I received a few good questions from Kathleen a little while back and finally have time to respond. Let me preface this with "you don't learn much about nutrition and weight loss in medical school", so a lot of readers can, I'm sure, add their expertise.
I've been trying to research exercise and weight after I stopped running so much and dropped 7 pounds in 2 weeks?!!
It is common to lose weight when you stop exercising because you lose muscle and you also lose the fluid/inflammation which collects around the muscles. My guess would be that the average woman who exercises daily and stops exercising would lose about 5 lbs after two weeks. But that is just an estimate.
I don't know if I believe the old adage of calories in calories out. It assumes all calories are equal. While yes, 1 calorie from any type of food contains the energy needed to raise 1 gram of water 1 degree. Calories aren't processed by the body the same. So, far, out of all the research people have done on obesity and exercise. I can't find conclusive evidence that exercise will keep the pounds off.
I still say calories are calories. Some make you fuller than others. Some of you may think, well, what about the Atikins Diet? Huh? This puts the body into a crisis mode where you have to convert your fats into ketones. And this in itself causes the burning of more calories. So it causes weight loss but doesn't break the rule of a calorie is a calorie.
And exercise burns calories well. No doubt about it. There is no reason that people who exericise daily should not be able to keep weight off.
Which makes me think it has more to do with the type of food eaten and hormones. What about stress and cortisol?
Cortisol will often make one hungrier, which in turn causes weight gain, but should not in itself lower metabolism. Long-term high cortisol levels will result in the redistribution of fat, though, in not such a good-looking way.
Does too much exercise and something like not sleeping enough cause weight gain?
Too much exercise (if there is such a thing... yes, I'm serious) should just make you leaner, though that may mean weighing a bit more. Not sleeping raises cortisol levels, which again raises your appetite. But it should not affect metabolism.
What about the type of food eaten and insulin/blood sugarlevels and their role in weight?
Again, I don't think the type of food matters much. It's the calories.
Blood sugar levels. Well, when they are low, you get hungry. When they are high, you are less hungry. Some foods cause high blood sugar immediately, followed by low blood sugar. These are typically sweets. And these make you gain weight because you get hungry when your blood sugar suddenly drops. If you can ignore that really low blood sugar, you can also lose weight just eating sweets, it's just a more painful process. But a calorie is a calorie!
Thanks so much for the questions, Kathleen! Sorry it took me so long to respond.