Good carbs, bad carbs

The Atkins Diet
The regime You start on 14 days of a very strict diet that forces your body to use its fat reserves. You eat all the protein and fat you want and less than 20 grams of carbohydrates a day from salad or cooked vegetables. After that, Dr. Robert Atkins suggests you stay on a high-protein diet for life and eat as much (or as little) carbohydrate as you can tolerate without putting on pounds.

What they got right—and wrong One study published last year in the American Journal of Medicine found that good cholesterol levels actually went up and bad ones went down in people who were on the diet for six months. Still, it's just one study, and Janna Pinchuk, a clinical dietitian at Sunnybrook and Women's College Health Sciences Centre in Toronto, worries about the fat and cholesterol content of the diet. Most importantly, "There's no fibre in meat. When we avoid fibre we get constipated and feel terrible," she says.

Carbohydrate Addicts Diet
The regime This maze-like diet starts you on two weeks of eating protein and very low GI veggies twice a day with an eat-anything-you-want reward meal once a day. In theory, eating no carbs twice a day will suppress your insulin levels at the third meal. From there, you can pick one of four ongoing diet plans, depending on how much weight you want to lose in total.

What they got right—and wrong It is possible to trick your body's insulin response by eating low-carb for two meals each day. And having a reward meal can cure you of carb cravings. But you're still limiting your nutritional choices.

Sugar Busters
The regime On this 14-day plan, all sugars and high-GI foods such as potatoes, carrots and white bread are strictly forbidden. You have a few high-fibre grains, but mainly you're eating proteins, fats, vegetables and certain fruits. The doctors who invented this diet denounce the idea of counting calories as well.

What they got right—and wrong This diet gets kudos for being easy to follow and recommending you eat fibre-rich whole grains. But it's way off when it suggests calories don't matter.

The Zone
The regime A doozy to figure out, Hollywood's darling Zone diet suggests you eat 40 per cent carbs, 30 per cent protein and 30 per cent fat at every meal. Which carbs, fats and proteins? That depends on which "block" you fit into (you've got to look this up on a chart). The Zone's strict complicated rules are particularly suited to those who can afford to get all their meals prepared and delivered (at $35 to $45 a meal, this pricey service is available in Toronto, as well as Beverly Hills).

What they got right—and wrong While the Zone takes a great deal of planning to follow, "People like it because it's very prescriptive. It tells you what to do and takes away that decision-making," says Glanville. Other experts note it's also fairly balanced nutrition-wise, but they still suggest that lower-carb eating is the way to go, not avoiding carbs altogether.