Overfeeding

I've been looking into overfeeding, as I ultimately want to see how this interacts with resistance training.  One of the first things I found is that with any type of overfeeding, regardless of exercise, some of the excess goes to lean tissue and some goes to fat.  This is intriguing to me, because you might figure that all the extra calories would go to fat.

Second, I've found that your starting point makes a difference as far as the effects of overfeeding.  This study looks at the differences in overfeeding in lean versus obese subjects.  In short, wtih obese subjects the extra calories were more likely to go to fat.

This same study also looked at the effects of excess carbohydrate versus excess fat.  The results showed that excess fat was more likely to be turned into bodyfat than excess carbohydrates.  But I think this relationship might be altered when exercise, specifically reistance training, is added to the equation.  Also, even though the excess carbohydrates led to less fat, it almost doubled fasting insulin levels. 

The connection with insulin also seems to be mediated by time.  This study shows that insulin action is mostly unaffected in short-term overfeeding.  So it may be that continual overfeeding that leads to higher insulin levels, and shorter cycles do not.

As far as how excess calories are split between lean tissue and fat tissue, the ratio seems to about 50/50 in healthy individuals given no real exercise component.  This is a good study(pdf) that tracks weight and other measures when subjects underwent overfeeding.

So the question becomes, can you get the ratio to 100 to zero, or all lean tissue gain with no fat gain?  I'm working on it...