What Is Set Point Theory? Why Diets Don’t Work Long-Term
29 July 2026 • Full Moon in Aquarius
The energy of authenticity and freedom.
So much of body image healing is about unlearning the belief that you have to change yourself in order to belong.
This Full Moon reminds us that true freedom isn't found in finally achieving the "perfect" body. It is found in releasing the need to earn your worth in the first place.
Body Peace begins the moment you stop asking your body to prove your value
On that note, I want to talk about something that completely changed the way I understand our bodies:
Set Point Theory.
Let me start with a question.
Why do we think healthy humans are all supposed to be the same size and shape?
If that were true, don't you think getting there would be a whole lot easier than it is?
As I touched on in my blog about BMI, healthy bodies come in many different shapes and sizes. Set Point Theory helps us understand one of the reasons why.
What is Set Point Theory?
One of the most widely accepted explanations for why diets don’t work is something called Set Point Theory.
The theory suggests that each of us has a genetically influenced weight range that our body naturally tries to maintain. Rather than there being one "ideal" weight for everyone, each body has a range where it functions best.
For some people that range is naturally smaller.
For others it is naturally larger.
Neither is wrong.
It is simply the way your body has been designed.
Different bodies are designed differently
I actually love using dogs as an example.
Think about different dog breeds:
No one expects a Labrador to look like a Greyhound.
A Greyhound is naturally lean, tall and built for speed.
A Labrador has an entirely different build, different strengths and a different healthy weight.
We instinctively understand that these dogs were never meant to look the same.
So why do we expect humans to?
Your body is not fighting you, it is protecting you
Our bodies are remarkably clever.
When we consistently eat more than we need, we have mechanisms that encourage us back towards our natural weight range.
But the opposite is true as well.
When we diet or eat in a calorie deficit for a prolonged period of time, our body doesn't simply continue losing weight forever.
Instead, it recognises that food has become scarce and begins trying to protect us.
Hunger increases.
Cravings become stronger.
Our metabolism adapts to conserve energy.
And our body becomes increasingly efficient at holding onto the food we do eat.
In other words, it starts doing everything it can to guide us back towards the weight range where it feels safest.
Why diets don’t work long-term
This is one of the biggest reasons long-term diets don’t work.
It isn't because you lack discipline.
It isn't because you've failed.
It's because your body is doing exactly what it was designed to do: protect you.
Your body is designed for survival, not society’s beauty standards
Now, this is a simplified explanation of Set Point Theory, and researchers continue to learn more about how it works. But what I want you to take away is this:
Your body is constantly working towards keeping you alive and functioning, not towards fitting society's beauty standards.
I often hear women say,
"My body is working against me."
But what if the opposite were true?
What if your body has actually been working incredibly hard to protect you all along?
Suddenly, the conversation changes.
Instead of asking,
"How do I force my body to change?"
We can begin asking,
"How do I start working with my body instead of against it?"
For me, that question is where Body Peace begins.
Your body will continue to change throughout life
Another important thing to remember is that our healthy weight range isn't necessarily fixed forever.
Our bodies naturally change throughout the different stages of life.
Teenagers have different needs than women in their thirties.
Pregnancy, breastfeeding, menopause, illness, stress and ageing can all influence where our bodies function best.
That isn't failure, it is biology.
Health was never a number on the scales
Your body was never designed to look like everybody else's.
It was designed to be your body.
Health isn't a clothing size.
Health isn't a number on the scales.
Health is a body that is functioning well.
One that is supported through adequate nutrition, joyful movement, restorative sleep, emotional wellbeing, meaningful relationships, connection and a regulated nervous system.
The more we understand how our bodies are designed to work, the easier it becomes to stop fighting them.
And I think that's one of the greatest gifts we can give ourselves.
Because Body Peace doesn't come from forcing your body to become someone else's.
It comes from learning to work with the body you have.
If you feel like you’d like support in moving towards this kind of relationship with your body, you can start with my body image meditation, this a first step back into connection with yourself.
Much love Marisa x
If you’d like deeper 1:1 support with your body image, you can explore coaching options here →
© 2026 Kokon Coaching | Created by Marisa Gundermann-Lunai.
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