Over the years, various diet trends have emerged, some quirky and others posing dangerous restrictions. Who hasn’t come across a celebrity-endorsed liquid cleanse or the allure of quick weight loss through odd food combinations? But which of these fads are actually effective, and which are dismissed by nutrition experts in 2025? To assist you in pursuing your health goals for the New Year, MyFitnessPal dietitians have delved into the changing landscape of fad diets to discern their validity. They have also provided evidence-based guidance for establishing a sustainable and healthy lifestyle. Below is a breakdown of the most iconic diet fads over the past century, along with their impact on health, according to experts.
1920s–1930s: The Grapefruit Diet, also known as the “Hollywood Diet,” required consuming half a grapefruit before every meal with the belief that grapefruit enzymes could aid in fat burning. While adding fruit to one’s diet can be beneficial due to its fiber content and low-calorie nature, grapefruit alone does not possess fat-burning properties. Restricting daily calories to 800 as seen in this diet is insufficient for meeting energy needs and may pose risks, especially for individuals taking medications that can interact with grapefruit.
1940s–1950s: The Master Cleanse, or Lemonade Diet, gained popularity in the 1940s and resurfaced in the early 2000s. This regimen involved consuming a mix of lemon juice, maple syrup, cayenne pepper, and water for days to detox and lose weight, supplemented with a nightly laxative tea. However, weight loss from juice cleanses is often temporary and primarily comprises water and muscle mass loss rather than fat. Sustainable weight loss requires long-term dietary changes rather than short-term cleanses, which can potentially lower metabolism and cause dehydration due to unnecessary laxative use.
In conclusion, while incorporating grapefruit into a balanced diet is beneficial, relying on it as a fat-burning solution is unfounded. Liquid cleanses are unnecessary for detoxification, as the body naturally detoxifies through the liver and kidneys. It is essential to focus on a reasonable calorie deficit and nutrient-rich foods for achieving healthy and lasting weight loss goals.
1960s: The Sleeping Beauty Diet
The Sleeping Beauty Diet from the 1960s involved extreme measures where individuals were advised to sedate themselves for up to 20 hours a day to avoid eating during those hours. Nutritionist Emily Sullivan warns that this trend is highly dangerous, as it can lead to malnutrition and potential addiction to sleeping pills. Instead, she emphasizes the importance of getting seven to nine hours of quality sleep per day for weight management and overall health. Both oversleeping and using sedatives to avoid eating are not recommended for a healthy lifestyle.
1970s: The Egg & Wine Diet
During the 1970s, the Egg & Wine Diet gained popularity, consisting of a three-day plan where individuals consumed eggs, black coffee, and wine for breakfast and lunch, followed by steak and wine for dinner. Nutritionist Jaeger advises against this diet, highlighting its lack of essential nutrients like fruits, vegetables, whole grains, and healthy fats. The heavy reliance on alcohol in this diet can lead to nutritional deficiencies and health risks such as dehydration and impaired judgment. Quick-fix diets like this do not promote safe or effective weight loss in the long term.
1980s: The Cabbage Soup Diet
In the 1980s, the Cabbage Soup Diet was a week-long regimen allowing unlimited cabbage soup alongside specific foods like skim milk or fruit on certain days. Nutritionist Jaeger cautions that while the soup may contain various vegetables, it does not provide a balanced diet due to its extreme calorie restriction. Rapid weight loss from this diet is likely temporary and may result in the loss of water and muscle, not fat. There is no scientific evidence supporting its weight loss claims, emphasizing the importance of sustainable eating habits over quick-fix fads.
1990s: The Blood Type Diet
The Blood Type Diet of the 1990s claimed that a person’s blood type determined which foods were healthy for them.
The idea behind these diets is that an individual’s blood type is believed to correspond to their ancestral blood group. For instance, individuals with blood type O were recommended to follow a high-protein, meat-centric diet while limiting vegetarian proteins. On the other hand, those with blood type A were advised to steer clear of meat in favor of seafood and plant-based protein sources.
Registered Dietitian Brookell White, MS, RD, a Food Data Curator at MyFitnessPal, explains that while the concept of these diets may sound appealing, there is a lack of scientific evidence to support their claims. Although a study on this eating approach showed potential benefits for weight management and certain health markers like blood pressure and cholesterol, White emphasizes that the positive outcomes observed in participants were likely due to improved eating habits, particularly the inclusion of more plant-based foods, rather than blood type specificity.
White stresses that focusing on evidence-based dietary patterns such as the Mediterranean diet is more important than tailoring your eating habits based on blood type.
The Raw Food Diet, a dietary trend promoting the consumption of uncooked, unprocessed foods to preserve their natural nutrients and enzymes, has gained popularity. Typically, followers of this diet consume only vegan, plant-based foods.
Registered Dietitian Daisy Mercer, RD, a Food Data Curator at MyFitnessPal, explains that eating raw foods like fruits and vegetables can offer numerous health benefits, providing essential nutrients like fiber, antioxidants, vitamins, and minerals. Consuming raw foods often means reducing intake of processed foods, which can enhance satiety and reduce the tendency to overeat.
Mercer also notes that raw, plant-based foods tend to be rich in vitamins and minerals, as certain nutrients may be lost during cooking. While a diet high in raw foods may offer health benefits, Mercer cautions against following a raw vegan diet exclusively, as it could lead to nutrient deficiencies and other health complications. Moreover, consuming raw or undercooked meats can pose health risks due to potential foodborne illnesses.
Instead of fixating on whether foods are cooked or raw, Mercer recommends focusing on incorporating a variety of plant-based foods into a balanced diet to support overall health.
Juice cleanses, which involve consuming only fruit and vegetable juices for a set period, gained popularity as a detoxification method. However, Registered Dietitian Daisy Mercer cautions that juice cleanses can lead to rapid weight loss primarily due to calorie restriction, not any unique properties of the juices themselves. Without making sustainable dietary changes, individuals are likely to regain any lost weight.
Mercer advises opting for unsweetened, 100% fruit and vegetable juices in moderation as part of a balanced diet rather than relying on juice cleanses for long-term weight management.
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