There has been some recent research that indicates that
combinations of fat cause a feeling of fullness that causes a person to
no longer desire to eat.
Many believe that weight gain and loss is solely related to calories in versus calories out. Others say that the type of food eaten determines the metabolic path that it follows and greatly influences whether it is stored as fat or flushed through the system. No one has actually ever answered the question of whether every calorie consumed is either utilized or stored. Perhaps this a genetic characteristic and is very individual.
Regardless, it is clear, that for a given person, if they reduce calories, they will retain less weight than at a higher calories load. This is simple physics. Retained energy as fat cannot exceed energy input minus energy utilized. Retained energy could be less if the excess if flushed, but I know of no validated research in this area.
There is a very strong negative link between saturated fat, trans fatty acids and coronary health. While fat is necessary for life, saturated fat is not, nor are trans fatty acids. It would be prudent to avoid them as much as possible. Red meat and hydrogenated oils, found in many products, are primary sources of these compounds. You may consider them the "bad guys."
A diet that severely restricts carbohydrates or fat, protein should never be severely restricted - it is necessary to life, has been shown to cause an initial weight loss. Keeping the weight off, then, becomes the big problem. One thing that is incredibly unwise and counter productive is severe calorie restriction. When calories are restricted, the body goes in to a "starvation reflex" and the metabolic rate slows, making weight loss even more difficult. Continued restriction is said to cause the wall of the fat molecule to alter from a type "A" composition to a type "B" composition, which is much more resistant to metabolization. Bottom line: dieting, long term, will probably make you fatter and it will definitely make it more difficult to lose weight.
I have successfully lost weight on various rather healthy diets, but the most dramatic changes to my body were brought about by a carb restriction and then loading routine, coupled with an exercise routine. On that routine, I lost body fat and gained muscle. The combination of the two produced excellent results.
Losing weight is not all that difficult. Not finding it again is the really hard part. There is a phenomena call the "set point," where the body seems to try to maintain a certain weight. There have been discovered biochemical interactions that seem to support this theory. At this time, there is no simple way to modify the set point, but experience has shown techniques that seem to modify it.
One is exercise, another is the gaining of lean muscle, and another seems to be periodic short fasts - not enough to stimulate the starvation reflex. Another may be long term consistent calorie consumption for the target weight - long enough for a deviation to cause the "set point" response to take place.
Short term calorie restriction alone, will not, cannot alter the set point. Severe calorie restriction, of course, causes all of the problems mentioned earlier. Coupling a weight loss diet with exercise does cause fat loss an muscle gain, a combination that consistent with set point alteration. Once the target weight is reached, normalizing the diet is possible. A slow shift is made towards a less restrictive diet regimen, while maintaining a healthy level of exercise. Care must be taken to not rebound into bad habits, but since you've been eating in a responsible manner, probably for several months, that is not really that difficult.
The battle is won. The war is not over, but the battle is won and you have the tools to control this aspect of your life.
You did it!