What is a Fad Diet?

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1 hour ago
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A bowl of colorful salad with greens, tomatoes, and a fried egg. Bold red text reads "FAD DIET" in playful lettering.

A fad diet is a popular, short-lived eating plan that promises fast weight loss or quick health benefits. These diets often make claims that aren’t realistic and require strict food limits. They usually aren’t supported by science and can lead to nutrient shortages or results that don’t last. Most fad diets focus on “magic” foods, label foods as good or bad, push supplements, and promise easy fixes, which makes them unreliable for long-term health.

Fad diets often promise quick weight loss or fast health improvements, but these claims usually aren’t supported by real science. Most of these diets haven’t been tested in clinical studies, so their benefits are unproven. They attract people by offering easy solutions, but they don’t focus on long-term habits or a balanced lifestyle. Many fad diets make big claims like rapid weight loss or detoxing the body, and they often require extreme food restrictions. This can lead to poor nutrition, unsafe practices, or health risks. It’s best to avoid these diets. Even if they help you cut calories at first, they’re usually hard to maintain and may not be safe for everyone. Before starting any diet, it’s wise to talk with a registered dietitian. Examples include the Atkins diet, Keto diet, Paleo diet, and highly restrictive diets like the Grapefruit diet.

Celebrities often promote fad diets, which helps drive sales of related products. Even though the evidence behind these diets is weak, they stay popular. More than 1,500 diet books are published every year, and Americans spend about $35 billion on the diet industry. Around 14–15% of people in the U.S. say they have tried a fad diet for quick weight loss.

Definition

There isn’t one exact definition of a fad diet, because many different diets fall into this category. What people consider a fad diet can vary by time, culture, and opinion. In general, these diets become popular for promising quick results instead of long-term healthy habits. Their popularity doesn’t mean they are safe or effective. The Federal Trade Commission notes that fad diets are usually very restrictive and often missing important nutrients.

Types of fad diets

Fad diets are usually very restrictive and promise fast weight loss or benefits like “detoxing,” but they are not supported by real science. These diets can fall into different groups, such as tests based on body responses (like applied kinesiology), very low-calorie diets that focus on specific foods or liquids, and high-protein, low-carb plans like the Atkins diet. Some even claim to help with serious conditions, such as cancer, even though there is no scientific proof.

In the past, some people mistakenly grouped reputable weight-loss programs, like Weight Watchers, with fad diets. Many factors can influence someone to try a fad diet, including cultural pressures, low self-esteem, and the impact of media and advertising.

Bad diets

Not all fad diets are dangerous, but there are clear warning signs that a diet is giving bad advice:

Promises of fast weight loss over 1 kg (2 lb) per week or claims that sound unrealistic.
Diets that are unbalanced or overly strict, banning whole food groups or allowing only one type of food. Some even suggest you can survive on almost nothing.
Instructions to eat foods in a certain order or combination based on things like your genetics or blood type.
Claims that certain foods can detox your body or magically burn fat.
Promoting an easy “magic fix” without encouraging healthy habits like exercise.
Relying on personal stories instead of solid scientific research from well-designed clinical studies.

Evaluations of Health Claims

Fad diets can lead to different results, but most cause short-term weight loss that usually comes back. These diets may focus on lots of high-fiber vegetables, avoiding grains, or cutting out solid foods, but they are often low in essential nutrients. Following them for a long time can harm your health.

They encourage temporary habits instead of teaching real skills like balanced eating, portion control, and regular physical activity. Because of this, people often return to old habits, regain weight, or even binge eat. Fad diets also fail to address the real reasons behind unhealthy eating patterns.

These diets can raise the risk of heart problems, kidney stones, eating disorders, depression, and dental issues. Long-term low-carb, high-fat diets have been linked to higher death rates. For teenagers, restrictive fad diets can even interfere with normal growth.

Some fad diets can help certain people in the short or long term, especially those with medical conditions like obesity or epilepsy. Very-low-calorie diets, often called crash diets, can reduce liver fat and help people lose weight before bariatric surgery. These diets may cause quick weight loss in the first week or two because the body loses water and stored glycogen, but this weight usually comes back.

Research shows that the biggest factor in successful weight loss is sticking to the diet and creating a calorie deficit, no matter what type of diet it is. Fad diets may help some people get started because they offer structure and match their food preferences or lifestyle. When used under the guidance of a nutrition professional, many types of diets—commercial plans, medically supervised plans, and even some fad-style plans—can be safe and effective both short-term and long-term.

Structured dieting tends to work better than trying to diet alone. As David L. Katz explains, improving public health through nutrition is difficult not because we lack knowledge, but because people get distracted by exaggerated claims and struggle to turn good advice into daily habits.

The idea that “95% of dieters regain the weight” comes from a 1953 study and is seen today as outdated. Newer research shows long-term weight loss is possible with proper support, though a 2007 review found that many people still struggle to keep weight off—one-third to two-thirds regain most of it. This supports the Health at Every Size viewpoint. Some studies also show that long-term calorie reduction can help lower food cravings over time.

Marketing of Fad Diet

Many fad diets claim to be based on religion or science, even though many of their ideas are actually pseudoscience. Examples include “fat-burning foods” or beliefs about special life forces. These diets often rely on exaggerated promises that are not supported by solid research.

Celebrities and well-known “expert” doctors often promote these diets, presenting themselves as gurus while earning money from selling books, products, or speaking at events. A common sign of a commercial fad diet is that you are required to buy special products or pay for seminars in order to follow the plan.

People who try fad diets are often looking for quick weight loss or hope that following a strict eating style will help them make healthier choices in a world full of unhealthy food options. Even though many fad diets lack solid evidence, they remain extremely popular. More than 1,500 diet books are released each year, and Americans spend about $35 billion annually on diet products. Around 14–15% of people in the U.S. say they have used a fad diet for short-term weight loss. Fad diets are part of the larger diet industry, which includes products like “diet foods” and low-calorie drinks.