By Summer Banks FNS, SPT on Oct 06, 2020

Why diets never work – the term diet has been used for hundreds of years to describe how we eat, the foods we choose, and our dietary intake, but in the recent decade, the term has taken on a negative meaning. Dieting for weight loss is one of the most popular lifestyle changes made today, and, unfortunately, it’s likely one that won’t turn out the way you expected.

What is a weight-loss diet?

In terms of weight loss, what makes a diet a diet and not a normal eating plan? A diet is one you adopt to lose weight, typically consuming fewer calories, fat, or carbohydrates than a traditional diet. The dictionary actually shares a definition focused on weight loss. The verb form means “restrict oneself to small amounts or special kinds of food to lose weight.”

The term restrict immediately pops out. Going back to the dictionary, we can see that restrict means to reduce, limit, constrain, control, cutback, regulate, and the like. In a basic form, a diet is a restriction you place on eating – and restriction is a recipe for disaster.

The Korean Journal of Family Medicine puts the problem with why diets never work perfectly. “The misunderstanding of the concept of dieting should be corrected, and appropriate concepts should be adopted into local culture and food habits.”

The list of weight-loss diets is a mile long, with some of the more common being low-fat, low-carb, and low-calorie.

Closer Look at the Most Popular Weight-Loss Diets


A low-fat diet is one that restricts fat intake, typically in the form of cholesterol, saturated fats, and trans fats. While the main focus of the diet is on heart health, the diet is also commonly used for weight loss. So, what does science say about the long-lived low-fat diet?

Research in The Lancet shows that, over the course of reviewing more than 50 studies on low-fat diets, lower-fat interventions were no more effective at promoting weight loss than lower carbohydrate diets. Low-fat and moderate-fat diets showed the same results.

In 2016 research in Clinical Nutrition, low-fat diets, which promoted intake of more carbohydrates, actually led to a higher risk of metabolic syndrome. Metabolic syndrome is a group of various symptoms that, when combined, increases the risk of certain diseases, high cholesterol, and abdominal fat stores.

Research has long proven that low-fat diets are nothing special. In a 2002 review of research, the Cochrane Database revealed that “fat-restricted diets are not better than calorie-restricted diets in achieving long-term weight loss in overweight or obese people.”

So, we know low-fat diets aren’t the best option for weight loss, but what about the ever-popular low-carb diet?

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The low-carb diet, whether via Atkins or the new keto trend, is nothing more than restricting carbohydrate intake to the point that the body needs to turn to fat for energy. Fat stores are burned, and you lose weight, but is low-carb any more effective than other weight-loss options?

The big no-no in low-carb dieting isn’t whether or not eating fewer carbs promotes weight loss because we know it does, if only in the short term, it’s with the fact that no long-term effects have been noted. Studies just haven’t lasted long enough to give us a clear understanding of the impacts of restricted carb intake on body functions and overall health, according to the American Journal of Epidemiology.

As if the lack of research wasn’t enough to turn someone away from a low-carb diet for weight loss, the fact that research shows just how poorly the studies were completed and controlled is enough to make anyone second guess the results, as per Obesity Reviews.

The Asia Pacific Journal of Clinical Nutrition agrees that more research is needed to realize and report the possible long-term effects of low-carb. There’s simply not enough research to support a long-term healthy low-carb diet.

So we know that low-fat diets are no more effective than other diet plans and low-carb diets haven’t been tested over the long term for weight loss, what about the old tried and true low-calorie or very-low-calorie diet?


A low-calorie, or very-low-calorie, diet is one that aims to reduce the number of calories you take in to less than the amount the body needs to function each day. This negative balance then causes weight loss on a fundamental level. So, what’s the real deal with the eat less/move more mentality?

In the 1970s, the idea was that significantly reducing calorie intake was the right idea for weight loss. Overall, in the short term, the VLCD diet was no more effective than a more standard low-calorie diet, according to the journal Obesity (Silver Spring).

So, to start, the low-calorie diet is not necessarily more effective at helping you lose weight, based on 2017 research in Perspectives on Psychological Science. The research concluded that a low-calorie diet, “by itself…will have limited short-term influence.” You can’t just eat less to lose weight, that’s not how the body works.

Moving on to very-low-calorie diets (VLCD), you move into the medically-guided weight loss realm. Men and women take on the challenge of trying VLCD to lose weight, and these diets are often successful for the very short term. Once hunger takes control, you may find you gain all the weight back and then some.

One of the first things to consider with a VLCD is safety. As far back as 1983, journals like the Annals of Internal Medicine shared concern that very-low-calorie diets are only safe when followed short-term under the guidance of a qualified healthcare provider.

