While there is no set approach to identifying a fad diet, many have the following characteristics:

• Recommendations that promise a quick fix.
• Claims that sound too good to be true.
• Dramatic statements that are refuted by reputable scientific organizations.
• Eliminating 1 or more of the 5 food groups. Depriving our bodies of needed food groups is a bad idea. It's better to eat smaller portions in well-rounded meals (meals that contain servings of protein, grains, fruits, and veggies). When your body gets the right balance of nutrition, it's less likely to have cravings. Eating smaller portions also helps you set good eating habits that will help you keep the weight off.
• Diets focusing on 1 food group. 
• The diet is based on taking special pills, powders, or herbs. These are usually just gimmicks. For most diet supplements, there's no reliable scientific research to back up their claims. And doctors consider diet supplements risky for teens because not much is known about how the ingredients affect the growing body.
• The diet substitutes non-foods for foods. Diets that center on eating their special meals, or special bars should send out the red flag.The best diets focus on healthy, unprocessed fresh food, including healthy amounts fruits, low fat protein, vegetables.
• The diet focuses on cleansing. A big part of losing weight through cleansing diets is through their laxative effect. This is not a good practice for long term weight loss. Also, it doesn't provide any of the "mouth feel" that makes normal food satisfying and as a result many people on these types of diets tend to overeat the moment they are done with this type of diet.
• The diet makes you completely cut out fat, sugar, or carbs. Depriving our bodies of needed food groups is a bad idea  ((for example, high-protein diets suggest significantly reducing the percent of carbohydrates in the diet, an important component of the recommended eating guidelines based on the food pyramid).  rather than exclude a particular food group it is better to eat smaller portions in well-rounded meals (meals that contain servings of protein, grains, fruits, and veggies). When your body gets the right balance of nutrition, it's less likely to send you willpower-busting cravings! Eating smaller portions also helps you set good eating habits that will help you keep the weight off.
• The diet tells you to eat only specific foods or foods in certain combinations. There's no reliable scientific proof that combining certain foods works. And limiting the foods you eat means you might not get all the nutrition you need.
• the diet promises too much weight loss too soon.Typical healthy weight loss is considered one to three pounds a week.
  
• Dire warnings of dangers from a single product or regimen or food.
• Recommendations based on a single study.
• Recommendations based on studies published without review by other researchers.
• Recommendations based on small studies.
• Recommendations from studies that ignore differences among individuals or groups.
• Recommendations made to help sell a product.
• Promises success for everyone.
• "White Coat" sales tactics, where a doctor you never heard of claims to be an expert on the subject and is pitching a specific product, especially if it is his own.