Calories vs. Fat/Carb content

Question
Laurie,

Thank you for your time!  I've read that regardless of whether a food contains
mostly fat, mostly carbohydrates, or protein, eating too much (too many
calories) will result in a gain in fat.  This is confusing to me, because that
would imply that only calories matter in whether a person maintains or loses
weight.

That would also mean that if a person ate 500 extra calories of chicken per
day, or 500 extra calories of cake, they would both gain a pound of fat after 7
days.  In reality, wouldn't the cake cause much faster gains in fat?  How is this
reconciled with the idea of "anything extra" going to fat?

Thank you so much!

-Brian

Answer
Hi Brian,

Yes, calories are the only thing that matters when it comes to weight gain (or loss). Let me see if I can explain:

Calories in food are a measure of potential energy. If we eat, we have calories to burn and can run our body's machine, as well as do other activities (about 2/3 of the calories are used just for daily functioning--heart beating, kidneys working, lungs breathing, etc). If we don't use all the calories, we store them as fat.

Biochemically, the body breaks all food down into molecules of carbon atoms, waiting to be either used or stored. After a while in the body the compound we ate is no longer in the form of dietary fat or carb or protein--it's in glycogen (stored energy in muscle tissue) or glucose (for cells to use as energy) or fat that our body stores for long-term use.

It's a way we have of adapting for the survival of our species--if no fat is around we can live off chicken, if no meat is around we can live off fruit, etc. Over time, of course, a person would suffer various vitamin and mineral deficiencies, but you won't starve to death for as long as you have any food to eat because we can use the potential energy in any food for the energy our body needs!

The conception some people have that "I can eat all the (fill-in-the-blank) I want because it's good for me" is what keeps some people overweight although they insist they are only eating healthy foods. While you can quickly eat "too much" cake, you can also eat too much fruit or too much fish, even though in moderate amounts these are certainly good for you.

Feel free to write back for clarifications. I hope I've cleared this mud up a bit for you!

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