Most Fad Diets Fail Because


What is considered a fad diet?

The British Dietetics Association states that a fad diet is “a plan that promotes results such as fast weight loss without robust scientific evidence to support its claims”. There are several fad diets you may have heard in passing conversations, popular ones include:

·  Keto diet

·  Low-carb diet

·  Atkins diet

·  Mediterranean diet

·  Grapefruit diet

·  Paleo diet

·  Cabbage soup diet (is a mono-diet)

·  Dukan diet

·  South beach diet

·  DASH diet

Though all these diets limit or eliminate certain food groups or even macronutrients (i.e. carbohydrates, protein or fats), they all have the same underlying philosophy: to create a restrictive food plan that includes stage food combinations to reduce your calorie intake in order to achieve weight loss. These diets often include overly expensive foods and/or supplements that are unnecessary, and some may even dictate the times you can eat certain foods. Fad diets are unsustainable due to their restrictive nature, and at times can be harmful. There are a multitude of reasons fad diets fail, all of which will be discussed below.

1. They backfire1

Most fad diets work by suddenly significantly restricting your calorie intake. This may be great as you see an immediate reduction in your weight, thus, leading you to believe that the fad diet is effective. But research has shown that fad diets frequently ‘backfire’, whereby individuals may experience an increased likelihood and intensity of binge-eating behaviour whilst partaking in fad diets. Individuals have reported that if they consume as little as one unplanned food item, they feel as though they have failed themselves, as well as all the dieting effort they have put into that point in time. Following one dietary violation, dieters have reported that future ‘episodes’ of binge eating become more likely. Thus, the majority of dieters partaking in fad diets may find that these diets ‘backfire’, as restricting calories or certain food groups tend the dieter to feel hungrier, ultimately leading to a diet-binge cycle.

2. They aren’t effective1

Due to how popular certain diets can be, it can be surprising that none of them are based on actual nutritional or medical research. Most of these diets follow the basic principle of lowering your calorie intake by restricting certain food you can consume, which does prove to be effective short-term when you first experience rapid weight loss. However, low levels of effectiveness are typically reported across all fad diets due to the lack of adherence to the strict rules that are placed on dieters. Though short-term, rapid weight loss can be experienced following fad diets, the first bout of weight loss is not maintainable. Thus, instead of significantly reducing your calorie intake or limiting foods from a certain food group, for effective weight loss, we should focus on slowly reducing our calorie intake over a long period of time and not impose extensively strict and rigid rules.

3. Lack of nutrients

Some fad diets, especially ones such as the cabbage soup diet or grapefruit diet, are classed as ‘mono-diets’. Essentially in these diets, as their name suggests, dieters are only ‘allowed’ to consume the meal or food item for several days or weeks, depending on the length of the proposed diet. As with other fad diets, these mono diets induce weight loss by decreasing food intake. When consuming a single food item or meal, especially low-calorie food items such as vegetables, you are likely to consume less than you typically would, which is the underlying principle of these diets. However, consuming a single food item, such as grapefruits, significantly reduces the diversity of your diet and, thus, the nutrients provided to your body through food intake. Though mono-diets are typically unsustainable, if done for long periods of time, these diets can be extremely damaging to your body as nutritional deficiencies can increase your risk of anaemia (i.e. lack of red blood cells in the blood), impaired immune system, digestive conditions, muscle and bone mass loss, and a range of chronic diseases.2 Mono-diets, out of all fad diets, lack the most scientific research, meaning there has been no research assessing their safety, feasibility and effectiveness.

4. Motivation1

As briefly mentioned earlier, adherence is a prominent determinant when assessing the success of different dieting methods. Despite knowing that eating less will lead to weight loss, we all know that weight loss is not as straightforward as simply doing so. Throughout a ‘diet’, one’s self-control and determination to follow the strict rules of fad diets may be extremely high at times and low at others. Moreover, suppose an individual has already had a previous experience or multiple experiences of failure with fad diets. In that case, they are less likely to achieve successful weight loss as single or repeated failures can significantly impact one’s mental health. Fad diets can not only be harmful to one’s body physically but also mentally, whereby decreased self-esteem, self-blame, lack of control, difficulties concentrating, anxiety, and depression have been commonly reported following a diet failure.

