There's more to weight loss than looser clothes...
Fitness & Thinking Fridays highlights some of the other unexpected effects of getting in shape
There are a few things people expect when they start losing weight.
Feeling fitter. Looking leaner. Keeping up with the kids.
But what about the things they don’t expect?
This week, I want to talk about some of the weirder, less spoken-about side effects of fat loss – not the crash-diet clichés, but the real, physiological and emotional shifts that come from doing it properly, slowly, and sustainably.
Let’s start with a question I get surprisingly often:
“Why do I feel cold all the time?”
When you lose weight – especially if you go from overweight to a leaner, healthier body fat percentage – you’re losing insulation.
Going from overweight to a healthy BMI and feeling colder more often is actually really common, and there are several reasons for why:
Less body fat = less insulation (and fewer layers)
Fat acts as insulation. So when you lose a lot of it – especially around the arms, legs, and torso – you’re naturally going to feel more exposed to the cold. Add to that the fact that people often start wearing lighter, tighter clothes post-weight loss (partly for comfort, partly to enjoy the change), and you’re more physically and psychologically exposed to the elements, which is to say: there’s an inverse correlation between weight lost and need for floofy jumpers :D
Less food = less internal heat
When you're dieting, your body has less fuel to burn. One of the side effects of metabolism is the creation of heat – known as thermogenesis. Fewer calories going in means less heat being generated, especially if you’ve been in a deficit for a while.
Hormonal shifts
Losing fat lowers levels of leptin (a hormone released by fat cells). Low leptin tells the brain to conserve energy, which includes reducing heat production. You might also feel small changes in thyroid hormone activity, which can slow things down slightly and make you more sensitive to cold.
Nerd alert (but I think it’s fascinating): your mass to surface area ratio has changed
Think of your body like a campfire 🔥
Your muscle and fat are the logs – they produce heat.
Your skin is the air around the fire – where the heat escapes from.
When you were heavier, you had more logs and a bigger flame. More mass = more internal heat.
But your surface area – the skin and tissue where that heat escapes from – hasn’t shrunk as much as your mass.
So now, your body’s like a smaller fire heating the same size space.
You’re not broken – you’re just burning a little cooler than before.
That shift in thermoregulation isn’t a problem to solve – but it is one to be aware of. So if you’re layering up more than you used to? It might feel strange but it’s common and going into the warmer months might be exactly what the doctor ordered.
But the cold isn’t the only curveball you’ll field during fat loss…
Here are a few more unexpected (and very real) side effects of sustainable weight loss
Your sleep might change.
Some people sleep better as they lose weight, especially if they’ve reduced symptoms of sleep apnea or acid reflux. But in a calorie deficit, especially a prolonged one, others might sleep lighter – sometimes waking earlier than they want to due to some of the above mentioned hormonal changes.
Your social life might feel different.
Not worse – just different. You might say no to more meals out, or approach them differently. You might drink less, or move your Friday night from the pub to a walk or a gym session. This doesn’t mean you’re boring now – it means your priorities have shifted. It’s worth remembering that real friends won’t be weird about it.
Your palette might change.
I absolutely adore pick’n’mix and stuffed crust pizzas but when I get to the point of feeling lean and enjoying it, I’ll probably swap two pizzas a week and a bag of sweets for saltier and more satiating foods. I’ll also drink water a lot more than sugar free fizzy drinks (which I typically swear by as the weight initially comes off).
You might feel more emotions – and not always “good” ones.
People sometimes think getting leaner = getting happier. And sometimes, that’s true. But often, when people lose weight, they also lose distractions. If you used food or drink to cope (consciously or not), those habits aren’t there in the same way. That can leave space for emotions to rise – including sadness, frustration, loneliness. It doesn’t mean you’re doing something wrong. It just means you’ve made room for deeper work.
People might comment – and not always helpfully.
“Wow, you’ve lost so much weight!”
“You’re looking too slim now.”
“Oh, you don’t need to track your food anymore, do you?”
Everyone’s an expert when you change – even the people who weren’t paying attention before. You get to decide what feedback matters, and what’s just noise. Remember: you’re not responsible for how your changes make other people feel.
None of this is to say that fat loss is bad – it’s not. For many people, it’s transformative in ways far beyond appearance. But like any transformation, it comes with growing pains. The good news? They usually mean you’re doing something right.
So if you’re feeling the cold, or if the emotions are coming up as much as the abs – don’t panic.
You’re not broken. You’re just adjusting to a new version of you.
If you want help navigating the real side of weight loss – not just the stuff you see in before-and-after photos – reply to this newsletter with the word “COACH” and let’s work through it together.
What’s your experience of losing fat like, and has it changed over the years? Let me know!
Big shout to Beth for this week’s concept, and thank you to everyone who dropped DMs @coachjackmann in response to last week’s newsletter – it helps to know I’m not shouting into the void! Similarly, if you enjoy my work, liking, sharing and/or subscribing are small actions that can have big effects and all of them are appreciated.
Much love and I’ll see yas in the next one
Jack x