I wrote recently about my body holding on to a weight set point like grim death. My suspicion has always been that weight gain or loss is not directly related to calorie intake. I think calorie intake is one factor, but not 100% of the picture. This article in the NY Times is relevant, and a little bit of a downer to read. Here are some excerpts, although the whole article is definitely worth reading.
"Every time the result was the same. The weight, so painstakingly lost, came right back...There were a very few who did not get fat again, but they made staying thin their life’s work, becoming Weight Watchers lecturers, for example, and, always counting calories and maintaining themselves in a permanent state of starvation.
The implications were clear. There is a reason that fat people cannot stay thin after they diet and that thin people cannot stay fat when they force themselves to gain weight. The body’s metabolism speeds up or slows down to keep weight within a narrow range. Gain weight and the metabolism can as much as double; lose weight and it can slow to half its original speed."
I don't think any weight loss venture is hopeless, but I agree that weight lost will come back unless one is hyper-vigilant. I notice that I personally have been thinnest when I've had a more active lifestyle, such as walking a couple of miles each day and working out in addition to that. Genetically, I think I'm destined to be thin, but an extra 20-25 lbs has crept on due to my desk job and suburban life. I'm looking to increase my daily activity past the 5 hrs a week I spend working out, and hopefully the cubicle physique will fall by the wayside.
In terms of diet, I definitely don't want to stay in "a permanent state of starvation." I'm moving my diet towards lots of vegetables, small amounts of whole grains and nuts, and minimal sugar or white grains. A bowl of vegetable soup is very filling and has few calories, and it's that type of food that I want to have as my mainstay.