Gunnar Peterson Diet Advice© POPSUGAR Photography / Maria del Rio Gunnar Peterson Diet AdviceHaving regularly worked with scorching-hot celebrities like the Kardashians, trainer and wellness guru Gunnar Peterson knows a thing or two about living a balanced, healthy lifestyle. We had the chance to chat with him about the biggest mistake he sees people make in their diet when they’re trying to lose weight. His answer was pretty simple.”Probably the biggest mistake is that they eat too little too soon,” Gunnar told POPSUGAR. “They don’t pare down their calories, so they make drastic drops. And then, of course, your body’s going to respond to that, but then it’ll level off, and then frustration sets in.”

He said the focus is often about eating less, but he encourages us to see it about more than just quantity. Quality matters too. “Maybe it’s about eating better, eating at different times, combining your macros [protein, fat, and carbs] differently,” he explained. “All those things play into it, and they’re better served eating regular food than just diet food.” Rather than reaching for a packaged snack that promises to be worth only 200 calories, consider going for whole foods instead.

“Your body will adapt. It’s going to adapt to whatever you give it, and if you do it too quickly, it’ll adapt and then it’ll shut you out,” Gunnar said. That’s why he doesn’t recommend jumping on a diet trend too quickly. He says there’s a lot of “crazy” stuff out there, like skipping meals willy-nilly or cutting back significantly on certain food groups.

Instead of giving your body a shock, choose something that’s more sustainable. For example, make the decision to eat more whole foods and less sugar, and start cooking more. The more gradual changes you make in your diet, the more likely you are to see positive changes.