I'm a previously 23 stone person. It took me almost 20 years of very gradual weight gain with a yoyo of about 5 stone every few years, to get to that size.
Initially I was always a chubbier teen, size 14 ish, but short, so not a healthy size 14. When I left home at 19, earning a relatively huge IT salary, life revolved around sitting down all day, drinking all evening and weekend and takeaway food. I then had a pregnancy and abusive relationship, left and comfort ate myself to about a size 24/26.
For the past 10 years or so, I've gone up and down between a size 22-30, been pregnant twice more and lost weight during pregnancy but put more on after due to pnd (was still very much a comfort eater), but for the past 5 years, things have been very different.
I went from about 19-23 stone without gaining more than 1-2 clothes sizes, so yes it really crept up on me. I tried lots of diets and exercise regimes, but nothing seemed to work...id lose 8lb in 4 months rather than in a week as I used to in years gone by. My eating habits changed as I no longer snacked and stopped drinking alcohol, but my portions were HUGE and I had a very sweet tooth.
I watch supersize/superskinny, sometimes with (superfit, Mr 6 Pack!) DH and we're incredulous at what the bigger people put away, as I've not eaten like that ever, even when I comfort ate...I like nice food :o. I was told once years ago that it takes a lot of calories/fat etc to get to my size but not as much to maintain it and this certainly rings true. None of my children or DH are an ounce overweight and we always eat the same....like I said, my portions were epic tho...
However, I had a gastric bypass last autumn and am now around 14stone and a size 16/18 :) and normally fitter and healthier than ever, doing exercise 5 times a week and as my problem was portion size, its been easy for me as this literally stops me being able to eat as much. I wish I'd done it years ago as now I can see the damage being so overweight was doing to me and my life - I was diagnosed with type 2 diabetes 12 months ago and that's completely gone for example.
In my research for the bypass which took me two years, I found lots of evidence that with BMI over 50, generally the body will not be able to lose the excess weight thru diet and exercise alone, obv with some exceptions, and this is some of the basis for the NICE guidelines for NHS weight loss surgery.
Not sure if this makes it any clearer for anyone, its just my story :) Off to read the whole thread now!