It means that the more hours you sleep, the less time you can spend snacking. Most people sleep for eight hours a day. If you sleep for fifteen hours every day, then maybe you will eat less because you can't eat while you are sleeping. ---------------- In reality, this is a terrible idea. If you sleep all the time, your muscles will atrophy (waste away) and your metabolism will plummet (be reduced). In the end, your body will end up storing more calories as fat anyway, and you will look flabby (because you've lost all your muscle tone) and might gain weight. Don't do it! :-)

More clarification on "so the theory goes": In this case, "so the theory goes" is only unnecessary emphasis. You can replace it with such phrases as "So I've been told," or "people say," or "somebody told me." As I said, it doesn't really mean anything here. ---------------------- If you are interested in knowing what "theory" means in other cases, I will try to explain. There are two meanings. One is a scientific meaning, and one is used in casual conversation. They are similar, but not the same. A scientific theory is an idea or hypothesis that has been tested over and over again by many scientists. These tests have provided supporting evidence that the theory is correct. When used in casual conversation, the word theory just means any idea. Unlike when the word is used in a scientific sense, here it implies much less certainty. It even implies a little doubt. This is the usage that your original question employed. ----------------------- So, to review: You can mostly ignore "or so the theory goes" in your original question. It should not affect your comprehension of the sentence. When "theory" is used scientifically, it means something that is almost certainly true, like the theory of relativity, or the theory of gravity, or the theory of evolution. It is backed by A LOT of supporting evidence. When "theory" is used in casual conversation (and not discussing science), it means "idea," and it implies triviality.

Yes, I believe that you are correct: a person always weighs a little less in the morning. If you go to bed weighing, for example, 120 pounds, when you wake up in the morning, you will probably have lost about one pound or so.

I feel that I can think of very simple, do not eat before bedtime······╮(╯▽╰)╭