Many people believe any excess weight gained will be composed of fat created by eating too many calories and this is often true. But in fact, all weight gains are comprised of 3 components, fat, water and lean muscle weight and the factors leading to increased fat and water weight in particular (even lean muscle gain) vary.

As weight is gained all 3 components vary according to several factors; the most common include genetics, the personal energy level, diet quality and activity level, and environment.

If a persona has a predisposition to gain weight relatively easily, their personal energy is low (burn out), food energy intake is too high, physical activity is low and the time its taken to gain weight is over a longer term, as much as 90% of the excess weight will be made up of mostly extra fat stores. However, a small percentage of any gain will comprise lean weight and water.

When weight gain is short term, all other lifestyle factors aside; it's not just the food, it is the affect of the food that really makes the difference. This is a major diet trap.

For example, a gain in water weight is often due to an increased daily sodium intake.

Sodium in the body is mainly found in the fluids that surround the body's cells, such as the blood and lymph fluid. When sodium intake exceeds the amount the body can handle it builds up within the interstitial areas and the kidneys have to work extra hard to excrete a constant rise in daily sodium intake. A build up may cause the body to hold extra fluids in the blood and around the cells which contributes to increased blood pressure and also excess weight gain from water.
Daily sodium intake will always be high in the standard western diet.

The average diet in the western world is commonly made up of fast, packaged or convenient foods with long shelf life due in part to preservation affects of sodium. These typically nutrient poor foods, typically again, consist of high levels of salt and salt contains sodium. If a diet is mainly composed of high sodium foods then naturally the sodium intake also rises thus extra weight is gained quickly as the body holds onto water. It has been estimated that many people in the UK and USA may be carrying up to 5 pounds of extra weight due to the effects of a high sodium intake.

The opposite effect also happens when an individual reduces food intake in order to lose weight quickly. A percentage of the loss will be water because a reduction in high sodium foods means a reduction in daily sodium intake which results in water loss as the kidneys have a chance to finally rid the excess sodium from the body. This also helps partly explain why a dieter may experience the yo-yo effect when dieting, water weight is lost with food reduction or a temporary change in food quality, but quickly regains the weight when old eating habits are back to normal and daily sodium intake rises once more.

Here's the reality.

Just because you eat a food that has 200 calories for example, does not mean if you were overeating, you would gain .057 lbs of weight - 200/3500 calories (the amount of calories in a pound).

If that food is very high in sodium, and depending on how your body reacts, you could gain many pounds as your body holds excess water to keep the excess sodium away from negatively affecting the function of the cells. This throws many people off, particularly those who eat packaged diet foods, or unknowingly eat less of foods that are very high in sodium.

According to Joe Fuhrman M.D. we don't need more than 1000 mg of sodium per day, (which would probably increase if you were an athlete); basically, the amount of sodium you would get eating a 2000 calorie nutrient rich diet, full of nutrient rich foods that have natural sodium levels approx, 1/2 mg per calorie.

If you are eating a nutrient poor diet, and not eating for health, it's not uncommon to be eating foods that take your sodium intake upwards of 2000 - 3000 - 5000mg of sodium and that's is a formula for major weight gain, even if the excess calorie intake does not equal the amount of pounds gained.

It's not just the food and its calories, it's the quality of the food and it's affects on the function and performance of your body, that often determines weight gain and of course, your health.