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Why (crash) diets don’t work

Updated: Nov 5, 2021

I’m so sick of articles and books pushing crazy and unhealthy weight-loss with crash / fad diets. So many smart people fall for them. And I wish they knew what they were getting themselves in to. I’m going to try to explain what happens to your body when you go on a crash diet.

When a person suddenly starts eating fewer calories, the body responds by lowering their basal metabolism (= rate at which they burn calories) to go in to fat-storing mode instead of fat-burning mode. The body will turn the calories they do consume mostly in to fat instead of energy.

Also, when that person starts to eat like they did before again (a crash diet can’t be kept up) their basal metabolism is lower, so they will gain weight more quickly than they would have before the crash diet. The number of calories they used to consume to keep a steady weight will now make them gain weight because the calories are burned more slowly.

Here’s a chart to help you understand this concept.

Certain diets also often leave out important nutrients which makes your struggling body even unhealthier. No matter what the latest fad diet says, all bodies need a certain amount of macronutrients (protein, carbohydrates and fat). If you drastically reduce or, even worse, completely cut out one of the three macronutrients, your body won’t be able to function properly. If you don’t eat enough carbs you’ll feel tired all the time. If you don’t eat enough fat, you’ll feel hungry all the time. Who wants that?

Another downside to crash dieting is that most of the weight loss is from water and muscle. The more muscles you have, the more calories you can burn. Also, it’s much harder to re-gain muscle than fat so when you re-gain the weight it will mostly be water and fat, leaving you weaker and with more fat than before you started the diet. This is also why it’s very important to add strength training to your exercise routine when trying to lose weight.

Following a (crash/fad) diet doesn’t sound very logical now, does it? So then why do so many people turn to them to lose weight? Probably because it seems quick and relatively easy and because not everyone knows exactly how their body works. I only started learning about the science behind our metabolism and how our body reacted to dieting when I took health coaching classes.

I believe the best way to lose weight is a combination of eating healthy food in moderation and exercise. Create your own diet and exercise routine. Find a healthy way of eating that you can stick with for the rest of your life and find exercise you enjoy doing regularly. It will take longer to see results, but the results will be permanent. And you won’t have damaged your body in the process. Consulting a doctor or health coach can help get you started ;).

When it comes to being healthy, there’s no such thing as a “quick fix”. If you want to achieve permanent results in a healthy way, you need to put in the time and effort, just like anything else in life. And the sooner you start, the sooner you’ll get to where you want to be!


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