The weightloss industry is a booming one. The surge of obesity and overweight along with the associated morbidity and mortality has led to increasing research and a flurry of marketing of various diet plans aimed at weight-loss. An estimated 50 million Americans go on weight-loss diets and spend $30 billion for diet programs and products every year. How much do we know about the long-term health effects of the various weight-loss programs?

A recent study compared the effectiveness and safety of eight currently popular weight-loss diets-2 Weight Watchers plans, Atkins, Ornish, The Zone, South Beach, New Glucose Revolution, and the 2005 US Department of Agriculture Food Guide Pyramid-and gave the best health rating to the Dean Ornish plan: a low-fat, high-fiber, vegetarian diet that is also a pioneer at reversing heart disease.

The largest commercial weight-loss plan-Weight Watchers assigns points to various foods based on the fat, calorie and fiber content. Foods rich in fiber are assigned a lower number than foods high in fat and calories. The idea of dieters is to try and maintain their total score below a targeted value based on their current weight and desired weight loss. The two plans included are a high-carbohydrate plan and a high-protein plan.

Atkins' diet is high in fat and a low-carb diet that accommodates for carbohydrate allowances in four phases and aims to achieve weight loss initially and weight maintenance in the long run.

The Dean Ornish plan was designed by Dr Dean Ornish, an MD, with an idea to formulate a meal plan for his patients with heart disease and has been very popular amongst doctors advocating dietary regimes aimed at arresting the growing burden of obesity. It is basically a vegetarian diet that emphasizes foods high in fiber and complex carbohydrates, limits fat intake to no more than 10% of a day's calories, and strictly limits cholesterol and saturated fats.

The Zone Diet plan is reduced in calories and carbohydrates and specifies the proportion of daily calories from from carbohydrates (40%), protein (30%), and fat (30%).

South Beach Diet plan, which is followed in 3 phases, begins with a reduced-carbohydrate phase and gradually settles into a plan that includes modest amounts of whole grains.

The New Glucose Revolution consists of a finely balanced lean proteins, healthy fats, and high-fiber complex carbohydrates with a low Glycaemic index. The Glycaemic index measures the level by which foods increase the blood Glucose values. Higher the index more the risk for obesity and related illnesses.

The Food Guide Pyramid plan recommends the volume or weight of foods such as fruits, vegetables, whole grains, meats, and low-fat or nonfat dairy products that should be included in the diet each day. The plan is driven by common knowledge of the various nutrients and foods that prevent chronic disease and nutrient deficiencies. In simple terms it is based on the age-old food pyramid taught to us in schools!

The fats essentially considered healthy-PUFA and MUFA (Polyunsaturated and Monounsaturated) and derived from plant sources are generally recommended in all these weight plans. These fats can also be derived from fish oils which are conventionally called as Omega-3 fatty acids. The only variant is the Atkins' Plan which does not restrict the "Unhealthy Saturated Fats".

How was each plan assessed? The Alternate Healthy Eating Index (AHEI) was used to measure a diet's cardiac-risk reducing effect. This was based on several quality parameters such as the amount of fruit, soy, nut, vegetable, and cereal fiber, the ratio of white to red meat, the ratio of polyunsaturated to saturated fat, and the amount of trans fat (which are unhealthful partially hydrogenated oils).

In order of scores, the Ornish plan came out first followed by the Weight Watchers and New Glucose plans. The reason for the rankings was that these plans all had high scores for being greater in their cereal fiber, vegetables, and fruits content, and low in trans fats. The Atkins' Plan was the last on the rung due to its greater imbalance in white-to-red-meat ratio, polyunsaturated-to-saturated-fat ratio, and cereal fiber and trans-fat content.

According to researchers who studied these plans in detail, patients and their healthcare providers must be conscious of health concerns, especially long-term health concerns when choosing a plan for weight loss because dietary change is meant to be a long-term process.

While short-term weight loss is possible with any of these diets, in obesity management long-term weight maintenance and lower heart disease risk is crucial. The conclusion is that weight-loss plans that best handle these long-term issues are the ones which are high in fiber-dense complex carbohydrates.