According to U.S. Secretary of Agriculture Dan Glickman, any type of diet that reduces food intake to approximately 1,500 calories will promote weight loss. It doesn't matter if the diet promotes low carbohydrates, high protein, high fat or even eating like our caveman ancestors -- as long as you reduce your daily intake to no more than 1500 calories, you'll most likely lose weight, and that's why fad diets work.

While I don't recommend that you strictly follow any of these diets (since they're hard to maintain and don't necessarily offer the heart-healthy benefits of a diet based on eating whole grains, fruits and veggies, lean proteins, and good fats), each has some positive points. If you take the best of everything that's out there and fit it to your lifestyle, chances are you'll come up with a winning combination that will help you lose weight today and keep it off next month!

Here are my favorite take-away tips from everyone's favorite fad diets:

1. Learn the pros of protein
Some people don't eat enough protein because they're afraid of the fat content in many protein-rich foods. If you want a healthy immune system and enough muscle mass to handle exercise, you need to eat sufficient amounts of protein on a regular basis. The Atkins plan recommends eating protein at every meal, and doing just that, without going the extra step and dramatically reducing carbohydrate intake, should help promote satiety and decrease snacking.