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17 Diet Mistakes You Should Never Make, According to Nutritionists

Starting a diet isn't synonymous with depriving yourself from your favorite foods.

Picture this: You're planning to start a diet by paying more frequent visits to your local gym, adding more fresh foods to your diet, and cooking at home. But the second you set your mind to sticking to a new clean eating plan, the temptation of office doughnuts and happy hour specials just seem to strike at every corner. Sound familiar?

We've all been there. Starting a diet can be as daunting as keeping those pesky pounds on your waistline. That's why we've consulted top health and wellness experts about the most prevalent diet mistakes they've helped people like us overcome. Snoop through our exclusive report below to find out what you shouldn't be doing when dieting, and for more on how to eat healthy, you won't want to miss these 21 Best Healthy Cooking Hacks of All Time.

Thinking About Deprivation

Woman cravings

"One of the biggest diet mistakes I see with my patients is thinking about a diet as deprivation. Many of my patients come in and say that they want to cut out all sugar or cut out all fat, but by doing this you are restricting to a point that is most likely not sustainable." – Leah Kaufman, CDN, CDE, MS, RD

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Eliminating a Food Group


"Eliminating one food group … does not mean that you are going to automatically lose weight. You may, in fact, find yourself overeating these foods at some point. Finding a balance of your macronutrients is key! There is not one 'good' or 'bad' food that should be kept or eliminated from the diet. The role of a good diet is to find a balance of your plate and see which foods can help you most to achieve a healthy lifestyle change." – Leah Kaufman, CDN, CDE, MS, RD

"Being too restrictive and cutting out food groups leads to burnout early on when following a diet. This may discourage a person to follow the diet properly or eat healthier foods and exercise in general. Instead of cutting out food groups or being too restrictive, try following proper portion sizes. Moderation is key! [Eat] 5-6.5 ounces of lean protein at meals, 1.5-2 cups of fruits daily, 2.5-3 cups of vegetables (green leafy) daily, 6-8 ounces daily of grains, 3 cups fat-free or low-fat dairy daily. and 5-6 teaspoons oils daily."  Jim White, RD, ACSM

Setting Unrealistic Goals

Woman measuring waist

"I'm all for someone wanting to lose a significant amount of weight or striving to a run a marathon, but those huge goals can be unrealistic and overwhelming at first. It's better to set small goals that are actually achievable in the short run and work up to the larger goals. For example, if you want to lose 20 pounds, don't go on a crash diet that starves you and helps you drop pounds quick. Instead, change your behaviors slightly to lose 3-5 pounds per month. Those small goals are more manageable and will help you eventually achieve the larger goal." – Natalie Rizzo, MS, RD, NYC-based dietitian

Looking For a Quick Fix

Pill bottle

"I think the reason that extreme diets are so popular is because they help people drop pounds really quickly. But that way of eating just isn't sustainable. The first step to losing weight is realizing that it is going to require a lifelong change, rather than a quick fix. That's a big shift in mindset, but once you start thinking this way, it will help you in the long run. If losing weight was as easy as popping a pill or cutting out one food group, then no one would be overweight!" – Natalie Rizzo, MS, RD, NYC-based dietitian

Not Acknowledging How Good It Feels to Be Healthy

relaxed woman

"When I work with clients, I try to help them pay attention to how their weight and the foods they eat affect how they feel. Many people don't realize that they feel terrible after eating fried food or when they are at their heaviest weight. I think it's important for people to acknowledge that healthy food makes you feel good and losing weight makes you feel great. I have my clients keep a journal that tracks how food makes them feel. After they eat a large meal of fried or sugar-laden food, they mark down how they feel. They do the same thing after eating something full of fruits, veggies, lean protein and whole grains. Over time, it's easy for them to see that healthy food makes them feel better and they are more likely to choose that over the less healthy alternative." – Natalie Rizzo, MS, RD, NYC-based dietitian

Having Too Many 'Food Rules'

Woman with empty plate at wooden table, top view

"When it comes to dieting, we often give ourselves 'food rules' to follow (i.e., not eating after 8 p.m., no sugar, etc.) and then when we break the rules, because they are too restrictive, we get upset at ourselves, ditch the diet and overindulge. Don't focus on food rules. Instead, focus on being more mindful of your eating habits. Focus on including more healthier foods in your everyday life. And don't throw in the towel on your healthy eating habits when you indulge. Instead, enjoy it and choose a healthier option at your next meal. Eating healthy isn't an 'all-or-nothing' approach. It's a lifestyle." – Lauren Manganiello, MS, RD, CDN; registered dietitian and personal trainer in NYC

Being Impatient

depressed man

"Real weight loss takes time. Oftentimes, if we don't see progress in the first week or two, we get discouraged and quit. Set one long-term goal as well as smaller, short-term goals. Use the short-term goals as stepping stones to your long-term goal. And celebrate your short-term goals along the way. Looking back at your success and seeing progress is one of the biggest motivators for long-term success." – Lauren Manganiello, MS, RD, CDN; registered dietitian and personal trainer in NYC

