Are fad diets a good idea? Plus healthy tips to take away from the fads.

Are fad diets a good idea? Plus healthy tips to take away from the fads. Watch: Veggie-Packed Minestrone Soup Recipe

Fad diets may sound like a good idea but they usually make ridiculous promises and can't deliver. Sure, you may drop 10 pounds in a week eating cabbage soup, and little else, but it's water weight, not fat. Once you go back to eating like a normal person you'll gain it right back. That's the biggest problem with most fad diets: they generally don't give you eating patterns that you can stick to long-term. Essentially, they set you up to fail. But there are kernels of truth buried in the shaky "science" of many popular plans-real advice that will help you lose weight healthfully. Here are 6 weight-loss secrets hidden in fad diets...and how to apply them with common sense to your own healthy weight-loss plan.

Featured Recipe: Veggistrone

1. Eat delicious foods that you love. The bottom line of French Women Don't Get Fat: The Secret of Eating for Pleasure by Mireille Guiliano: food should be savored and enjoyed. Guiliano and French women are right: We should continue to eat foods that we love, like chocolate and cheese-just in smaller portions. Deprivation diets only work for a short time. Making room for a small treat every day can help you stick to an overall-healthy eating plan for the long haul.

2. Keep things simple. Celebs like Jennifer Hudson and Kelly Clarkson have reportedly tried Dr. Siegal's Cookie Diet-which prescribes six pre-packaged cookies, plus a one real meal every day. The beauty of this plan is, well, you just eat what you're told. But you don't need "appetite-suppressing" cookies (there's no science to show they really work) to cut calories. To minimize the hassle of planning and cooking meals try cooking a lot on Sunday and then portioning out healthy meals that feature lean proteins and vegetables for easy lunches and dinners throughout the week.

3. Have some lean protein, good carbs and lots of veggies. According to "The Zone" diet, created by Dr. Barry Sears and made famous by big-name followers like Jennifer Aniston, meals that are precisely 30 percent protein, 30 percent fat and 40 percent carbohydrates can reset your metabolism in a way that results in weight loss, reduced risk for heart disease and loads more energy. Sears' super-exact 30-30-40 formula doesn't have hard science behind it, but meals like the ones he suggests-a small amount of lean protein, such as salmon, paired with "favorable" carbohydrates, like vegetables and whole grains-do tend to be more satisfying. Science shows that gram for gram, protein tends to be more filling than carbohydrates or fat. Vegetables and whole grains contain fiber, which causes you to digest them more slowly than refined carbohydrates like white pasta or white rice.

4. Don't be afraid of fat If the Atkins' diet taught us anything, it's that following a fat-free diet isn't always the best way to lose weight-especially if your favorite fat-free foods are big, caloric bagels. Then, the more sensible South Beach Diet came along and taught us to opt for healthy fats, like almonds and fatty fish, over the non-stop burgers and bacon that Atkins permitted. South Beach also encouraged carbohydrates that fall low on the glycemic-index (i.e., they don't cause rapid spikes and drops in your blood sugar)-vegetables, whole grains like brown rice and barley. And we all should adopt the philosophy that judicious amounts of healthy fats trump unlimited refined carbs any day.

5. Soup can help you lose weight. The anonymous creator of the "Cabbage Soup Diet" was onto something: soup (based on a low-calorie veggie, like cabbage) very well may help you lose weight. Various studies show that soup is highly satisfying. In one study, published in the journal Physiology & Behavior, people consumed the fewest calories on days when they ate soup. Broth-based soups packed with vegetables and lean proteins or fiber-rich beans give you the biggest bang for your caloric buck.

6. Keep an eye on sugars. The Zone, South Beach, Sugar Busters and Atkins, all advocate cutting back on sugars and that's a good idea no matter which eating plan you follow. Some foods naturally contain sugars, like fruits and dairy, and are still healthy choices because of all the other nutrients they deliver (think fiber, calcium, vitamins, etc.). But most people eat far too much added sugar and cutting down on that is healthy choice. The average American consumes about 355 calories of added sugars each day. The American Heart Association recommends women to eat no more than 100 calories per day from added sugars (that's about 6 teaspoons) and men to stick to less than 150 calories, approximately 9 teaspoons. "Sugars" on Nutrition Facts panels include natural and added sugars, so check ingredient lists for sugar and all its aliases: corn syrup, honey, molasses, etc. The closer sugars are to the top of the ingredient list, the more the food contains.