The #1 Mistake People Make When Starting a New Diet, According to a Dietitian

Some changes can do more harm than good.

an illustration of a woman with weights, fruit, and water
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If you're like nearly half of the American adult population, then you've likely attempted to lose weight in the last 12 months, per the Centers for Disease Control and Prevention. Weight loss is arguably the No. 1 reason why many people start a new diet. With the weight loss industry booming at an estimated $58 billion in 2022, most adults are frequently exposed to diets with promises of quick, lasting weight loss.

However, some would argue that one of the many reasons why the weight-loss industry continues to grow is because the tactics so often used are unsustainable, with buyers coming back again and again to lose weight. Even if your reason for starting a new diet is unrelated to weight loss, you may have experienced the ups and downs of starting a new diet only to find you've "fallen off the wagon" in a couple of weeks. This common occurrence can be remedied once you understand why a diet "fails" in the first place.

The #1 Mistake People Make When Starting a New Diet

The reasons for starting a new diet are often varied and personal depending on resources, time, preferences and nutrition knowledge. But there's one mistake that most people make no matter what type of diet they choose. "One of the top mistakes I see people make when dieting is taking an all-or-nothing mentality, leaving no room for living life," says Sarah Anzlovar, M.S., RDN, LDN, a dietitian for moms and owner of Sarah Gold Nutrition, LLC.

In other words, many people start a new diet that doesn't offer flexibility for when things don't go as planned. Most popular diets are written for the masses without taking individuals into account. It's expected that individuals conform to the diet's plan versus the other way around. Ultimately, you're left without a path to self-correct when life happens and you "mess up" your diet with a meal that isn't in the plan. "This mindset often leads you to feel like a failure when things don't go perfectly or according to plan," says Anzlovar. "It can also result in ditching any new healthy habits altogether rather than moving on from the moment and continuing on with the changes you're trying to make at the next meal or snack." To avoid the all-or-nothing mentality, skip diets that require you to start over if you go off plan and instead opt for flexible diet changes that fit your lifestyle.

Other Common Mistakes

Even if you don't have the all-or-nothing mentality when starting a diet, you may still find that the diet you choose doesn't work for you. The reasons some diets fail are varied, and what works for one person may not work for the next. Diets that severely restrict total calorie intake or eliminate entire food groups without a medical or nutritional need can often be the most unsustainable in the long run. "Other signs to skip a diet include supplements or shakes that are supposed to replace meals, programs that require you to purchase their food or supplements, very low-calorie diets, anything involving a cleanse, and diets with complicated tracking requirements," says Anzlovar. Many popular diets rely on supplements and restrictions so that followers see results (i.e., weight loss) quickly. However, many people cannot maintain those results, especially if the approach can't be sustained. "None of these things are sustainable in the long term, and if you can't do it forever, the results won't last forever. Many of these qualities can also be more harmful than helpful when it comes to creating healthy habits," says Anzlovar.

The Best Way to Achieve Your Health Goals

No single diet or lifestyle change is best for everyone when it comes to achieving health goals. Because the approach should be individualized, it's best to consider strategies that are accessible and sustainable for your lifestyle. The best way to approach this is by making small, simple changes that you can implement easily. These changes may not seem like much when you first start, but once you add them together, you'll see you've made a significant impact. "Rather than trying to overhaul your entire way of eating all at once, I recommend adding in one healthy habit at a time. Practice it until you get really good at it, then build on that healthy habit with another," says Anzlovar. She encourages this approach because it's more likely to be achievable in the long run. "This leads to sustainable changes that don't feel restrictive or difficult to keep up."

These small changes will look different for everyone based on lifestyle, resources and personalized health goals. "This might look like eating a vegetable at dinner every day, eating a balanced breakfast daily, practicing eating without distractions, drinking enough water or taking a 15-minute walk at lunch," says Anzlovar. It helps to write down your goal and consider all the steps between where you are now and where you want to be. Spend time writing every detail so that you can identify small, actionable steps to help you achieve your goals.

Finally, try to avoid restriction as your primary approach when it comes to making a healthy change. For example, instead of focusing on eliminating a particular food, try thinking about what you'll add in place of that food or alongside that food. "Focusing on what you can add to your diet and lifestyle is a much more effective approach than trying to completely eliminate foods, especially foods you enjoy," says Anzlovar.

The Bottom Line

Ultimately, the best diet or lifestyle change for you is the one you can maintain. Quick fixes and crash diets are unlikely to be the solution to lasting change and could be counterproductive to your health. If you need support when changing your diet, look for a registered dietitian who specializes in your condition or health goal. Guidance from a professional is the best way to ensure your efforts are made to last.

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