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How Your Body Fights Against Weight Loss

Be warned - there is some not so great news about body weight in this post. If you haven’t heard, we’re going to explain how you’ve been fighting against your own physiology the whole time...

Last time, we talked about some misconceptions about body weight and health. Today, we’re going to talk about another misconception - calories in / calories out.

We normally think of body weight is a simple equation - eat more calories than you burn and you gain weight; burn more calories than you eat and you lose weight. The problem with that equation is that it implies diet and exercise are the only two things that influence body weight. In fact, body weight is also influenced by things like sleep, stress and medications, as well as environmental factors like socioeconomic status, food security, food environments… the list goes on (and so does the list of future blog topics!).

And not only are there external factors to consider, but the brain also controls body weight internally. Have you ever gone on a diet where you were starving ALL THE TIME? Or have you ever “cut out” a favourite food, only to wind up craving it even more than you did before? Or what about a workout plan where you were losing weight, and then suddenly you plateaued even though the workout was the same?

It turns out that your body doesn’t want you to lose weight, and it has some powerful mechanisms it can use to prevent this from happening.

Much like your body works to maintain a constant internal temperature, it also works to maintain a constant weight, or “set point”. And when you try to change your weight, your body can quickly undo your efforts by making you feel more hungry, or by making those chips seem even more appealing, or slowing down your metabolism so that you have to work out even harder to lose weight. This is the work of a complex system of hormones and neurotransmitters that you can’t turn off.

One common analogy is to think of a spring. Picture holding that spring at the top, and pulling down on it. The lower you want to pull it, the harder you’ll need to pull to keep moving it, and you can never let go, even if you get tired of all the effort. Because as soon as you do let go, it bounces right back up again, and the force of the bounce-back may even push it higher than it was to begin with.

Using this analogy, your set point is your highest sustained weight, which is like the top of the spring. The physiological changes that occur when you try to lose weight are like the tension in the spring - they fight against you all the time, and they don’t stop. And when you eventually get tired or frustrated with your diet and you give up, your weight bounces right back to where it was, and maybe even higher than it was. Stay at that weight long enough, and that becomes the new set point that your body will try to defend.

So why does this happen? The truth is that we don’t really know. We often think of this mechanism as a self-preservation adaptation that probably evolved over thousands of years when food was scarce, and famine was around every corner. In that world, weight loss was bad and could have life-threatening consequences. Unfortunately, our food environments have evolved much more quickly than humans do, and now in our modern society, we are stuck fighting against our own physiology when trying to manage weight.

Why This Matters

When we present this information to our patients in group classes, we refer to it as the “bad news” part of the talk. It’s bad news because we don’t have a full understanding of it, and we don’t have an easy fix for it. It’s the part that makes people rethink all of the countless days they’ve spent dieting, and it can be a bit defeating at first if they haven’t heard any of this before. The reality is that there is no secret diet that can get you around set point, no matter what anybody tells you. And even years after losing weight, you are still fighting against this mechanism.

But learning this information can also be validating for people because it helps them to know that their struggles haven’t just been about “effort” or “willpower”. And when they learn and understand this information, they can start to move beyond quick fix diets and unsustainable eating patterns. They can start to focus more on behavioural patterns and realistic goals. And they can be more forgiving of themselves when they inevitably have setbacks.

Because you’ve done short-term. You’ve done the “21 Day Challenge”. It doesn’t work because set point always takes you back. Successful weight management is a long-term game.

Our next posts will introduce some of the key behaviours and other factors that can help you be successful. Together, maybe we can figure out how hard to pull the spring so you won’t let go.

Until next time,






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