If you're no stranger to the struggles of trying to lose weight, the solution might be a few tweaks to your regimen. We enlisted the expertise of three nutritionists — Stephanie Clarke, RD, and Willow Jarosh, RD, of C&J Nutrition , as well as Mitzi Dulan, RD, author of The Pinterest Diet: How to Pin Your Way Thin  and CLIF Bar nutrition partner. Check out what they say are the biggest mistakes most people make when trying to slim down.
Not Planning Ahead
When hunger strikes and you're not prepared, that's when unhealthy decisions are made. Stephanie Clarke, RD, recommends planning ahead as much as possible. If you can, sit down and plan your meals and snacks out for the next week or two in advance, and then hit the grocery store with a list to stock up on everything you need from fruit to veggies to the containers you need to make a week of salads . It means that you'll have the food you want to eat on hand when you want to eat it, "which is the key for sticking to healthy eating for the long term."
Keeping It to Yourself
If it ever feels like the people closest to you are unknowingly sabotaging your healthy eating efforts, Willow Jarosh, RD, says to "consider whether you've shared your goals with them." Tell your family, friends, or co-workers that you're trying to lose weight, so instead of suggesting going out for ice cream after work, they'll invite you for a predinner workout. Having the support of everyone around you will make it much easier to stay on track.
Too Much Protein or Not Enough
While carb-free, high-protein diets are all the rage, and they do offer results, Willow says, "It's not sustainable or healthy for the long term, as you're missing out on vital nutrients" from fruits, veggies, beans, nuts, seeds, and whole grains. This variety of healthy foods "helps keep your gut bacteria happy, your digestive system regular, and keeps you feeling satisfied." On the contrary, Mitzi Dulan, RD, urges that not eating enough protein can also cause weight gain. She says, "Since protein helps you to stay satisfied, it is important to make sure you are eating it at every meal."
Compensating For Eating With Exercise
Whether you think that run earns you the right to inhale four slices of pizza, or you hit the gym just so you can eat whatever you want later, you're not only promoting an unhealthy relationship with food, but it can also lead to weight gain, warns Stephanie. A 30-minute run only burns about 250 calories , so if you devour 300 calories worth of dessert, it's no wonder you're not losing any weight and actually gaining instead. Use workouts to complement your healthy diet, not to make up for unhealthy eating habits.
Skipping Dinner For Cocktails
This is detrimental to weight loss for a number of reasons. Willow reminds us that "drinking on an empty stomach can lead to quicker intoxication," so even if you planned to just enjoy a few drinks, you'll end up losing the ability to make healthy choices and are more likely to order tons of food off the bar menu! Or even if the calories level out because you skipped dinner, you'll still have missed out on valuable nutrients, dropping your blood sugar levels. The result? Hunger coupled with the effects of alcohol will quickly nix that trip to the gym you planned. If you do enjoy your drinks with a meal, don't forget they add hundreds of calories without making you feel satisfied, warns Mitzi. The bottom line is to limit calories from beverages, and if you do go out for happy hour, enjoy one drink and spend the rest of the time sipping water.
Swearing Off Treats
Skipping out on your favorite foods like chocolate, french fries, wine, and ice cream can make a weight-loss diet seem pretty bleak. Since including these foods in small amounts on a regular basis can help prevent an urge to go overboard later, Stephanie and Willow encourage clients to have a "treat bank" of 150 to 200 calories each day. Or find healthier ways to indulge — these vegan chocolate mousse cups are only 100 calories !
Having Cheat Days
You stay on track all week, so you deserve a little reward, right? Not so fast. "One cheat day can undo all the weight-loss work you've put in during the week," warns Willow. If you devote an entire day to eating foods that don't push you toward your goal, "the only person you're cheating is yourself . . . and that's not good in the short term or long term." Instead, stick to the one small treat each day, and you shouldn't need a whole day to let loose.
Not Keeping Track
Monitoring your daily calorie intake is key when trying to lose weight, Mitzi says, and one of the most accurate ways to keep track is with a food journal. You can write it down with old-school pen and paper or use websites or apps, but make sure you keep track of every bite. "Research has shown this to be a major key to success for people who lose weight and keep it off," Mitzi explains.
Eating Diet Foods
Reduced-fat peanut butter may have fewer calories, but you'll find unhealthy ingredients and extra salt and sugar to make up for the flavor. Willow points out that a recent study showed that we might not feel as satisfied  with these low-everything diet foods and "that could cause us to end up eating more in the long run." All three nutritionists agree on choosing real food over "diet" foods and limiting the processed foods because it's healthier and more filling.