You have this backwards. Insulin DOES help regulate fat storage (among other things). Leptin controls appetite and can act as an indication of overall adipose levels. It is conjectured that treating things like diabetes with both insulin and leptin together is better than insulin alone.
http://en.wikipedia.org/wiki/Leptin and http://en.wikipedia.org/wiki/Insulin
And I'll jump in on this calories vs everything else. If, as I've said many times before in other posts, all you care about is weight, only track calories (you'll most likely end up skinny-fat...but at a certain weight. Horray! You are now unhealthy at a lower weight. Congratulations!) If you care about losing fat, track macros and reduce carb intake to lose fat (along with weight lifting, HIIT and some carb-refeeds to manage hormone levels).
This is a rather complex topic, though I'm going to try and frame it a different way. What is the most effective way to put on lean, pure muscle mass? Weight lifting? A caloric surplus? High protein? Yeah, sure, all of that. Do you know what is even more effective? Steroids, specifically some combination of test, deca (or dbol), maybe some sustanon. What is the most effective way to lose body fat, particularly get to a ridiciously low level of body fat (think, getting on stage in a thong)? Caloric deficit? Low-carb? HIIT? hours of cardio? How about steroids again. Clen+Tren+Test. Sure, in both cases, caloric excess or deficit will help, but the stacks ALONE will work.
Why does that matter? Everyone always overlooks the hormones.
Why would it be any different if we don't talk about steroids? Hormones play a very important role in putting on muscle (think, stimulate the muscles by weight lifting, give them aminos (protein) to rebuild and spike insulin to make sure the muscles get the protein). And losing fat is no different (keeping fat high is vital to keeping testosterone high, protein to spare the muscles and lowerish carb to make the body look for an energy source (ie. fat) that you aren't providing. Throw in some weight training and HIIT to further deplete your glycogen stores. Viola, fat loss, muscle spared. Carb refeed once a week to reset your hormones (don't go into starvation mode) and you have a wash-rince-repeat cycle).
So, yes, calories matter, but only once you understand the broader picture. If you only talked calories, frankly, you can't be taken seriously.
I do have a saying, if your only go is "not be a fatass", then sure, there are many, many suboptimal ways to approach this problem. However, if you care about more than just not being a fatass, there is more to think about. Not much more, just a little bit. Overall, though, it is REALLY easy to get this right if you just can articulate your actual real goal.
heh "most likely end up skinny-fat"
I have visceral fat, though I have never been outside my target BMI range. The only time in my adult life that I did not have visceral fat was when I was on a low FAT diet (doctor prescribed) and exercising every day. I do not have pre-diabetes. Other than the visceral fat I show no other signs of metabolic syndrome.
But I don't go around telling people they should be eating more carbs. I don't tell people that eating carbs will make you skinny-fat.