Your body has a weight it defends. Not the one you want, or the one you had five years ago. The one it believes is safe.
That’s your set point — a kind of metabolic memory that your body protects like its life depends on it. Because, in evolutionary terms, it does.
But the set point isn’t fixed in stone. The same biology that defends your current weight can also learn to defend a lower one — just not quickly. When you stay at a healthier weight for long enough, with steady energy, good sleep, and no famine signals, the hypothalamus gradually recalibrates. Appetite settles. Hunger hormones normalise. The “safe” zone shifts down.
You live in a Stone Age body trying to survive in a modern world. It’s wired to store energy and resist sudden change because, for most of human history, losing weight meant danger. But if you stop triggering those alarms, your biology can work with you, not against you.
That’s why roughly 95% of people who lose weight regain it within a year. Not because they failed. Because their body never got the time — or the conditions — to reset.
How the set point forms
When you gain weight, your body doesn’t just store more fat — it adapts to protect that new level. Your metabolism adjusts. Your brain rewires its sense of what “normal” energy reserves look like.
Over time, your hypothalamus — the brain’s control centre responsible for weight regulation — locks that number in like a thermostat setting. Drop too far below it, and your body sounds the alarm.
Metabolism slows. Hunger ramps up. You feel cold, tired, irritable, distracted by food. Every signal is designed to push you back up to safety.
It’s survival coding from a time when starvation was the biggest threat humans faced. The problem is, your body’s running the same hardware in a world that’s nothing like the one it evolved for. Modern life is like a software update that’s driven it nuts.
Diets backfire
When you force an energy deficit, your body doesn’t see your Instagram-friendly diet. It sees a potential famine.
So it adapts to conserve energy. People who lose significant weight often have metabolic rates 10–15% lower than expected for their size. They burn fewer calories at rest than someone who’s naturally that weight.
Meanwhile, hunger hormones surge. Satiety signals weaken as leptin (responsible for telling your brain there is enough energy onboard) gets blocked. You think about food constantly.
This is why “just eat less” never works long term. You’re not battling habits; you’re battling a survival system built to keep you alive.
And it’s very good at its job.
The rebound effect
Then comes the part everyone knows too well.
You finish the diet. You’re exhausted, hungry, and your metabolism is still suppressed. Suddenly food is everywhere again; fast, cheap, rewarding and tasty food.
The weight piles back on, usually faster than it came off. Worse, your body tends to regain more fat than muscle, because restoring energy reserves takes priority.
Within months, you’re heavier than when you started. Your set point hasn’t just stayed the same — it’s gone up. Your body “remembers” the famine and adds extra insurance against the next one.
That’s the yo-yo cycle. Physics meets biology, and biology wins. 🥵
Resetting your set point
The set point isn’t permanent. It can move, but not by force. You have to coax it down rather than pushing it hard.
That means:
Consistency over intensity.
Small, repeatable changes your body doesn’t interpret as a crisis.
Retraining, not extreme restriction.
Stabilise glucose, improve insulin sensitivity, rebalance hormones and you’ll provide the quiet signals that tell your brain it’s safe to let go.
Time.
Set points move slowly. It usually takes 6–12 months of stability before your body starts to accept a new normal.
Feedback, not guesswork.
The scale is only part of the story. What matters is how your glucose, hunger, energy, and sleep patterns are shifting. These are the cues your Stone Age body uses to decide if it’s still in danger.
The difference between losing weight and changing It
Losing weight is simple: eat less, move more, and numbers drop.
Changing your set point is biological: convince your body that this new state isn’t a threat.
You’re not fighting your metabolism but training it. Showing, over and over again, that this new rhythm of eating, sleeping, and moving is sustainable. That it can stop defending the old number.
That’s why crash diets fail, and why maintenance is harder than the loss itself. Crash diets didn’t changed the thermostat; they just turned the heat off for a while.
Pattern, not perfection
Your set point will move based on patterns, not one-off events. One takeaway doesn’t ruin progress. And one salad doesn’t sort it out.
What matters is the signal your body gets most of the time. Are your glucose levels mostly stable? Is insulin regularly dropping between meals? Are you sleeping enough to keep cortisol and hunger hormones in check?
If yes (most days, not necessarily all days), your set point will start to drift down. Quietly and gradually. Although fast weight loss is perfectly safe in many circumstances, the ‘maintenance period’ will take time.
The real goal
Your long term goal shouldn’t really be to weigh less. It’s to reach a weight your body’s willing to defend long term.
Once your set point moves, hunger normalises. Energy steadies. Maintenance stops feeling like deprivation and starts feeling like life again. It helps to think about altering your body composition to the right level rather than just losing weight.
Your body isn’t broken. It’s just ancient. It’s still trying to survive the Stone Age while living in the age of Deliveroo. Give it the right cues and the right fuel.
References
- Anderson JW et al., Am J Clin Nutr (2001): Long-term weight-loss maintenance in obesity management.
- Sumithran P et al., NEJM (2011): Long-term persistence of hormonal adaptations to weight loss.
- Fothergill E et al., Obesity (2016): Metabolic adaptation in The Biggest Loser participants.
- Leibel RL et al., Int J Obes (1995): Changes in energy expenditure resulting from altered body weight.
- Dulloo AG & Montani JP, Physiol Behav (2015): Pathways from dieting to weight regain.
- Hall KD, Lancet Diabetes Endocrinol (2022): Energy balance and body weight regulation revisited.
- Spiegel K et al., Ann Intern Med (2004): Sleep loss and hormonal changes influencing appetite.
