Unless I'm totally misunderstanding what people here are saying, according to almost everything I've read here, you can't increase your muscle mass while trying to loss weight, since the first requires a calorie surplus and the other a calorie deficit. But I'm still confused about what goes on physiologically while losing weight through diet and cardio exercise. If I start doing a lot of cardio (running and rowing, in particular) and, through that exercise and a careful diet, maintain a calorie deficit, I should be able to lose fat while also becoming a better, faster runner. So, I'm wondering---if I'm maintaining, say, a 500 Cal/day deficit and losing about a pound of fat a week and am running, on average, 4 miles a day (which should be about 500 Cal/day) and am improving my athletic performance, what is really going on if I'm not building up muscle anywhere due to my calorie deficit? Am I really not gaining muscle mass anywhere, either in my legs or my myocardium? What, physiologically, is improving in my body if I'm not gaining leg or heart muscle? Is the improvement entirely due to improvements in blood vessels and the way the body delivers and uses energy?
Also, is it true for everyone that you can't gain muscle and lose fat simultaneously, or is it just true for people who are already high-muscle, low-fat? I know during the first spring that I ran track in high school, I had lost weight, but my calf muscles had certainly gotten bigger. And back then, I ate a lot of junk all the time.
Also, is it true for everyone that you can't gain muscle and lose fat simultaneously, or is it just true for people who are already high-muscle, low-fat? I know during the first spring that I ran track in high school, I had lost weight, but my calf muscles had certainly gotten bigger. And back then, I ate a lot of junk all the time.