If someone goes into a diet full-force thinking eating what is prescribed will drop a ton of weight in a short period of time, they have set themselves up for failure. Dropping weight in a healthy time frame takes time and dedication to diet and exercise. Try setting weekly goals for diet and exercise. Learn to properly track meals in MyFitnessPal to keep an accurate log of macro and weight goals. Remember [that] losing weight in a healthy manner takes time… Give it time!"  Jim White, RD, ACSM

Believing in Health Halos

Plain yogurt

"Greek yogurt is all the rage thanks to the powerful punch of protein it provides and the fact that it is loaded with bone-strengthening calcium. That being said, people often make the mistake of purchasing Greek yogurt with 'fruit on the bottom' and that is loaded with sugar. To reap the benefits of Greek yogurt, you are better off getting the plain variety and sweetening with a low glycemic fruit, like fresh blueberries. For some added sweetness, add a drizzle of an unrefined natural sweetener such as pure maple syrup—a little goes a long way!" – Chelsea Elkin, MS, RD, CDN

Compromising Flavor


"Diets often fail because of lack of flavor. Consider substituting parsley with watercress, to punch up the flavor of a dish, or use it in smoothies instead of spinach. In fact, watercress has ¼ the calories of kale while delivering just as many (if not more) nutrients." – Chelsea Elkin, MS, RD, CDN

Complicating Things in the Kitchen

Woman in kitchen

"Keep it simple! Don't doctor up simple foods so that the health benefits disappear! For example, Brussels sprouts can be a healthy side dish when sautéed with a little olive oil and spices. Preparing Brussels sprouts in this way allows the nutrition benefits to shine through … Brussels sprouts are a good source of the essential nutrient choline, which is important for memory and cognition and is a critical nutrient for pregnant women, for fetal development and proper child development. However, when loading veggies with caloric accompaniments (as often happens in restaurants), the health benefits can be masked, so be sure to prepare veggies at home whenever possible and don't complicate things in the kitchen!" – Chelsea Elkin, MS, RD, CDN

Shunning Fats


"A study conducted by California Walnuts found that 2 in 3 Americans believe that dietary fat is the enemy. One of the biggest mistakes I see is a fear of fat and particularly cutting out good fats. To the contrary, nuts like walnuts might help with satiety. Swap a handful of walnuts for chips or pretzels for a smart snack or toss toasted walnuts on salad greens or roasted vegetables for crunch, extra fiber, protein and better for you fats!" – Marisa Moore, MBA, RDN, LD

Aiming For Perfection


"All or nothing thinking. I find that when they are trying to eat better, many clients believe they have to be perfect. It's not necessary. I encourage clients to thrive in the grey area—that space where you are making healthy changes but not so restrictive that you no longer enjoy eating or physical activity. It's a process. Start with 1 or 2 changes a week (say increase water, eat at least 3 cups of vegetables daily, or exercising 150 minutes in a week). Build upon those to achieve a healthy lifestyle that you can maintain for a lifetime." – Marisa Moore, MBA, RDN, LD

Skipping Meals

Hungry woman

"Skipping meals may lead to quitting a diet quicker than anticipated. One may skip a meal thinking this will help lose weight in a faster time frame. This could lead to failure due to undereating and being hungry often forcing a person to come off the diet and eat to fulfill their hunger. Skipping meals means less energy and brain power to function throughout the day. Try meal prepping to ensure having adequate energy throughout the day (three meals and two snacks daily)." Jim White, RD, ACSM

Condering Cheat Meals as Free for Alls


"Many people believe that cheat meals do not count towards macro goals in the diet following. With this mindset, someone can easily gain back all their hard work if eating over 3,500 calories in a meal or day! Plan cheat meals accordingly and continue to track in MyFitnessPal. Consider foods with added benefits like dark chocolate with Greek yogurt and berries for antioxidants and protein."  Jim White, RD, ACSM

Not Counting Liquid Calories

Girl sipping soda

"With all the liquid beverages out on the market sometimes people forget to track the calories from beverages consumed throughout the day. Sodas, juices, coffee with creamer and sugar, alcohol are all examples of liquid calories. Be sure to read labels on beverages if they are available and continue to track in MyFitnessPal. Drink more water throughout the day."  Jim White, RD, ACSM

Forgetting Proper Preparation

Woman talking to doctor

"With all the current diet fads out in the media, it is important to do research on the diet you plan to follow by researching the diet on credible, scientifically based websites; or consult your MD/RD for more information. Your MD will let you know if the diet is appropriate for your current health state and the RD will help you set up a nutrition plan … [and] properly follow the diet in the safest way that works with your body."   Jim White, RD, ACSM

Not Focusing on Both Diet and Exercise

Man eating protein bar

"Eating a well-balanced diet while decreasing [calories] by 500–750 will promote weight loss… Exercise at moderate to high-intensity levels three to five per week for 30-60 minutes. [You] have to put in the work to see the results."  Jim White, RD, ACSM 

Speaking of exercise, don't miss out on these 8 Exercise Mistakes That Are Making You Gain Weight.

April Benshosan, MS
April is a born-and-raised Brooklynite who has a passion for all things health, wellness, and tastebud-related. Read more about April
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