10 fat loss lessons a personal trainer learned throughout her 8-year fitness journey

When Mack was trying to lose fat, she fell into the trap of comparing herself to the women she saw in magazines, on TV, and on social media.

"Looking at social media and comparing myself to others or wanting to look like someone else led me to feeling unhappy," she told Insider.

"What I should have been doing is what I do now: Focusing on being my best version."

In her younger years, Mack didn't realize that the women she was looking at had often been photoshopped, filtered, or were manipulating their bodies using angles and lighting.

"So much of social media is a highlight reel with the best angles and lighting, and I was oblivious to that," she said.

If you're not sure where to start, it can be easy to think you should just do what you see other people doing, but this would be a mistake, Mack learned.

"You cannot copy what others are doing and expect the same results," she said.

"We are all so unique and we need unique plans that are tailored to our goals, our body types, and our individual preferences."

If you don't like running, don't go running. If you don't like weight lifting, don't lift weights, she advises.

"It's all about finding what works for you and what you actually enjoy doing and see yourself doing long-term," she said.

Looking for fat loss advice online can be overwhelming and confusing, and Mack stresses the importance of treading carefully, because people are often trying to make money from others' insecurities.

"There are always companies out there that are looking to make money from you. They will sell you quick fixes, detox teas, waist trainers, every type of fad diet and quick fix you can imagine — I know, because I've bought them before," she said.

Earlier in her fitness journey, Mack tried a "detox tea," but says she never would again.

She warns you should stick to evidence-based advice and scientific research from qualified individuals who aren't selling anything.

For years, Mack bounced from one restrictive diet to another, never sticking with anything and putting on more weight after each.

But, she says, whether you're trying to lose fat or build muscle, nailing your nutrition is essential.

"You cannot out-work a bad diet," she said. "If you're thinking you can go to the gym Monday to Friday and then at the weekend eat whatever you want, it doesn't work like that.

"If you want to lose fat, you need to understand that the only way to do so is with a calorie deficit."

Mack recommends using calorie-tracking app MyFitnessPal to learn how to fuel your body appropriately.

Many people have particular body parts they want to slim down, but you can't spot-reduce fat with a particular diet or way of working out, which is something Mack learned through trial and error.

"As women, fat often falls from our stomach, hips, and thighs last due to the way we are built," she said.

"If you want to lose fat from a particular body part, it comes down to consistency with nutrition and training.

"If you do 100 sit-ups every day, you might build a strong core, but you're not going to lose fat from your stomach unless your nutrition is on point."

Mack admits that like many people, she used to restrict herself massively with her diet, then do the polar opposite and overeat because she'd denied herself so much.

"Restriction was a big issue for me and I would have made so much more progress if I'd just been balanced," Mack said.

She points out that if you're really strict with yourself Monday to Friday but then eat loads at the weekend, you can easily undo the calorie deficit you've created, which is essential when trying to lose fat.

"You'll find yourself feeling really frustrated that you're maintaining or gaining weight week after week, and I know this feeling because I've been there before," Mack said.

"I wish someone had told me that calories count at the weekend even if you don't count them."

Mack says it's really important to define your reasons for wanting to get stronger, fitter, leaner, or whatever it might be.

"Understanding why you want to do something means you have that motivation when you don't feel like doing something," she said.

Mack recommends setting a goal that isn't just aesthetic-based, like wanting to have the energy to run around with your kids: "It needs to be something that really drives you," she said.

Mack suggests setting small, achievable goals to encourage the habits that will get you there.

"A goal without a plan is just a dream," she said.