5. They’re not sustainable

Most fad diets promote unsustainable and unhealthy diet and lifestyle habits. Fad diets promise dieters fast weight loss results, which may provide short-term success. However, it has been reported that most individuals following fad diets regain 30-50% of the weight lost within 1 year and 50% of dieters will return to baseline weight within 5 years.3

6. Everybody is different

Fad diets are being popularised not through robust scientific research but typically through ‘success stories’ shared by friends, families or even self-proclaimed nutritionists and/or fitness influences on social media platforms. In an age of rapid technological advancement, these ‘success stories’ of significant weight loss after following certain fad diets are everywhere, leading many people to believe that what worked for others will work for them too. However, this is not the case more often than not, as every human being is different. This occurs because of differences between individuals’ genetic/biological make-up. Using fruit flies, researchers have demonstrated that an individual’s gene can significantly impact the success or failure of certain diets, whereby our genes are shown to interact with the foods we consume, causing between-subject differences in metabolic traits, and body weight.4

7. Trends change

Social media has increasingly become intertwined with our everyday lifestyles, and in many cases, we allow the perception of others online to dictate our lifestyle choices, both consciously and unconsciously. Studies have shown that individuals attempting to lose weight, whether by exercise or dieting means, are all strongly influenced by the opinions and attitudes of their informal social network.5 Coupled with new diets invented seemingly every week, it is hard to know which diet is best to follow. The wide range of variety, though helpful in providing inclusion, can easily just as well confuse new dieters as to what should be followed and what should be avoided. To achieve weight loss, consistency is a major component. A study investigating dietary consistency and weight management found that when comparing those who do not maintain a consistent diet, those who have consistency in their diet are 1.5 times more likely to maintain their weight within ~2.3kg over a year. Thus, with fast-changing trends in fad diets, dieters who experiment with new diets often are unlikely to achieve successful and maintainable weight loss.6, 7

8. They can be dangerous1

In addition to the already mentioned harmful physical and mental effects certain fad diets can cause, they have also been found to be a major risk factor for developing eating disorders. It has been shown that those who diet are 5 times more likely to develop an eating disorder compared to individuals who do not diet.  Moreover, it has also shown that changes in appearance are the reason for most dieters to achieve weight loss, and in some cases, dieters have voiced that if given a choice, they would likely sacrifice their health if it meant that they could lose weight. Fad diets promote obsessive behaviour in what you are allowed to or not allowed to eat, which is constantly monitored, can be unhealthy and dangerous, especially if eating disorders such as anorexia are developed as a result.

9. They are restrictive1

Fad diets, such as keto or low-carb diets, restrict or reduce consumption of an entire macronutrient group, limiting fat and carbohydrate intake, respectively. Due to the restrictive nature of dieting, dieters have reported increased thoughts of food or eating, even though they are attempting to achieve the opposite, which is to suppress these thoughts. Constant food- or eating-related thoughts can greatly challenge one’s self-control. Moreover, if one does give in to their need to consume a restricted food item, dieters have reported an incapability to consume desired food items in a moderate amount, which ultimately leads to binge-eating cycles and food obsessive behaviour that likens addiction.


Making lifestyle changes and creating healthier habits will be better than fad diets. Slow reduction of calorie or food intake over a long period of time and consumption of ‘guilty’ foods in moderation is generally recommended to achieve long-term, maintainable weight loss.


1. Buchanan K, Sheffield J. Why do diets fail? An exploration of dieters’ experiences using thematic analysis. Journal of Health Psychology. 2015 Dec 16;22(7):906–15.

2. Institute of Medicine (US) Committee on Military Nutrition Research. Nutrition and Immune Responses: What Do We Know? [Internet]. National Academies Press (US); 2016 [cited 2019 Aug 21].

3. Blomain ES, Dirhan DA, Valentino MA, Kim GW, Waldman SA. Mechanisms of Weight Regain following Weight Loss. ISRN Obesity. 2013 Apr 16;2013:1–7.

4. Why fad diets work well for some, but not others [Internet]. ScienceDaily.

5. Thomas SL, Hyde J, Karunaratne A, Kausman R, Komesaroff PA. “They all work...when you stick to them”: A qualitative investigation of dieting, weight loss, and physical exercise, in obese individuals. Nutrition Journal [Internet]. 2008 Nov 24 [cited 2019 Sep 6];7(1).

6. Rosenbaum DL, Schumacher LM, Schaumberg K, Piers AD, Gaspar ME, Lowe MR, et al. Energy intake highs and lows: how much does consistency matter in weight control? Clinical Obesity. 2016 Mar 29;6(3):193–201.

7. Gorin AA, Phelan S, Wing RR, Hill JO. Promoting long-term weight control: does dieting consistency matter? International Journal of Obesity. 2003 Nov 25;28(2):278–81.

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