Its not the quantity but the quality of calories that makes a difference.
Low calorie regimes lead to the paradox that the less we eat, the more our survival instinct drives our bodies to lay down fat reserves for fear of malnutrition. Calorie intake has nothing to do with fat storage. Hence, the quantity of calories consumed don't make a difference, the quality does. For instance, the carbohydrate from a potato does not metabolise (break down) the same way in the body as carbohydrate from lentils (pulses).
A recent research led to the startling discovery that the key factor in weight gain or loss was the metabolism of carbohydrates in the body by insulin. So, just as there are good cholesterol (polyunsaturated fatty acids - sunflower oil, safflower oil, sesame seed oil, soya bean oil) and bad cholesterol (saturated and monounsaturated fatty acids - coconut oil, ghee, dalda, vanaspathy, palm oil, mustard oil, groundnut oil), there are good and bad carbohydrates too.
All carbohydrates have a glycemic (sugar) index which is the rate at which they are metabolized by the body into sugar. High glycemic foods considered to be bad carbohydrates are - refined white sugar, refined flour, white rice, white bread, semolina, potatoes (all varieties) and cooked carrots. Normally, the ingested foods rich in carbohydrates (other than those just mentioned above) are converted to glucose, fructose and galactose in the stomach and the intestines. It then passes to the liver, where a greater part of the glucose and the entire fructose and galactose are converted into glycogen. Liver acts as a storage of glycogen.
Now, during the body's requirement of energy, this glycogen from the liver is transported to the body muscles, cells and tissues by the blood. Then, through the process of glycolysis, occuring in the muscular tissues, the glycogen breaks down to lactic acid which serves as the body's energy. If excess of energy is produced, i.e. more than the body's requirement, it is stored as fat in the adipose tissue. This is the body's normal metabolism of carbohydrates. Now the glucose which is not converted to glycogen, is carried to the blood and stored as blood glucose in normal levels. When the blood glucose is high (due to consumption of high quantity of carbohydrate foods), muscles and tissues withdraw the glucose, convert and store it as glycogen or depot fat, thus reducing the blood glucose. This depot fat is stored in the adipose tissue finally leading to overweight/obesity.
Ingested carbohydrate foods with a high glycemic index are not entirely converted to glucose. These escape conversion of glucose to glycogen in the liver. This glucose which cannot be stored in the liver, is thrown into the blood stream. Since this excess glucose in the blood is not required for the production of body energy, it prompts the pancreas to produce insulin. Insulin is the strongest hormone for lowering the blood sugar. Now the resulting drop in blood sugar, caused by the insulin, not only causes faintness, fatigue and mood swings but conversely leads to more craving for food. This finally causes more intake of food giving rise to overweight and obesity problems. It also prompts the body to store fat as body fat.
Too much insulin or hyperinsulinism is another medical explanation why some people are overweight and others are not, even though they are consuming carbohydrate food of the same quantity. The reason supports the explanation that consuming high glycemic carbohydrate food, increases insulin secretion which lowers blood sugar and increases craving for food. This increases the body weight causing super obesity.
By contrast, foods with low glycemic content - lentils, cereals, whole wheat bread, whole wheat flour, brown rice, brown sugar, soya and soya products, raw carrots and most fruits and vegetables are metabolized slowly by the body as glucose to glycogen and stored in the liver and muscles. This glycogen doesn't go into the body's storehouse of fat. As and only when the body requires energy, this glycogen is released to form energy.
It is believed that Indian diet is far too rich in saturated fat and sugar which is why the upper and middle class (and their children) suffer from excess weight problem. Whereas, the traditional Indian diet, which is rich in lentils and vegetables, are generally consumed by the lower middle class and the poor but is far superior. Even buttermilk in which the milk fat has been fermented/removed as in yoghurt, is non-fattening.
Thus the Green Revolution, has been bad in nutritional terms. The diet regimes usually collapse in practice from an unappetizing rigidity of rules. So it is high time that we think and act as how to lead ourselves towards a better and healthy lifestyle. The quality of food matters more than the quantity. This should be a rigid rule for all mankind. Applying this in everyday living only will Green Revolution find its benefit, making the food more appetizing from a nutritive viewpoint.