The skinny on diets

The new food guidelines are going head-to-head with an unprecedented buzz for fad diets stack up next to the United States Department of Agriculture’s (USDA’s) Dietary Guidelines.

1. The Glycemic Index

What it is:

The Gylcemic Index (GI) diet encourages consumption of slow-burning carbs that release sugar slowly into the bloodstream. The speed at which a food is digested is measured by the GI, which scores glucose at 100 and rates other foods against that number.

How it measures up:

Nutritionists like the GI diet for pushing lots of fiber in the form of whole-grain products and a variety of foods. However, it differs from the USDA in that some unlikely foods are GI "no-no’s – things like bananas, watermelon and nuts. Also, rigid adherence to the GI diet can cause bloating.

2. The South Beach diet

What it is:

A close relative of the GI diet, the South Beach diet permits "good carbs" like fruits, vegetables and whole grains and curtails "bad carbs" with high GI numbers like white flour or white sugar. It starts with a two-week period of very low carb intake, after which more whole-grain carbs are introduced.

How it measures up:

South Beach gets high marks for advocating whole grain carbs and for taking a hard line against saturated fats. But the overall carb allowance – especially during the phase-in period is too low for a healthy lifestyle eating pattern.

3. The Atkins diet

What it is:

The diet that launched a thousand diets, and drove bakeries and Italian restaurants to bankruptcy. Atkins is the king of the carbohydrate-restricted diets. Dieters go through three phases: a hard-core induction period with <20 g of carbohydrates per day, an increased weight loss phase of 20 g to 25 g carbohydrates per day and then a maintenance phase of 25 g to 90 g carbohydrates per day.

How it measures up:

Not at all. Particularly in the early phases, carbohydrate consumption is dangerously low, especially for people exercising an hour a day. Nutritionists have slammed the diet for being too high in fat. However, the Atkins diet can bring about rapid weight loss in people in whom other diets have repeatedly failed.

4. That French Woman’s diet

What it is:

The newcomer on the diet scene is burning up the best-seller lists. The diet is similar to the traditional Mediterranean diet of nuts, fruits and vegetables, olive oils, fish and beans – and even chocolate. It includes s "Miracle Leek Soup", recommended to the author after she put on 20 pounds in one year living in the United States.

How it measures up:

Like the USDA Guidelines, this diet is all about balance and portion size. Eat a little bit of everything. What nutritionists really like is the French attitude to food-eat because you are hungry, not because it’s there. But the alcohol allowance is typically French. A glass of wine or champagne every day goes beyond USDA’s definition of "moderate" – at least for women.

5. Weight Watchers

What it is:

A low- to moderate-fat diet that emphasizes portion control and calorie restriction by assigning a point value to foods. Weight Watchers bills itself as an approach to losing weight, not just a diet. It includes exercise plans, dietary books and weekly support meetings.

How it measures up:

Professionals like the Weight Watchers program saying it comes closest to the USDA Guidelines. No food is ruled out, but high-fat foods are granted only as small indulgences.