Starvation Mode'.

DreamWorks / Via giphy.com

Story goes that drastic calorie reduction sends your body into "starvation mode" causing your metabolism to slow and extra fat to be stored making you incapable of losing weight. This is a total myth that was disproven in the 40's by the famous Minnesota experiment where men were put on a 1570 calorie diet for a year, and they consistently lost weight the whole time.

Authority nutrition also discusses (destroys) 'starvation mode' in great detail.

Fat is a form of energy, you need to know that. Everyone needs to know that. When you consume excess food it is stored as fat, when you consume less the fat is converted into energy and used up. Eating less doesn't make your body store more. That's just not how it works, because science.

3. The Weight You Lose is Just Water and Muscle.

Warner Bros / Via giphy.com

This statement is a half truth used as an excuse to avoid attempting anything difficult. (No one ever said crash dieting was easy.) It is true that you will lose water weight when calorie restricting - because lowering calorie intake forces your body to turn to glycogen stores for more energy. Each gram of glycogen carries with it 3 grams of water, so as those stores are depleted, a lot of water leaves with it. Afterwards your body doesn't turn to muscle for more energy, it turns to fat - this is explained in point 4.

On the other hand, if you go water fasting for a month (yes, people do that) then you will lose some muscle mass. But that isn't what is being referred to as a crash diet, so not sure why I even mentioned it. Besides, most of us have enough fat stores to not need to worry about this 🙊

4. Crash Dieting Damages Your Metabolism, Slowing It Down Forever.

Universal / Via giphy.com

Slowing your metabolism down is touted as the apocalypse of future weight loss - lol. There is a lot we don't know about the human metabolism, but we do know that our metabolic rate (speed of calorie burn) increases and decreases as necessary - it's called adaptive thermogenesis. When you lose weight your body becomes more efficient and requires less calories to perform its daily functions, ala you burn less.

What you aren't being told is that while your normal metabolism may slow down, your body is capable of activating an alternate metabolic state known as ketosis. This is the process of breaking fat stores down into fatty acids that can be used as energy. It's all very science-y, but if you feel like nerding check out this article covering the basics of ketosis.

You aren't damaging your metabolism - if anything you are improving it by making it more adaptive. If you are still worried here are some ways to speed your metabolism back up.

5. Crash Dieting is Dangerous.

Now that the arguments are running thin it's time to pull out the last resort, "oh, well it's just dangerous". All this crash dieting talk is actually just negative language for what is really a fasting diet. Fasting diets are becoming widely accepted in the medical community. So anyone telling you otherwise isn't up on their science, or has some personal interest involved. I'll leave you to postulate where the crash dieting term came from.

The most recent research about fasting diets was published by USC. Their test group did 5 days per month on just 725 calories, for three months. Here are the results.

Valter Longo - USC / Via cell.com

Figure 6. Effects of a Human-Adapted FMD Regimen in a Pilot Clinical Trial
(A) Subjects were randomized to either the fasting mimicking diet (FMD) or a control group. Subjects in the FMD cohort consumed the FMD for 5 consecutive days every month for 3 months and returned to normal diet in between FMDs. Control subjects continued their normal diet. Measurements were performed prior to the diet (Baseline), immediately after the first FMD cycle (FMD), and during the recovery period after the third cycle (FMD-RF). Subjects in the control group were evaluated within the same time frame as the FMD-RF subjects (End).
(B) Glucose (n = 19).
(C) b-hydroxybutyrate (FMD n = 19, Control n = 18).
(D) IGF-1 (FMD n = 19, Control n = 18).
(E) IGFBP-I (FMD n = 19, Control n = 17).
(F) Body weight (n = 19).
(G and H) Trunk fat (FMD n = 18, Control n = 19) (G) and lean body mass (H) evaluated by dual energy X-ray absorptiometry.
(I) C-reactive protein (CRP; FMD n = 19, Control n = 18) levels of all subjects (left) and subjects in the average or high-risk group for heart disease (n = 8; right). (J) Percentage of lin CD184+CD45 mesenchymal stem/progenitor cells (MSPC) in the peripheral blood mono-nucleated cell population (FMD n = 16, Control n = 14).
All data are expressed as the mean ± SEM.

For those of you whose graph reading skills have gotten rusty, what you need to know is that this study brings to light the fact that calorie restriction is about so much more than just weight loss. For all the participants: 1) lean mass improved, meaning fat was lost and muscle was preserved, 2) risk of cancer and disease went down, 3) markers indicating longevity went up.

Lose Fat, Get Healthier, Live Longer - that's what "crash dieting" will do for you. SIGN ME UP.