Naturally Thin: What the Experts Say continued...

She likes the idea that no food is off-limits, using the "differential" idea to help you make better food choices, eating mindfully, using small plates, and giving up the guilt if you indulge in one high-calorie bad meal.

But Zied, author of Feed Your Family Right, notes that the template for daily meals may not provide all the nutrients you need, or sufficient calories, she says. Women need at least 46 grams of protein per day, and most should never go below 1,400-1,600 daily calories, Zied says.

"Following this low-calorie plan could make the 'food noise' even louder and readers should be aware there is no science to document that this approach will get the weight off and keep it off for good," Zied says.

Zied is also opposed to skipping meals and consuming too much alcohol, as Frankel describes in some of her sample menus.

"When you skip meals, your body lacks the fuel it needs to keep blood sugar levels normal [and] provide energy, and ultimately the hunger sets you up to grab high-fat, high-salt or sugary comfort foods," Zied says.

She cautions women to follow the 2005 U.S. Department of Agricultural Dietary Guidelines recommendation of only one alcoholic beverage a day -- and to keep in mind that cocktails have calories.

Zied also notes that using the concept of a "bank account" may be difficult without actually counting calories.

"The bank account is a very useful concept when you are trying to change your diet, but initially you need to know how many calories you need, how many you are currently eating, and how many you need to cut to reach your goals," she says.

Once you become familiar with where extra calories lurk and how to make better choices, you can forego the calorie counting, she says. Bottom line: You need a plan if you want to succeed.

Naturally Thin: Food for Thought

There are lots of useful tips, sensible advice, and helpful concepts in Naturally Thin. Although none of this information is necessarily new, these common-sense concepts can help you improve your diet and the way you think about food.

Still, most people need more structure and detail to change their eating habits and gain an understanding of what normal portions look like.

If you want to change your habits and lose weight for good, choose the tips from this book that work for you -- but also consult the U.S. Dietary Guidelines or see a registered dietitian for guidance on planning a balanced weight loss plan that can last a lifetime.

The Naturally Thin plan does not necessarily meet healthy nutritional guidelines, and although it may help you shed a few pounds, it will be hard to sustain the low-calorie intake long term.

Instead of trying to find your inner "skinnygirl," aim for a healthy body weight by eating well and exercising. The truth is that no plan can turn you into a "skinny girl" if your body frame and genetics defy it. Not everyone can be naturally thin.

(Kathleen Zelman, MPH, RD, is director of nutrition for WebMD and the WebMD Weight Loss Clinic. Her opinions and conclusions are her own.)