My Struggles in the War Against the Office Chair

Over the 18 months I have transformed myself from an athletic, slim, happy, and fun-loving student to a slobby, lazy, overweight student who lives a boring sedentary lifestyle. There are a few factors that led to this happening.  First off. 2 years ago I moved to a new city to study Urban Planning.  In doing so my social life, which was once quite busy, was hacked down to virtually non-existent.  Much of my physical activity was a result of my social life.  I would regularly workout with friends, ski, play hockey, go dancing etc.  This was no longer the case once I moved, as I had no outlet for meeting new friends and didn't bother doing these things alone.  A few months after moving to the new city I started a school program that involves having to spend hours everyday parked in an office chair in front of a computer.  Although I did make new friends through school, due to the difficulty of our program and our sheer volume of homework meant that most of out hangout time was and continues to be spent enduring long hours in the lab.  This continues to be the case and I have now realized that with the career path I'm headed towards, I need to develop a plan to regain my old body and level fitness and maintain that state even though my career involves sedentary work.  
Recently I realized I had a gradually put on 60 lbs in the past 18 months, which is just absurd. When doing hours of homework I tend to snack without noticing.  Recently I calculated it and I was packing in at least 3000 calories a day and being in a state a denial, I knew I was putting on weight (obviously my clothes stopped fitting), but I was to afraid to weigh myself. I have been begun making small changes to my diet and no longer keep junk food in the house.   I'm also forcing myself to get up and move a bit more by running flights of stairs in my building.   Over the past several months I have spent far too much time sitting in this damn office chair, and on that note I'm headed off for a jog.   
Here's hoping that small diet changed every week and a little exercise get me where I need to go.