Another problem with VLCD is the dropout rate. When you can’t eat enough food to keep you full, you may turn to food in desperation once you feel overwhelmingly hungry. People just don’t stick with a VLCD because it’s just too hard on the body, according to Drugs and Therapeutic Bulletin.

After reviewing the top three weight-loss diets and seeing just why diets never work, let’s take a look at some of the more extreme diet changes that have no business in the same sentence as “safe weight loss.”

Extreme Diets

What Extreme Diets to Avoid

Cabbage soup diet: The cabbage soup diet is one of the oldest around. With a recipe that’s taken on many versions over the years, the basic premise is to make soup out of cabbage and various other vegetables and eat that for three to seven days.

Why avoid it? The calories and nutrition provided by the soup are far less than the body needs. The only possible way to include the cabbage soup into your diet, in a healthy way, is to include it as part of intermittent fasting.

Master cleanse: The Master cleanse is another oldy, but it continues to pop up in the news, often in celebrity circles, every once in a while. The Master cleanse uses a combination of ingredients like apple juice and apple cider vinegar to promote weight loss.

Why avoid it? Much like the cabbage soup diet, the Master cleanse doesn’t provide the calories or nutrition needed to support good health. Of the two – cabbage soup and Master cleanse – at least the cabbage soup diet has some calories and some nutrition.

Weight-loss tea: The typical weight-loss tea is a combination of herbs, laxatives, and natural diuretics. The weight you lose has nothing to do with fat stores. Instead, you are losing water weight, which you will gain back as soon as you stop drinking the weight-loss tea.

Why avoid it? When you lose water weight unnaturally, as is the case with natural diuretics and weight-loss teas, you can also lose electrolytes like sodium and potassium that are needed for many essential body processes.

Clean eating: If you were to look for a reliable source of information on the history of clean eating, you’d be hard-pressed to find anything. There’s no indication of when this trend started, and the definition depends on who you ask.

Why avoid it? With no definitive background and precise definition, clean eating is nothing more than a fad with no clinical support.

Activated charcoal: One of the newest detox diets out there is the activated charcoal diet. In the 80s, some research showed charcoal may help ease digestive and gastrointestinal discomfort. From there, the idea of detoxing the body was born, though no science supports the claims. What science does say is that activated charcoal can help relieve gas and bloating.

Why avoid it? There’s simply no evidence, of any kind, that links activated charcoal to body detox or weight loss.

Green/detox diets: The green/detox diet is all about the cucumbers, lettuce, kale, and other fruits and vegetables. For anywhere from three to seven days, you drink only green smoothies made from natural ingredients. In some cases, protein powder is used to balance out nutrition, especially when following a green diet for more than a few days.

Why avoid it? There’s no way to get enough nutrients and protein from green smoothies with only fruits and vegetables. Plus, some fruits are actually packed with natural sugars and tons of calories, which could drive the number of calories in each smoothie higher than some meals.

Collagen: Another big trend right now across beauty, weight loss, and overall health is dietary collagen. The body typically gets all the collagen it needs from meat sources, but supplementing has grown popular in recent years. In two studies, with a total of around 50 participants, collagen as gelatin increased the feeling of fullness after eating.

Why avoid it? There’s not enough science to show just how collagen supplements can benefit weight loss. We do acknowledge that further research is needed in the field.

Saltwater cleanse: A saltwater cleanse or saltwater flush is supposed to cleanse your system and help you lose weight. The problem is that saltwater has a laxative effect, so you spend more time in the bathroom, which is where the weight loss comes in. You’re losing water weight, not fat.

Why avoid it? The laxative effect can be harsh on the bowel system and, if misused, laxatives can make it difficult to move waste without a laxative. To top it off, you’re not losing weight you’re losing water.

Fasting: Intermittent fasting has some solid research behind it, but extreme fasting is nothing less than dangerous. Strict fasting involves going for days with nothing other than water or other non-nutritive drinks, broth, and clear soups. The daily intake of calories can be as low as 300-500, which is not enough to keep the body moving, let alone healing, rebuilding, and restoring.

Why avoid it? There are no trustworthy guidelines for extreme fasting and no medical precedence that weight lost while fasting will stay off once you return to eating whole foods.

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Research on Diets and Why They Don’t Work

Let’s take a look at some additional research that further explains why diets never work. From reducing calories to restrained eating and more, there are many pitfalls to avoid in successful weight loss.

Reducing calorie intake may not help you lose body weightPerspectives on Psychological Science

Cutting out calories will not affect long-term weight loss if you don’t learn how to eat and what calorie-control looks like over time to prevent weight gain.

