Over the past 100 years, diet trends have evolved dramatically, with some fads fading into obscurity while others persist, promising quick fixes for weight loss. From celebrity-endorsed liquid cleanses to extreme food combinations, diet trends have often stirred controversy. In 2025, experts weigh in on which of these historical diets were harmless, which were risky, and which ones may still hold value today.
Nutritionists from MyFitnessPal took a close look at iconic diet fads, breaking down the impact of each and offering evidence-backed advice for building a sustainable, healthy lifestyle.
1920s–1930s: The Grapefruit Diet – A Weight Loss Shortcut?
Promoted as a way to “burn fat,” the Grapefruit Diet, also known as the “Hollywood Diet,” involved consuming half a grapefruit before every meal. Despite claims that the fruit’s enzymes could accelerate fat loss, experts quickly debunked the notion.
“MyFitnessPal Senior Lead Nutrition Scientist, Stephanie Nelson, clarifies that while grapefruit is a nutritious fruit that can contribute to a healthy diet, it doesn’t possess fat-burning properties,” she says. She explains that adding grapefruit alone to one’s diet won’t lead to weight loss, and emphasizes that sustainable weight loss requires consistent changes to one’s overall eating habits.
1940s–1950s: The Master Cleanse – A Detox That Does More Harm Than Good
Originally popularized in the 1940s and revived in the 2000s, The Master Cleanse involved consuming a mixture of lemon juice, maple syrup, cayenne pepper, and water, alongside a nightly dose of laxative tea. Promoted as a detoxifying cleanse, its real impact, according to experts, is primarily water and muscle loss.
“This approach is mostly an exercise in starvation,” says Nelson, noting that most dieters regain the weight quickly once the cleanse ends. Experts caution against liquid cleanses, urging that the body’s natural detox systems, such as the liver and kidneys, are more than adequate for detoxification.
1960s: The Sleeping Beauty Diet – Dangerous and Extreme
One of the most extreme diets ever conceived, the Sleeping Beauty Diet encouraged individuals to sedate themselves for up to 20 hours a day to avoid eating. This dangerous trend carried significant health risks, from malnutrition to addiction.
“MyFitnessPal’s Emily Sullivan, RD, warns that this diet is not only unsafe but also harmful to long-term health,” stressing the importance of a healthy sleep routine. She advocates for seven to nine hours of sleep per night, as research has shown both insufficient and excessive sleep can lead to weight gain.
1970s: The Egg & Wine Diet – Unbalanced and Unhealthy
In the 1970s, the Egg & Wine Diet promised quick weight loss by consuming eggs, black coffee, wine, and steak. Experts, however, note the extreme nutrient deficiencies in this diet, with no fruits, vegetables, or whole grains to balance the high alcohol content.
“MyFitnessPal’s Melissa Jaeger, RD, highlights that this diet’s reliance on alcohol and severe restrictions can impair judgment and increase the risk of dehydration and inflammation,” she says. She underscores that these “quick-fix” diets are not sustainable or effective for long-term health.
1980s: The Cabbage Soup Diet – Rapid Loss with Hidden Risks
A brief but notable trend, the Cabbage Soup Diet promised quick weight loss with unlimited servings of cabbage soup, supplemented by small portions of specific foods. But, experts point out that the diet is low in calories and lacks key nutrients like protein and healthy fats.
“Any rapid weight loss from this diet is likely due to water loss and lean muscle, not fat,” says Jaeger. Experts recommend avoiding restrictive diets like this in favor of a balanced eating plan for sustainable weight management.
1990s: The Blood Type Diet – Unscientific and Misleading
Popular in the 1990s, the Blood Type Diet advised individuals to eat based on their blood type, with specific recommendations for each type, such as high-protein diets for Type O individuals and plant-based diets for Type A. However, experts find no substantial evidence to back these claims.
MyFitnessPal’s Brookell White, MS, RD, states that while some studies have shown potential health benefits from eating more vegetarian foods, the diet’s focus on blood type lacks scientific support. She recommends instead focusing on proven, healthy dietary patterns like the Mediterranean diet.
2000s: The Raw Food Diet – Benefits with Caution
Promoted as a way to retain nutrients and enzymes, the Raw Food Diet emphasizes eating uncooked and unprocessed foods, primarily vegan and plant-based. While eating raw fruits and vegetables can offer health benefits, experts caution that an entirely raw food diet may lead to micronutrient deficiencies and other health risks.
Daisy Mercer, RD, explains that consuming raw foods can improve satiety and nutrient intake but notes that the diet may not be safe if it eliminates essential food groups or involves raw animal products. A balanced approach with both raw and cooked foods is ideal for overall health.
2010s: Juice Cleanses – Temporary Fixes with Drawbacks
Juice cleanses, which involve consuming only fruit and vegetable juices for a period, gained popularity as a detox method. However, experts agree that these cleanses are more likely to cause temporary water weight loss than any lasting health benefits.
“Juices may offer a vitamin boost but lack fiber, leading to rapid blood sugar spikes,” says Mercer. She recommends using juice in moderation as part of a balanced diet, rather than relying on it for detoxing or weight loss.
2020s: The Carnivore Diet – Restrictive and Nutrient-Deficient
The Carnivore Diet, which advocates for an exclusively animal-based diet, claims to aid in weight loss and reduce inflammation. However, experts warn that the diet is highly restrictive and lacks essential nutrients like fiber, vitamins C and E, and antioxidants.
White, RD, cautions that the lack of plant-based foods could harm overall health, increasing the risk of heart disease and deficiencies. She advises focusing on a balanced, varied diet rich in fruits, vegetables, and whole grains for optimal health and long-term weight management.
Moving Beyond Fads: Experts Recommend Sustainable Approaches
As history has shown, the best approach to weight loss and healthy living doesn’t rely on fads, but on balanced, sustainable habits. MyFitnessPal’s Melissa Jaeger, RD, recommends focusing on progress rather than perfection. She advises tracking your food intake, building awareness of nutrition, and making long-term, practical changes rather than turning to quick-fix trends.
“Don’t let any diet interfere with your real life,” Jaeger concludes. “Allow yourself to enjoy food in moderation, without guilt, and make choices that align with a healthy, balanced lifestyle.”
Ultimately, experts agree that the key to lasting health and wellness lies in a diverse, nutrient-rich diet, regular physical activity, and a focus on overall well-being rather than extreme dietary trends.
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