Nigel at http://nigeepoo.blogspot.com/2012/02/what-i-believe-and-what-i-dont.html does a nice summary of what I basically believe also, so I will repost it.
Calories count (but don't bother counting them)! If we eat more than we use, we store the excess in fat mass and muscle mass. If we eat less than we use, we draw the deficit from fat mass and muscle mass. Insulin is involved in the storage of stuff, as is acylation stimulating protein (ASP).
Moving too little makes our skeletal muscle insulin resistant, as inactive muscles have virtually zero requirement for glucose and fatty acids, so down-regulate the uptake of them.
Eating too much and moving too little has sweet-F/A to do with gluttony and sloth.
Our weights are regulated by our brains, which are influenced by a large number of hormones & chemicals, including insulin. There is no "set point" weight.
In the winter, when it's cold and dark, we eat more, sleep more and move less so we gain body fat. Subcutaneous fat acts as heat insulation, so having more of it in the winter makes sense.
Our weights can be affected by water balance, which is controlled by our kidneys.
How much of a particular food we eat is influenced by reward. Some foods can be addictive (or moreish, as we say in the UK) due to excessive reward. Deliciousness and moreishness are not the same thing. Reward theory and set-point theory are not the same thing.
Rapidly-falling blood glucose level in the normal range can stimulate appetite. I have had personal experience of this on three occasions where my blood glucose level was being monitored. As eating a load of high-glycaemic carbohydrates can result in rapidly-falling blood glucose later, this is another good reason to not overeat refined carbohydrates.
And a summary of digestion http://rdfeinman.wordpress.com/2012/02/02/648/