4 Types of Diets to Avoid if Long-Term Weight Loss Is Your Goal

When you're looking to shed a few pounds, you might be focused on quick results. And though many diets might help you drop a pants size super fast, you should be asking whether the same eating plan can help you keep off the weight in the long run.

The truth is, weight maintenance can be even harder than the weight-loss process. And, unfortunately, regaining pounds can have negative consequences for your health, according to a study in the October 2019 issue of the Journal of the American Heart Association. Researchers found that all the cardiometabolic benefits associated with healthy weight loss — including improvements in HDL cholesterol, blood pressure and waist circumference, among others — reversed when people packed on the pounds again.

So, when you choose an eating plan for weight loss, consider one that will set you up for success over the long haul. Here, dietary experts discuss the types of diets you should steer clear of if you want to achieve long-lasting results, plus those that will help you go the distance.

Read more: What You Should Know Before You Try That Trendy Diet

"Crash diets that lead to rapid weight loss may sound enticing, but they aren't healthy or sustainable, and they won't help you keep weight off in the long-term," Michele Weinberg, RD, CDN, an associate at NY Nutrition Group, tells LIVESTRONG.com. That's because they often involve eating as few as 500 calories per day, and, though you'll drop pounds (mostly water weight), your body will switch to starvation mode to conserve energy, says Leslie Langevin, RD, CD, author of The Anti-Inflammatory Kitchen Cookbook and co-owner of Whole Health Nutrition, a Vermont-based nutrition counseling company.

The result? Your metabolism slows down and your body may release more cortisol — a stress hormone that can cause inflammation — making future weight-loss attempts even more difficult.

And another thing: Crash diets can result in nutrient deficiencies and muscle loss, both of which can further stall your metabolism and may lead to disordered eating behaviors, such as binging on "off-limit" foods, according to Weinberg.

Not sure if the diet you're considering falls into this category? If it severely restricts calories (less than about 1,200 per day) and/or promises lightning-fast results (anything more than 1 to 2 pounds per week), it likely qualifies as a crash diet.

If you nix a whole food group like carbs, you may shed some pounds — again, mostly water weight — in the short term, but you're not doing yourself any favors in the long-term health department, says Langevin. That's because you risk losing vital nutrients that your body needs.

"For example, cutting out fats can lead us to become deficient in essential fatty acids and fat-soluble vitamins, while eliminating carbohydrates from sources like whole grains, vegetables, legumes and fruits deprives us of essential fiber, antioxidants, phytonutrients, vitamins and minerals," says Weinberg.

Plus, eating too much of another food group can be harmful, too. "People who follow the keto diet have a high intake of saturated fats and processed meats, which, in excess, have been linked to certain cancers, poor gastrointestinal health and an increased risk of cardiovascular disease," says Weinberg.

What's more, excluding an entire food group just isn't realistic or sustainable over time. Are you really going to give up bread for life? Odds are your willpower will eventually run out, and when you reintroduce the "forbidden" foods into your diet, you're likely to regain the weight — often more than you lost in the first place.

The takeaway? Unless you have a food allergy, intolerance or health condition like celiac disease that requires specific dietary restrictions, don't ax an entire food group from your daily menu.

Read more: Is a Gluten-Free Diet Healthy If You Don't Have Celiac Disease?

"Diets that feature meal replacements lead to weight loss because they provide pre-portioned meal options that help people reduce their overall calorie intake," says Weinberg. If you need a fast protein fix or a quick meal-on-the-go, something like a meal replacement shake or bar can be helpful as a snack or supplement, but replacing most meals in this way is overly restricting and unrealistic in the long run, says Langevin.

Over time, you're bound to get bored of consuming the same stuff for breakfast, lunch and dinner, and you're likely to revert to your unhealthy eating habits. That's because when you follow a diet that eschews whole foods in favor of pre-packaged, pre-portioned products, you never learn how to prepare healthy meals on your own, says Weinberg.

In other words, if you want to keep off the weight, you'd need to stick to that restrictive diet forever, which is nearly impossible if you want to dine out with friends, travel or enjoy your favorite foods again.

Plus, when it comes to your health, Weinberg says that weight loss plans that rely on pre-packed meals generally don't stack up against a diverse diet of wholesome whole foods, which "provide a synergistic effect between vitamins, minerals, antioxidants, phytonutrients and fiber that meal supplements and replacements can't replicate."

No doubt you've heard of a diet that boasts, "you'll never need to set foot in a gym again!" Sounds tempting, right? Our advice: Run the other way! Any long-term, sustainable weight-loss strategy should incorporate other healthy lifestyle habits like regular exercise.

Because in order to lose weight from dieting alone, you must consume relatively few calories and progressively decrease the number over time as your body adapts, says Weinberg. The kicker? This gets way harder to maintain as you age.

Indeed, after you turn 30, your metabolism declines slightly each year, says Langevin, who adds that increasing muscle mass is an effective way to keep your metabolism revved up. You can combat this by adding strength-training to your regular routine. That way, you'll build more fat-burning muscle and won't have to starve yourself to keep the muffin top at bay.

Read more: How to Start Exercising in Your 40s, 50s, 60s and Beyond

"The best diet that works for the long-term is one that fits within your lifestyle," says Weinberg, who suggests making two to three small changes at a time to develop healthier habits that will lead to gradual, yet sustainable weight loss.

Need some pointers? Start by focusing on increasing physical activity, practicing portion control, reducing your intake of added sugars, refined grains and processed foods and incorporating fresh, whole foods as much as possible, especially fruits and veggies. Langevin recommends aiming to eat nine servings of fruits and greens every day.

In fact, packing half your plate with fresh produce reflects the U.S. Department of Agriculture's (USDA) dietary guidelines, which also call for splitting the remaining half of your plate between lean proteins like chicken, fish and tofu and whole grains like brown rice and whole-wheat pasta.

The USDA's guidelines also support simple-yet-sustainable eating plans that are easy to follow like the Mediterranean diet, which emphasizes consuming vegetables, legumes, fruits, nuts, lean proteins and extra-virgin olive oil. What's more, the Mediterranean diet may help lower your risk of developing chronic diseases, too.

But to maintain healthy weight loss, you should also build in some wiggle room to enjoy your favorite treats as well. You can nosh on wholesome, nutritious foods most of the time and still indulge in french fries, ice cream and pizza now and again. Doing so will keep you from feeling deprived and falling off the wagon.

At the end of the day, you don't need to be perfect to shed pounds or keep them off. If you're mindful about making healthy decisions when it comes to food and exercise, you're on the right track to steady, sustainable weight loss.

Read more: How to Find the Best Weight-Loss Diet for You