An uncontollably sweet tooth was my downfall. Got worse over the years to the point where I wasn't actually eating proper food anymore and my diet consisted of chocolate, cereal, cakes etc. Very rarely did I eat a meal, holidays and when going out but apart from that just junk. I don't believe there is any underlying reason other than I ate what I enjoyed, I got fat, got depressed, ate more rubbish, got fatter and so we enter the viscious spiral!!
Gxx