If you plan on losing weight for 2002, you may be thinking about trying one of the newly popular diet programs that are out there, such as The Zone. But before you sign on, you may want to know what Canada AM's nutrition consultant Leslie Beck says about the pros and cons of the plans.

A diet program that's grown popular in recent years is Dr. Atkins' New Diet Revolution and its cousin, The Protein Power Plan. These diets are high in protein and fat, and very low in carbohydrates. They allow only 30 grams of carbs -- about 1.5 slices of bread -- no fruit, no dairy, no sweet vegetables and no sweets.

"There's no fibre, there's no calcium, there's no vitamin D, C, or most of the B vitamins," Beck says.

The diet's concept is that it will promote ketosis, a metabolic state that occurs when the body burns fat because it has no carbohydrates to burn. Beck says ketosis is an abnormal state for the body to be in and can be dangerous in the long term. It's a powerful diuretic that will cause the body to lose lots of fluid, including lots of minerals and electrolytes. That can be extremely dangerous for anyone with kidney problems.

The diet may appear to work initially but eventually most people will crave carbohydrates and fall off the plan, quickly regaining any weight they lost.

"High protein diets are not healthy overall," says Beck. "It's not a healthy approach to losing weight and keeping it off. At very best, it's a short term fix."

Another diet that's similar to the Atkins diet is The Zone by Barry Sears. It calls for a 40 per cent of calories to come from carbohydrates, 30 per cent protein, and 30 per cent fat. While it's relatively high protein, there are enough carbs to prevent ketosis.

Sears claims that the diet promotes the balance of two blood hormones: insulin and glycogen. With less insulin in your blood, Sears claims, your body will burn fat stores, causing you to lose weight.

"It's the healthiest of the bunch," Beck says, noting that it includes plenty of protein along with fruits and vegetables.

But she adds that Sears's claims about blood hormones have never been proven. And, she notes, that the diet lacks enough calcium, vitamin C and A, and because of its emphasis on insulin and glycogen, can be quite confusing for some dieters.

She says the main reason the diet has worked for some is that it's simply low calorie: about 1,200 to 1,800 calories, depending on your gender.

The third diet is the Carbohydrate Addict's Diet by Richard and Rachel Heller. the authors claim that if you crave starches and sweets you're "addicted" to carbohydrates. They claim that as many as 75 per cent of overweight people have the addiction.

The authors say that eating too many carbs will cause too much insulin to enter the blood. This high insulin level will interfere with the usual rise in seratonin in the brain hat signals the eater that they're satisfied. But in carb addicts, the authors say, something malfunctions and not enough seratonin is produced in the brain. As a result, the eater keeps eating.

The diet reduces intake of carbohydrates to reduce cravings and correct the excessive release of insulin that makes the "addict's" brain malfunction. It allows carbs at only one meal a day -- the Reward Meal, it calls it.

Again, Beck says the diet is low in calcium, vitamin C and A and fibre. And she notes, that again, the theory about excessive insulin affecting seratonin has never been proven. by any other respected sources.

Beck concludes that the reason any of the diets work is that they reduce calories. But their low levels of key vitamins will eventually cause long-term problems for the dieters. And the constant worry about balancing carbs and proteins makes the diets doomed to fail, as dieters become overwhelmed with the complicated counting.

Beck says the best way to lose weight is what's it's always been: make permanent changes to you diet to include more fruits and vegetables, and cut down on the fat.

"Forget about fad diets and quick fixes," Beck says. "You've got think permanent, long-term changes. Everything you do to lose weight has to be everything you do to keep it off."

She also recommends keeping a food diary so you have a firm idea how much you're really eating and find ways to make changes.