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"Want to lose 20 pounds in six weeks? Click here to start," the advertisements declare, promising miraculous weight loss. Surfing the net it is quite common to see such eye-catching dialogue boxes pop up, the latest being the Glycaemic Impact Diet (GI Diet) that is considered Europe's hottest diet. Yet how effective is it?

A specialist in Nutrition and Dietetics, Dr. Damayanthi Perera vouches for the efficacy of this method, which is based on a meal plan with an accent on non-expensive, traditional foods. "It empowers people to look after themselves by making lifestyle modifications," she explains.

Those discouraged by the western menus recommended on the internet meal plan can take heart as according to Dr. Perera you can incorporate the diet plan easily with Sri Lankan menus. Yet, it is a complicated system that one needs to understand properly to apply scientifically.

The GI diet or the Sugar Index Diet it would seem is highly effective for those suffering from non-communicable diseases (NCD) such as diabetes, heart disease and cholesterol as also for weight loss. However, she recommends that it be followed under the supervision of a qualified nutritionist.

How did the GI diet originate? It was in the 1980s that Canadian researchers studying the conventional diabetic diet realised that their theory that simple carbohydrates (glucose, lactose, etc.) are more easily absorbed by the system than complex carbohydrates (starch, bread, potato) was proved incorrect.

Their discovery that not all simple carbohydrates are absorbed faster than the complex, led them to categorise carbohydrates into good and bad. It was thus concluded that carbohydrates with high glycaemic impact/index were the bad carbs and those with low glycaemic impact/index were the good carbs. The GI Diet materialised from the exercise.

Under this premise, glucose has a lower glycaemic impact than potatoes contrary to common belief. Similarly it went on to prove red rice has the same GI as white rice, though the former contains more fibre. Hence the good news for diabetes patients is that they need not take red rice if they do not prefer to do so as our local food is in any case rich in fibre. However, a combination of low and high GI foods will need to be integrated for sports nutrition to enhance performance.

It is important to notethat a number of factors affect the measurement of GI or sugar index - the type of fibre, acidity, particle size, etc. However, the colour of rice does not determine the GI. This theory certainly calls for people to take a new look at foods and make informed choices. A nutritionist can teach how to balance various foods to ensure a balanced diet.

Further, one can no longer assume that equal portions of carbohydrates give a similar increase in blood sugar. It is now known that the bodily response of different carbohydrates varies according to the GI of the foods.

That said, it is important for those initiating the diet plan to know the GI of different foods. GI Research has to date analysed over 600 food items including several ethnic foods.

The clinically tested GI diet is considered effective for weight loss, lipids and ensuring a feel good factor as it improves metabolic efficiency. "It is certainly an answer to the prevention of NCDs," Dr. Perera explains. Best of all, for individuals following the diet, it takes away the guilt of eating and enjoying food. By balancing GI foods, one does not need to deprive oneself.

Compared to other diets, GI Diet is one of the healthiest weight loss options, especially if you stick to it, the nutritionist says. Interestingly, as one eats more of low GI foods that normally get absorbed slower, a person is assured of higher energy levels and lower food cravings.

A GI meal plan today is considered as a positive diet because of the choice of foods it allows. Further, separate cooking will not be required as the whole family can benefit from it. At the Nutri Life centre Dr. Perera runs, she has seen how effective the anti-ageing diet can be.

How soon can you see results? "It is certainly not any magical formula," Dr. Perera cautions. Although results vary among people, ideally a person can lose about one kg a week, 5 in a month and 10 in about 3 months. Nevertheless she recommends that the diet be teamed along with exercise and stress management to be effective.

Suddenly, the latest health craze seems to be all about carbs. You can't open a magazine or newspaper, turn on the television or walk into a grocery store without encountering "low-carb" claims. First, the Atkins Diet extolling the virtues of low -carb diets while dangling the promise of eating unlimited amounts of fats and proteins, then others like the Zone Diet and the South Beach Diet which emphasise eating "good" carbs and eliminating "bad" carbs, now advice turns to the glycaemic index of carbs. Should you be jumping on the carb bandwagon? Here’s a look at the latest scientific understanding of carbohydrates and their role in a healthy diet…

Carb Classics
First of all, what are carbs (or carbohydrates) and what do they do?

