Many dieting and lifestyle programs claim to help you “rev up your metabolism and lose the weight for good!” But that’s not how physiology works. Keep reading to learn how dieting slows your metabolism down, reduces your muscle mass, increases your set point weight. And makes it harder to lose weight.

Your body’s main goal is to protect you.

When you’re on a diet and restricting calories, your body makes the most of what it is given. It learns to live off of less calories than what it actually needs. But in order to adjust, it has to lower your metabolism. As well as use your fat stores for energy. This is why diets appear to work for a moment and you lose weight. But your body won’t keep doing that for long. Which is often why you hit a weight plateau.

After this initial period, your body will start breaking down your muscles to compensate for energy. Which further slows your metabolism down. When you start eating normally again for an extended period of time (think months; not weeks), it can start to increase your metabolism since your body now trusts you to feed it.

However, most people will start another diet before that can happen. This is when weight cycling (losing and gaining the same 10+ lbs) occurs. As well as an increase to your set point weight (your natural weight when honoring your body’s needs.) Making it even harder to lose weight in the future. All because your metabolism was compromised while dieting.

Proof Diets Cause Metabolism to Slow Down

Remember that extreme weight loss show ‘Biggest Loser’? In the first episode, they would be publicly shamed as they stepped on a scale and weighed in at 300+ lbs. By the season finale, the majority had lost 100s of pounds in 30 weeks. Media follow ups have revealed they all gained weight ranging from 50 lbs to all or more than they originally weighed. This has made this group perfect candidates for clinical trials on the effects of weight loss.

A 2016 study followed up with 14 former ‘Biggest Loser’ contestants 6 years after their season had ended. With the study’s objective “to measure long-term changes in resting metabolic rate (RMR) and body composition.” The study showed their metabolisms had slowed down by ±700 calories per day. And their muscle mass had dropped significantly as well (Fothergill et. al.)

This means their bodies perform LESS efficiently than before they lost the weight. And it had a lasting impact on their future RMR and body composition. I’d also like to note this is purely from a physiological standpoint of their body. Not one of mental health that considered their current relationship to food or the lasting impact on their body image.

Is Your Metabolism a Fire or a Single Flame?

How many diets have you done? Do you intentionally eat less food and reduce your portion sizes? Did you lose part of your appetite when you started intermittent fasting? All these things effect our metabolism.

Think about a campfire. When you want those big, vibrant flames you keep feeding it logs and sticks. When you want the fire to die out at the end of the night, you starve it. It naturally starts to lower down to just small flames licking up the wood it was previously given. Then glowing embers. And then smoke. Before putting itself out.

Your metabolism works like this in a lot of ways too. When you’re feeding it what it needs/wants, it’s most active, vibrant and efficient. When you reduce what you feed it, it’s still active but less vibrant. Reduce your food intake some more, and now it’s just doing the bare minimum—looking to existing sources for fuel. Stop fueling for long periods of time (fasting) and it struggles to keep up with your body’s needs. Further dipping into your muscle tissues.

The Truth About Dieting & Your Metabolism

This is why it’s maddening to see programs claim you will “rev up your metabolism and lose weight for good” with their products and meal plans. That’s just not how physiology works!

Instead, diets are a cycle where you initially lose weight. BUT you also slow down your metabolism. Eventually your body swoops in to protect you from restriction, so you fall “off plan.” And then you end up gaining back all the weight (oftentimes more) because your metabolism wasn’t prepared to eat normally again. But instead of continuing to meet your body’s needs and healing your metabolism, you freak out and start a new diet. And the cycle continues…

Diets don’t work long-term.

Dieting and under-eating cause harm to our metabolism, which makes it harder to lose and keep weight off. Start feeding yourself intuitively and heal your metabolism so you can feel your best! For more health tips and truth bombs about dieting, get your free copy of Diet-Free Living: A Practical Guide to Love Yourself Towards Healthy.

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