Look, I'm going to be straight with you.
I'm Matt, and as a personal trainer and sports massage therapist, I see the same patterns play out over and over again. People come to me frustrated, exhausted, and convinced their body just "doesn't work like everyone else's."
But here's the thing , it almost always does. The problem isn't your metabolism or your genetics. It's usually one (or more) of these seven mistakes that are quietly sabotaging your progress.
So let's go through them. And more importantly, let's talk about how to actually fix them.
Mistake #1: Living and Dying by the Scale
This one's massive. And I get it , the scale feels like the ultimate truth-teller. Number goes down? Good day. Number goes up? Spiral.
But your weight fluctuates constantly. Water retention, hormones, what you ate yesterday, whether you've been to the loo , all of it affects that number. I've seen clients drop a dress size while the scale barely moved. That's because they were losing fat and building muscle, which weighs more but takes up less space.
How I'd fix it: Stop weighing yourself every day. Once a week, same time, same conditions , that's plenty. But honestly? I'd rather you track how your clothes fit, how you feel, and how your strength is improving in your sessions. Those tell a much better story than a number on a screen.
Mistake #2: Eating Too Little (Yes, Really)
This might sound counterintuitive, but eating too little is just as problematic as eating too much.
When you slash your calories too aggressively, your body panics. Your metabolism slows down, your energy tanks, your workouts suffer, and eventually? You binge. It's not a willpower thing : it's biology.
Creating a calorie deficit is important (I've written more about that in Creating a Calorie Deficit That Doesn't Suck), but the goal is a sustainable deficit. Not starving yourself for three weeks and then inhaling an entire pizza.
How I'd fix it: Work out what you actually need to eat to fuel your body and your training : then reduce from there, sensibly. If you're working with a personal trainer, they can help you find that sweet spot. It's not about eating as little as possible. It's about eating smart.
Mistake #3: Skipping Strength Training
I see this all the time. Someone wants to lose weight, so they hammer the treadmill five days a week and avoid the weights section entirely.
Here's the problem: cardio alone burns fewer calories than you think. And worse : without strength training, you lose muscle as you lose weight. Less muscle means a slower metabolism, which makes it harder to keep the weight off long-term.
Strength training builds and maintains muscle, which keeps your metabolism ticking over nicely. Plus, it helps with injury prevention : something that's especially important if you're new to exercise or returning after a break.
How I'd fix it: Add two to three strength sessions per week. You don't need to spend hours in the gym. Even 45 minutes of focused work makes a huge difference. And if the gym feels intimidating, online personal training is a brilliant option : I can programme everything for you and you train wherever suits you.
Mistake #4: Falling for "Diet" Foods
Low-fat yoghurt. Sugar-free biscuits. "Skinny" ready meals.
These products are marketed as healthier options, but they're often loaded with sugar, sweeteners, and other additives to make up for the lack of fat. A 150g pot of low-fat yoghurt can have over 20 grams of sugar in it. That's not helping anyone.
How I'd fix it: Focus on whole foods. Protein, veg, healthy fats, complex carbs. The stuff that doesn't need a health claim on the packaging because it's obviously just… food. If you want to understand more about what actually matters when it comes to nutrition and training, have a read of Nutrition vs. Training: What Matters Most? : spoiler: it's both, but nutrition is probably doing more of the heavy lifting than you think.
Mistake #5: Not Drinking Enough Water
Boring? Yes. Important? Absolutely.
Dehydration slows your metabolism, messes with your energy levels, and can even make you think you're hungry when you're actually just thirsty. Most people don't drink anywhere near enough, especially when they're training.
How I'd fix it: Make it easy. Keep a water bottle with you. Have a glass with every meal. If you're training, drink before, during, and after. It's one of the simplest changes you can make : and it genuinely helps.
Mistake #6: Setting Unrealistic Goals
Thanks to social media and fad diets, a lot of people expect to drop two stone in a month. And when that doesn't happen, they assume they've failed and give up entirely.
But sustainable fat loss is slow. We're talking 0.5–1kg per week on average. That might not sound exciting, but it's the kind of progress that actually sticks. I've written about this properly in Sustainable Weight Loss: Why Slow and Steady Wins : it's genuinely worth a read if you've ever felt like you're not losing weight "fast enough."
How I'd fix it: Set process goals, not just outcome goals. Instead of "lose 10kg," try "train three times a week and hit my protein target." Focus on the behaviours, and the results follow.
Mistake #7: Guessing Your Calories (In and Out)
Here's a fun fact: studies show people underestimate how much they eat and overestimate how much they burn. Massively.
That "500-calorie" workout? Probably closer to 250. That "small" portion of pasta? Probably double what you think. Without tracking : at least initially : you have no idea whether you're actually in a deficit or not.
How I'd fix it: Track your food for a couple of weeks. Not forever : just long enough to understand what you're actually eating. Use an app like MyFitnessPal or Cronometer. It's eye-opening. And if you're working with a personal trainer, they can help you interpret the data and adjust your plan accordingly.
The Bigger Picture
Look, weight loss isn't complicated. But it's not always easy either : especially when you're trying to figure it all out on your own.
That's where having a personal trainer makes a real difference. Not because we have some secret formula, but because we can see the blind spots you can't. We can help you build a plan that actually fits your life, keep you accountable, and adjust things when progress stalls.
If you've been making one (or several) of these mistakes, don't beat yourself up. Everyone does at some point. The important thing is recognising it and making a change.
And if you want some help doing that? Whether it's in-person sessions or online personal training, I'd love to chat.
More in This Series
This post is part of a 7-part weight loss series. If you found it helpful, you might also like:
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