Dieting and restrained eating as prospective predictors of weight gainFrontiers in Psychology

There’s no better way to explain how this research into restrained eating and dieting came out than with a simple quote from the study. “Individuals who diet do so because they are resisting a powerful predisposition to weight gain which dieting ultimately fails to prevent.”

On the futility of dietingMedscape General Medicine

The lack of information on and consideration of portion sizes is another reason why diets never work. Just because you eat foods that are lower in calories, carbs or fat doesn’t mean you’re eating the right portion sizes. In many cases, reducing portion sizes of currently eaten foods may promote just as much weight loss as eating more substantial portions of “healthier” weight-loss foods.

Maintenance of lost weight and long-term management of obesityThe Medical Clinics of North America

In 2018, when 29 weight-loss studies were reviewed, more than 50% of the weight loss in the studies was regained over the next two years. Diets never work because they don’t teach people how to eat, what to eat, when to eat, or any habits or lifestyle changes to keep the weight off.

Why weight loss maintenance is difficultDiabetes Spectrum

Again, touching on the difficulty of weight-loss maintenance, we find that despite the idea that keeping the weight off is easy, research has shown, “weight-loss maintenance…is not that simple.”

“They all work…when you stick to them”Nutrition Journal

Probably one of the most eye-opening studies puts the fact about why diets never work into perspective. Diets are hard to stick to because they are so restrictive and, unless you stick with a diet, it’s never going to work.


The Dangers of Dieting

There are also inherent dangers to dieting that some people may not take into consideration, or even know exist.

In explaining why diets never work, we can’t move past the concept that dieting promotes some poor eating habits, including a preoccupation with food, food distraction, fatigue, overeating, and irritability, even in adolescents, according to Paediatrics and Child Health.

What about weight-cycling? Current research shows that weight cycling, the process of losing weight then regaining the weight, may actually be a contributing factor in the prevalence of obesity. It appears that regaining weight causes a resurgence of inflammation, common with overweight and obesity, that may increase the risk of certain weight-related issues, according to the International Journal of Exercise Science.

The dangers of dieting affect more than just adults. In young adulthood, the risk of disordered eating, like binge eating or severely restricting food intake, increases when these young adults go on a “diet” to lose weight, according to the Journal of the American Dietetic Association.

Why Diets Never Work Ingredients
Bottom Line

So, What’s a Better Answer Than Dieting for Weight Loss?

We now know why diets never work, but what can we do to lose weight and keep it off for lasting health and longevity? How about learning about nutritional eating, portion sizes, and the impact of movement on metabolism, weight and certain body and disease processes. Science also has a few things to say about what works and what doesn’t.

The Buddy System

First, let’s take a look at how interacting with someone else, a buddy, during your weight-loss journey, helps you reach your goals and stick with the results long-term. Based on 2018 research in the Journal of Health Communication, people who enrolled in a buddy system during weight loss maximized the effectiveness of the program.

Supervised Weight-Loss

When you have someone there to help you along the way, you are more apt to lose weight than if you are dieting alone. A coach is the perfect means of staying on track because when you get answers to questions or just need a helping hand when you think you are going to fail. This can keep you in the running for success, according to Patient Preference and Adherence.

A Personalized Approach

Research also shows that when you adopt a more personalized approach, as opposed to just a generic diet, you lose more weight over time, according to Digital Health.

Set a Realistic Goal With a Balance Diet

You don’t have to adopt some extreme diet, or a diet at all in the weight-loss sense, to lose weight. Research shows that setting realistic goals for weight loss and adopting a balanced eating plan is what works best. These changes don’t have to be difficult to adopt or maintain, if they are taught clearly, with simple lifestyle modifications over the long term, according to Healthcare.

Intermittent Fasting

Believe it or not, intermittent fasting (IF) has been shown effective in weight loss. The idea behind IF, as opposed to extreme fasting, is that there are ground rules established by research that help you make the most of your food-less hours. Intermittent fasting can be as simple as fasting from 8 pm to 10 am the following morning and eating nutritious foods the rest of the day, according to Current Obesity Reports.

Why diets never work – because dieting is not a lasting means of eating what the body needs to sustain healthy function while reaching and maintaining a healthy weight. You don’t have to restrict certain foods, eat far too few calories, or adopt disordered eating to lose weight. The best way to lose weight is through realistic goals with personalized support and a weight-loss buddy who helps you make gradual changes you can live with for life – like the weight-loss app Noom. Download your free trial offer today!

About the Author:

Summer Banks has researched over 5000 weight-loss programs, pills, shakes and diet plans. Previously, she managed 15 supplement brands, worked with professionals in the weight loss industry and completed coursework in nutrition at Stanford University.