Q: How do we gain weight?
A: The classic equation for weight gain is:
Calories consumed – Calories burnt = Weight gained
However, this is an approximate model.
Q: Why do you say it is approximate?
There are a few unanswered questions with this model. For example- Why do some diabetics lose weight when they are consuming more calories than burning?
Another question is that why is it that even though most of us are consuming more than what we burn yet we do not keep gaining weight to infinity?
A related question: Why is it that some of us settle on higher stable weight while others on a much leaner stable weight?
Q: I now see that the weight gain model needs refinement. Can you elaborate?
A: The first refinement is to understand that we are not concerned with calories consumed but by the calories absorbed.
There is a crucial difference. We do not necessarily absorb every calorie we consume. We also expel unabsorbed calories as waste.
In addition, we do not burn any calories directly. Biology is involved. The calories have to be absorbed by the cell first before they can use it. The calories burnt by a cell may come from the calorie absorbed from the food we just ate or it may come from the calorie stored in it.
The key for weight loss is to ensure that the calorie we use comes from stored calorie. This happens when the calories burnt is greater than the calories absorbed from the food we ate. The weight loss equation now becomes:
Calories Absorbed- Calories Burnt = Weight Loss
Q: Let us break it down. The first question then becomes what is the mechanism for absorbing calorie?
A: The key hormone for calorie intake by cells is Insulin.
Every cell in our body has insulin receptors on its surface. When Insulin molecule sits on the receptor, it is a signal for the cell to begin accepting calories. Under normal conditions when calories in the form of glucose is circulating in the blood, Insulin accompanies it. The Insulin signals the cells to absorb the available calories.
However if glucose is available in the bloodstream and Insulin is absent, the cells will be unable to absorb it and may even starve to death even though it is freely available so close by in the blood stream.
Think of Insulin as a key to the door of cells. Until the key is not present, the door cannot open and cells cannot absorb calories.
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