Trainer Shares Top 5 Mistakes That Prevent Weight Loss (and How to Fix Them!)

You try to be "good" so you eat a very restrictive diet, whether that means cutting out your favorite foods or severely restricting calories. It just increases cravings, and you end up binging. Then you feel bad and "punish yourself by severely restricting your calories yet again. And the cycle continues," Susan said.

Registered dietitian Leslie Langevin, MS, RD, CD, of Whole Health Nutrition, agrees and told POPSUGAR that the biggest weight-loss mistake is cutting out too much. Some people feel like they need to stop eating everything that's "bad" for weight loss, like candy, cookies, and fries, but that kind of diet is impossible to sustain.

Break the cycle by eating in moderation by following the 80/20 rule. Enjoy the foods you love in smaller portions, and have a moderate calorie deficit (not a huge one). This is a way of life you can live with and still see results.

While eating a healthy diet of whole foods — plenty of fruits and veggies, lean proteins, and healthy fats — is way more nutritious than living on pizza and fries, "eating clean is not calorie-free," Susan said. "Sometimes we often lose sight of the number of calories we are eating because the food is considered clean or healthy. Be mindful. Keep track of those calories just like any other calories." (We're looking at you, spoon in the peanut butter jar!)

Although it can seem strict, it's helpful to measure and track every lick, bite, and taste for a week or two to see just how many calories you're consuming. "That latte you had or the multiple handfuls of nuts you had during the course of the day? Those will add up quickly," Susan said. They could be the reason you're not in the calorie deficit you think you are.

While doing cardio does burn calories, it shouldn't be your main focus. Strength training workouts are necessary for building muscle, which Nicole Aurigemma, MS, who works in physiology at Women's Health and Exercise Lab at Penn State, says leads to weight loss.

"Focusing on strength training is going to build lean muscle that will change your body composition and keep you burning calories even at rest," Susan explained. Along with the four strength training sessions a week Jillian Michaels recommends, add some cardio you love, and go for high-intensity interval training. Like Susan said, "you may have the perfect one-two combination."

You didn't gain weight overnight, so don't expect your body to slim down overnight either. "It's the hardest part. In this world of instant gratification, we want results now, and we are prone to give up and move on to the next best 'thing' instead of seeing something through." Susan said. "There is no rush. Stay the course. You will win as long as you don't quit."

"If you are not making any progress with your current diet, a few tweaks here and there may be all you need," Susan said.