Fad diets often promise quick and easy weight loss, targeting individuals looking for a 'silver bullet' solution to their health and weight concerns. However, the science behind these diets and their long-term sustainability is often questionable. A common characteristic of many fad diets is that they tend to be restrictive, cutting out whole food groups or significantly restricting calorie intake. While this might result in rapid weight loss initially, it is usually not sustainable in the long run.