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Trying to Lose Weight? These Are the Diets Dietitians Say To Avoid

December 30, 2022

We’re living in a time where there are so many new diet trends and fads that all claim to be the “best method” for weight loss. Although certain diets can help with different health issues, like your immunity, not all diets were created equal. Just because they can help you lose weight quickly doesn’t mean they’re actually healthy for you, and many dietitians and health experts would categorize them as diets to strictly avoid.

So which weight loss methods should you stay away from this year? We asked experts to share which diets to avoid and had them share healthier solutions for sustainable weight loss that actually works.

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The keto diet is named after ketogenesis, a process where the body uses fat instead of carbohydrates for energy — promoting an extremely low-carb diet. While it may seem like a quick way to lose weight, the keto diet wasn’t actually meant to be a weight-loss diet at all.

“It was created to manage epilepsy by increasing fat in the diet,” explains Catherine Gervacio, RD and nutrition writer for Living Fit. “It became a popular diet because it provides a quick rate of weight change. People nowadays are looking for a quick fix so keto seems to be the best choice. However, since it is too restrictive, it does not promise a long-term solution. Too much protein can also cause kidney problems, high blood pressure, and liver problems.”

“The keto diet may result in initial weight loss but is not a sustainable, long-term solution because its highly restrictive nature can set individuals up for nutrient deficiencies,” says Mia Syn, RD. “It is a very low carbohydrate, high fat, and moderate protein diet. Because the keto diet significantly restricts the consumption of carbohydrates which break down to sugar, the main energy source of cells, the body begins to break down stored fat and protein for energy.”

Intermittent Fasting

Intermittent fasting is setting a schedule for yourself on specific times you can and cannot eat or drink throughout the day, aside from coffee, tea, and water, resulting in weight loss.

“If not done correctly, it can bring about health issues for individuals with diabetes,” says Blanca Garcia, RDN and nutrition specialist of Healthcanal.

There are several types of fasting, including fasting for 16 hours and having an eight-hour “eating window” (The 16:8 method), eating only 500 calories for two days a week (The 5:2 method), eating only 500 calories every other day (Alternate day fasting) and fasting for 24 hours followed by a normal day of eating (The 24 hour fast).

While it may seem like a magical weight loss solution, experts would argue that the success of intermittent fasting is due to the simple act of restriction and setting time limits for eating food.

“The various types of fasting can vary significantly, but it is ineffective for weight loss because it can be so restrictive [making it] difficult to follow,” says Garcia.


Along with specific diets, there are plenty of weight loss programs that claim to help you lose weight fast. Optavia is one of those programs, but dietitians don’t recommend it.

“Optavia is a terrible program to follow for weight loss,” says Whitney Stuart, MS RDN CDCES dietitian and diabetes educator of Whitness Nutrition. “Not only is this program severely restricted in calories, but also food diversity. The more someone is restricted, the more likely they are to binge. I have seen this quick weight loss program build disordered eating patterns faster than anything else.”

While Stuart says that the ease of the program is around convenient calorie-controlled meals, she believes that this can be done healthfully with a variety of real food that considers a balance of macronutrients (aka your carbs, fat, and protein), and is more substantial than just a soy protein isolate carton of chips.

“The goal of changing habits and lifestyle should be around creating sustainable change that aims to give you more nutrition and a better relationship with food,” says Stuart. “This program does the opposite of that.”


When you hear the word “detox” you can associate it with your body getting a cleanse, thinking you will feel better once it’s done. But how safe is a detox, and are they even needed?

“Detox diets are a surefire way to feel deprived, lose weight, and then gain it right back,” says Jamie Nadeau, RDN. “You don’t need to ‘detox’ your body for any reason because our bodies are capable of detoxing on their own. If you have functioning organs, your body is detoxing itself from toxins.

Nadeau continues to say that there are no “detox diets” that are backed by research. Instead, the best way to support your body in feeling and functioning at its best is by drinking enough water, eating healthful foods, and exercising.

75 Hard

A once-viral TikTok trend, the 75 Hard raised some red flags as a fitness and diet challenge to help with weight loss.

“This diet was framed as an opportunity to really commit to yourself and your health by following a rigid plan encompassing diet, exercise, and personal development,” says Cara Harbstreet, MS, RD, LD of Street Smart Nutrition. “It seemed flexible, therefore doable, at first. That’s because it was intentionally vague, saying ‘follow a diet for the 75 days’ but it could be a ‘diet’ of your choosing. However, because of the extreme and time-consuming nature, many people found it challenging or impossible to complete as directed.”

For those who couldn’t meet the standards of 75 Hard, 75 Soft was born. Similarly, Harbstreet believes that, to a lesser degree, this diet is also one to shy away from.

“I can’t recommend these diets for weight loss or wellness because they do so little to support long-term and sustainable habit change,” says Harbstreet. “That means any weight loss achieved, similar to what we see with other diet attempts, is likely to come back and lead to weight cycling or a damaged relationship with food, movement, and body image.”

Better solutions for sustainable weight loss

If there’s anything these dietitians can agree on, it’s that there are healthier ways to lose weight.

“A healthy and effective weight loss program is characterized by a reduced-calorie, nutritionally-balanced eating plan that also incorporates regular physical activity,” says Syn.

Furthermore, Nadeau believes that people who are most successful with weight loss and improving their health, in general, are those who focus on small, consistent changes.

“Instead of trying to overhaul your entire life with an unrealistic diet, choose small healthy habits you can add to your life over time,” she says.

These healthy habits can include increasing fruits and vegetables that are lower in calories, according to Garcia. Other ways are also increasing plant-based proteins like legumes, chickpeas, mushrooms, and lentils. You can also occasionally consume fish while rarely eating intake other meats.

“Most people are likely to follow a diet that they can sustain long-term versus a restrictive diet that they can sustain for short spurts of time, creating a yo-yo experience of weight loss and weight gain,” says Garcia.

Read next: 10 Healthy Weight Loss Soup Recipes That Are Nutrient Rich

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