If you want to gain weight, you must eat more and if you want to reduce weight, you should eat less and spend more.
Is it really that easy?
Those who would like to achieve a desired weight, are often wondering how many calories they need to spend and how many they need to intake. Many times they believe that the change in body weight depends only on caloric intake and expenditure. So, if you would like to gain weight, you should eat more than you spend, and vice versa, if you want to reduce it.
Unfortunately it is not that simple.
Calories are just a measure of potential energy that the body is not using in the way you want. The energy, which is obtained from food and then spent, it’s affected by a lot of factors. In fact, it depends on how the food was grown and processed, how your hormones and digestion act, how old you are, whether you are active, etc… Therefore, you can never know for sure what goes in and what comes out.
EXAMPLE OF WEIGHT REDUCTION
(…pay attention that here we do not take into account factors that affect caloric changes and we focus only on the numbers).
According to recommendations about healthy weight loss, you can lose about a pound of fat mass per week. Assuming that 1 g of fat has 9 calories, you can quickly figure out that you have to spend additional 4,500 calories a week to lose a pound of fat. If you again assume that 1 g of carbohydrate means 4 calories, you can see that 1.125 g of carbohydrate has the same caloric value as a pound of fat. As a consequence, you need to give up 160 g of carbohydrate daily. If you have 4 meals a day, that means 40 g less per meal (for example, two pieces of bread are approximately 40 g).
But, since you already know that theory and practice are often separated between themselves and that with diet alone you cannot effectively lose fat mass, you should rather try the practice.
So, if you want to achieve or maintain your optimal body weight, just adjust your lifestyle to this purpose. It is clear that no objective can be achieved without proper nutrition and adequate activity.