Celebrity personal trainers share the 3 biggest mistakes people make when trying to get fit and lose fat — and what to do instead

• It can be tempting to follow extreme diets and workout regimes when trying to get fit and lose fat.
• But personal trainers who work with celebrities advised making gradual but sustainable changes instead.
• PTs whose clients include Ryan Reynolds said moderation and realistic goals lead to long-term success.

'Tis the season when people resolve to get fit, lose weight, and build muscle — only to quickly give up and make the same resolutions again a year later.

Four top personal trainers who work with both the general public and celebrities shared with Business Insider the biggest mistakes people make when trying to achieve their health goals.

They all feed into one central mistake: biting off more than you can chew.

Mistake 1: Trying quick fixes like fad diets

David Higgins, whose clients include Margot Robbie and Ryan Gosling, said that trying quick fixes and going to extremes will "often lead to burnout, injury, or a cycle of frustration because they don't address the root causes of poor movement, nutrition, or lifestyle habits."

That includes following fad diets with unsustainable restrictions or exercising too much.

Higgins advised going back to basics: "Focus on movement quality rather than quantity, prioritize consistency over intensity, and remember that small, sustainable changes compound over time.

"Start with foundational habits, like improving your posture, breathing correctly, and incorporating whole foods into your diet. These simple shifts set the stage for long-term success."

Mistake 2: Trying to out-train a poor diet

And remember, said Magnus Lygdbäck, whose clients include Alicia Vikander and Gal Gadot, you can't "out-train a poor diet."

"To lose weight you need to control your diet, eat fewer calories than you spend," he said.

Mistake 3: Setting unachievable goals then giving up when you inevitably fail

Luke Worthington, who has worked with Dakota Johnson and Naomi Campbell, said people also too often take an "all or nothing" approach to health and fitness. When they inevitably can't stick with their unrealistic new regime, they believe any slip-up has undone their good work and give up altogether, he added.

Instead, start with what's achievable for you, and don't copy a celebrity or athlete's plan, Worthington said. And it's OK if you can't fit in all your workouts one week or deviate from your nutrition goals sometimes.

"The most effective program is the one you actually follow, so setting realistic and sustainable goals is important," Worthington said.

"I find that the 'sweet spot' for most goals is to commit to three full body workouts a week, and then stick to it all year round.

"This is enough to make consistent progress, but also not too much where it becomes impossible to fit into a 'normal' life," he said. "If those workouts are balanced, working all major muscle groups through all planes of motion, and progressive — meaning you are able to increase your workload over time — then you will get results."

That's better than doing six workouts a week for six weeks but stopping because it's too much or you've been injured.

Get fit and lose fat sustainably by finding what you enjoy, need, and would like to improve

When approaching exercise, Lygdbäck recommends people think about three factors:

1. What you enjoy
2. What your body needs
3. What you'd like to master or improve

Then, try to find a way to tick each box every week. For Lygdbäck, that means a mixture of strength training, yoga and pilates, and Brazilian jiu-jitsu.

Don Saladino, whose clients include Blake Lively and Ryan Reynolds, called this approach the "moderation mindset," adding that taking time off to recharge and relax will prevent you from giving up after a few weeks. Consistency trumps intensity, he said.

Saladino gave the example of someone cutting down from drinking three days a week in 2024 to one in 2025.

"They just went from drinking 152 times throughout the year to 52," Saladino said. "Big improvement right there."