You finally made the commitment and you're ready for a diet -- but what's next? Before you rush out to get the latest diet book, make sure you know what you're getting.

Nutritionist Leslie Beck has rated four of the most popular diet books on the market using a five-star system that breaks down as follows:

1 star - if the diet contains healthy foods or is nutritionally adequate
2 stars - if it's easy to follow and not cumbersome in terms of measuring
3 stars - if it educates about portion sizes and menu planning
4 stars - if it is sustainable over the long term
5 stars - if it also promotes exercise and other important factors associated with weight loss success

Beck's five-star rating is about making a lifestyle change, not a quick-fix success.

The Atkins Diet
Dr. Atkins' New Diet Revolution by Dr. Robert Atkins

"This is a low-carb diet," Beck explains. "For two weeks you basically give up carbohydrate foods. That means no dairy products, no fruit, no sweet vegetables and no starchy foods like grains, cereals or pasta."

It promotes high animal-fat foods such as meat, cream and butter, Beck says. After the induction phase, you gradually add back in five grams of carbohydrates every week. That's the cumbersome part, she explains. You constantly have to be counting all the carbs in your diet.

"Some of the drawbacks of this diet are that it's not sustainable in the long term," Beck says. "Eventually people will be adding back in carbs and what I've seen in my practice is people are doing that with high-fat foods as well. We know that a long-term intake of meat may increase the risk of colon and prostate cancer and there are experts who are very concerned that if you follow this diet for a long time, you're not getting fruits, vegetables, fibres and antioxidants, which means you may increase your risk for heart disease."

Beck's rating: 1-1/2 stars

The South Beach Diet
The South Beach Diet by Arthur Agatston

"It's a healthier version of the Atkins Diet," Beck says. "For two weeks, you eat no carbohydrates. But after those two weeks, this diet promotes the low glycemic index --  healthier carbohydrates that take longer to digest, things like fruits, dairy products and whole grains."

It doesn't promote foods that are high in animal fat. Instead it suggests fish, chicken and healthy fats.

"From that standpoint it's much healthier (than the Atkins Diet). It contains mostly healthy foods and it's easy to follow. The drawbacks of this diet is that it doesn't really educate very well about portion size when you add back in those healthy carbs."

Beck's rating: 3 stars

The G.I. Diet
The G.I. Diet by Rick Gallop

"This is a well-balanced diet," Beck reports. "it doesn't exclude any food group and it really emphasizes low-fat meat, fish for the heart, as well as low glycemic index carbs."

This scored very high because it's practical, she added. The only drawback is it didn't provide a lot of good information about serving sizes and menu planning.

"It's very healthy. The author categorizes foods into red-light foods which are processed and high in fat and/or calories; green-light foods, which you can eat as much as you want to in the first phase, and they're all low glycemic index, very healthy foods."

Your dinner plate is divided into quadrants, a quarter for the protein, a quarter for the low glycemic starch and half for vegetables.

Beck's rating: 4 stars

The Ultimate Weight Solution
The Ultimate Weight Solution by Dr. Phil McGraw

"There's really nothing new here," Beck said. "It is based on mostly healthy foods that are associated with a lower risk of heart disease. The author promotes chicken, fish and low-fat foods."

Like the G.I. Diet, the plate is divided into quadrants, quarter protein, quarter starch and half vegetables.

"This diet really skims over nutrition in a simplistic way," Beck explained. "He takes the good, healthy foods and calls them 'high response' or 'high yield' foods -- foods that take longer to prepare, longer to chew and digest, and they're healthy so they're better for you. And the foods to avoid are the 'low yield' or 'low response' foods."

Beck's rating: 3 stars