The battle of the bulge has long been woman's and man's most frustrating hurdle in health and self-image improvement. Like the Freudian mandate that our personality disorders may have causes other than ourselves, the new research now indicates that obesity may not be entirely due to gluttony and lethargy, as stereotypically believed. We know it too well, to great disappointment of many, that some people put on weight more easily and quickly than others, regardless of diet. It had long been believed that by cutting down on calories and exercising more, we can lose weight. But now we find that most people tend to fluctuate around a "set point" weight throughout their adulthood as a result of genetics and the feeding habits in early childhood. When this weight is disturbed through under or overfeeding, physiological and psychological changes occur in the body that resist this change.

Environment and social conditions do make a difference. But people are affected differently through the body's internal regulation system which comprises an intricate working between the brain's "feeding centres" and "satiety centres." The connection take place through chemical messengers, mainly hormones and endorphins found not only in the brain but also in the stomach and intestine. Many foods also contain or release these hormones. One such hormone now closely involved in this weight cycle is called insulin which is released in the body when we consume foods that elevate glucose levels in the blood. (In diabetics, the release of insulin is reduced, causing sharp rises in blood sugar levels with severe implications including death.)

The new research indicates that insulin does a lot more than just moderate blood sugar. Insulin also binds to brain cells to increase our desire to eat more. Therefore, the hunger pangs resulting from low levels of glucose in the blood do not diminish if the food we are eating causes insulin shoot-up. A sharp insulin increase because of quick enhancement in blood glucose also causes quick and efficient conversion of excess body calories into fat cells. In the absence of such high insulin levels, the conversion process is not very efficient., consuming about 30 calories to convert 100 calories into fat. In the presence of insulin, it takes only 4 calories. Additionally, persistent presence of high insulin in the blood also increases cholesterol and triglyceride levels, the two factors mostly held responsible for blocked arteries and heart attacks and strokes.

These new findings go a long way in explaining why we should plan our diets to yield smallest frequent rises in blood insulin. Keeping blood insulin levels low is a good way to reduce our body weight without the hazards of strenuous dieting. Given the same number of calories, some people will put on weight while others may not. If the same number of calories produce high insulin response, conversion to fat is increased and we put on weight. We must therefore strive to select food combinations that, while giving us essential calories and nutrients, produce a flatter insulin response--what we call in medical jargon, the low glycemic index foods.

The foods we eat are of three types: carbohydrates, proteins and fats. All of these foods provide calories but the amount of calories and how soon they are digested and absorbed are quite different. Both carbohydrates and proteins have about 4 calories per gram but fats have 9 calories per gram. Carbohydrates are more easily digested and absorbed than proteins and fats are absorbed at the slowest rate. There are two reasons for this: first, carbohydrates pass through stomach very fast whereas proteins and fats delay the emptying of stomach contents into intestine, from where the foods are absorbed; second, the digestion process of carbohydrates is much simpler than for protein and fats which are broken down by very slow chemical reactions. As a result, carbohydrates have the highest glycemic index followed by proteins and fats. So, from the point of view of glycemic index, some carbohydrates do not fare well. But there is more to the value of food than just glycemic index. Fats have the lowest glycemic index but they can wreck havoc in the body by blocking arteries. Carbohydrates remain the best food except that we should know which ones we should avoid.

The glycemic response of carbohydrates is of great interest to us. The highest glycemic response (the 100% response) occurs when we consume glucose (the simplest carbohydrate) directly. All other foods are rated in comparison to a dose of glucose. The rise in blood sugar after two hours of ingesting a food is measured comparing it to the response that occurs after a dose of glucose. Carbohydrates that are slowly digested such as complex carbohydrates (pastas and breads, etc.) have long been identified with healthier diets--now we know why. Also, foods that form a gelatinous mass in the stomach or retard digestion of food (since they contain chemicals that inactivates digestive enzymes), such as gums, pectins, legumes, etc., are slowly digested and absorbed. These foods also reduce the glycemic response of the other foods eaten after their ingestion. Given the large number of variations in the food combinations and the variability of individuals in digesting them, it is not always possible to predict which foods will be consistently absorbed slowly. But we can draw conclusions regarding the selection and combinations of foods that will provide "good" calories and the least glycemic response.

These new findings explain why given the same number of calories, some people will put on weight while others may not. If the same number of calories produce high insulin response, conversion to fat is increased. We must, therefore, strive to select food combinations that, while giving us essential calories and nutrients, reduce the insulin-release response. Food combinations can make much difference in glycemic response. Foods rich in enzymes that break down or digest carbohydrates will increase glycemic response. The race is now on in drug development to find drugs that will slow down digestion of carbohydrates. Slow absorption of food has another advantage of wasting of calories since the food may pass across the best areas from where the calories are most efficiently absorbed.

We can begin our healthy diet by first selecting foods that have low glycemic index. And that's where we find many surprises (see chart). Whereas most of carbohydrates fall in the top 50% of glycemic response index, the variation is large and there are "good" and "bad" carbohydrates. For example, fruit sugar is much better than regular sugar and of course if you take glucose it will give you the highest index. The high glycemic index foods will increase appetite, increase absorption and speed up deposition of fats from calories obtained from the rest of the food as well. The old habit of consuming bread or potato with high protein and fat diets (popular in many Pakistani and Western diets), such as qorma and nan will make the qorma a lot more fattening. The type of bread is used is also important. For long it was thought that whole-meal breads are better because they provide fiber but now we know that the "brown" stuff is more than just fiber; it likely contains chemicals that slow down digestion process. However, when we compare the glycemic response, we find brown bread to be slightly worse than white bread in terms of its glycemic response. This is because the high content of fibre in brown bread causes it to pass through stomach quickly into intestine where it is digested. The small difference in the glycemic index however does not make brown bread less useful since the main utility of whole-wheat breads comes from their fibre content.

Surprisingly, carrots have very high glycemic index comparable to honey and potato. Since fats are always slowly absorbed, such as butter, there is a blessing in disguise in the case of the fatty foods we take. However, the extremely large caloric portions that these foods bring always overwhelms the advantages of their slow absorption.

What remains and comes out repeatedly, the best foods to consume are good old lentils and fruit.

This theory has recently been exploited in Michel Montignac's books with such titillating titles as "I Eat, Therefore, I Slim Down," "Dine out and Lose Weight," and "Eat Yourself Slim." Time Magazine did a story on how Montignac's affair with food is fast spreading throughout the World. The bottom-line is that we should use more complex carbohydrates and avoid combinations of carbohydrates with fatty meals if we want to reduce weight. No we know why some people put on more weight than others; among several reasons, one likely reason is the wrong combination of foods and that's something we can easily alter.