What is a fad diet? They say you can’t outrun a bad diet, and it’s true. Having proper nutrition is a vital part of maintaining a healthy weight and overall health. But how do you learn about nutrition and figure out what works for you? Many people turn to the internet, which is overflowing with information, or you may be influenced by family, friends, colleagues, and celebrities on social media. These paths usually lead people to fad diets. Fad diets are usually not sustainable, supported only by personal stories, not backed by science, and can lead to yo-yo dieting. So how do you know whether a diet is a fad? They are usually restrictive, promise unrealistic results, and are expensive or unsustainable.