Carbohydrates are one of the three macro-nutrients (fat and protein are the other two) that we get most of our energy (measured in Kcalories or Kjoules) from. Examples of carbohydrates are sugars (as in table sugar as well as those found in fruit and grains) and starches (found in rice, wheat and cereal products like bread). Some carbohydrate containing foods such as whole grains, fruits and vegetables also contain dietary fibre which plays an important part in our health. The human body cannot digest fibre and hence fibre does not contribute any energy to the diet - but it does reduce the risk of weight gain, heart disease and bowel cancer. Most health authorities recommend consuming at least 25-30g of fibre in the diet and this amount is easily obtained by eating moderate amounts of carbohydrate containing foods in the form of whole grains, legumes, fruits and vegetables.

Varying amounts of simple (such as sugars) and complex (such as those containing starch) carbohydrates are naturally present in fruits, vegetables, grain foods and many dairy products. Carbohydrates may also be added into processed foods for example as thickeners for gravies and sauces.

Carb quality
In addition to this classification of carbohydrates into simple and complex, more recently there has been a great deal of interest in understanding the impact of dietary carbohydrates on glucose levels in the blood. The glycaemic index is a classification system based on the ranking of carbohydrates, according to their immediate effect on blood sugar levels. Foods with a high glycaemic index (GI) increase blood sugar quickly after consumption; and those with a lower GI break down more slowly and have a more gradual and sustained effect on blood sugar. Foods with little or no carbohydrates (like meats and eggs) have no GI.

Researchers have been investigating how GI may play a role in the body's sensitivity to the hormone insulin and the production of other hormones which are involved in the regulation of appetite, blood fats and blood sugars. For example, foods with a low GI result in lower insulin levels overall, and enable people to feel full longer, delaying the return of appetite after a meal. The lower levels of insulin also result in lower levels of fats, such as cholesterol and triglycerides in the blood.

Promisingly, several large-scale epidemiological studies have shown an association between a low GI diet and a lower risk of Type 2 diabetes. While the reasons for the association are still not fully understood there is a growing body of evidence that those with or at high risk of developing Type 2 diabetes may benefit from a low GI diet.

However there are a number of critics of the glycaemic index, in particular some health professionals believe GI may be too cumbersome to be a reliable tool as a dietary guide for consumers. For example, the GI values of individual foods are not good indicators of the impact these foods will have on blood glucose when consumed together. As most foods are consumed with a variety of other foods in meals and snacks, this information would be more useful than the individual food GI values but it's clearly not feasible to determine Gls of all possible meal combinations. Also, the GI of a food differs slightly between individuals and can also be affected by how the food is cooked, the plant variety and method of growing. Take apples for example: According to the University of Sydney's GI website, apples from Denmark were found to have a GI of 28 and the GI value of those from the United States was 40.

Curbing carbs to cut weight?
Studies have shown that generally, people on low - carb diets do lose weight in the short term. In addition, after being on the low-carb diet for six months, study participants have better blood triglyceride levels, increased levels of 'good" cholesterol and better blood sugar control.

However researchers attribute the gains to actual weight loss rather than the reduction in carbs. Generally any diet that limits the amount of carbs one is allowed to eat will also reduce total calories consumed. Hence people on low - carb diets usually eat less total calories than they regularly do Many researchers believe that the same results can be achieved by reducing the total amount of food consumed, irrespective of food group included of excluded.

A study conducted by Dr Michael Dansinger, of Tufts-New England Medical Center, Boston published in the Journal of the American Medical Association showed that people lost weight on any diet - the length of time they stayed on a diet, not the type of diet - determined how much weight they lost. Also, the gains in blood triglyceride levels, cholesterol and blood sugar were seen in all diets whether they were low-carb, low fat or just calorie controlled.

Furthermore some researchers point out that low-carb diets that are usually high in protein and fats may exert an unusual burden on the kidneys. Hence they may not be suitable for some one who is diagnosed with a kidney problem or equally importantly, anyone who may not be aware that they have kidney problems. Diets high in saturated fats and cholesterol may also increase the risk of heart disease and some forms of cancer in the long - term.

Nevertheless all the focus on carbs has at least highlighted that not all carbs are created equal. If there is a lesson from the carb-craze, it is that optimal diets should feature whole grains, fruits and vegetables and be low in sweets, desserts, pastries and products made from refined white flour.

Indeed recent studies are beginning to indicate that a diet based on moderate amount of carbs (comprising mainly whole grains, fruits and vegetables), lean protein (fish, lean poultry and beans) and low in fat may be the best mix for weight management and the prevention of chronic diseases like Type ll diabetes and heart disease.