I've been reading that most ppl regain some weight some weight after a couple years. I have also read that the maintenance..lifetime diet is to consist of 1000-1500 calories a day typically.

So my question is, if a person is eating 1500 calories a day, how could they possibly regain any weight?

Supposedly a 175 lb man needs at least 2000 calories a day just to maintain their weight.

Can anyone comment on this topic?

A lot of the numbers that we hear on these forums primarily apply to the ladies, as they are the dominant demographic in the WLS world. If one's metabolism keeps them stable at 1200 calories and they regularly consume 1500, regain will happen fairly quickly.

One of the problems that we have is that generalizing is difficult to do as there are so many variables involved, and the typical formulas to estimate metabolic rates don't work very well on us fatties and former fatties. Most, if not all, of us have some degree of metabolic damage from our obesity history (sometimes referred to as "the fat trap") where we don't burn calories as readily as normal people do, even after we lose the weight; it might be minor on the order of 10% or so, or major on the order of 50% or more difference from what we "should" burn. Degree of obesity, length of time at these higher weights and yo-yo dieting seem to be major contributing factors.

Most of us guys do have stronger metabolisms (strongly correlated to muscle or lean body mass) than the ladies overall, which is also why most programs put some emphasis on strength training over cardio exercise, along with our Protein intake, as a means of minimizing muscle loss during our weight loss phase. 2000+ calories would be a typical stable intake for an average 175 lb man, give or take some depending upon activity levels and metabolic damage (I'm maintaining in the 2000-2200 range) but there are some who wind up down in the 1200-1500 range.

Other issues that lead to regain involve our getting lazy over time - stop tracking our intake (we have it down, so why bother?), letting junk start slipping in again, drinking calories, cutting back on our exercise/activity levels as our new found energy becomes normal and we get busy with other things in iife (and don't compensate by cutting back our intake...)

I'm almost a year out. I eat between 1000-1200 calories a day. I usually fall closer to the 1000 but it depends on my exercise for the day. I was losing steadily until last month. I stalled for about a month. Got on the scale today and was down 4 lbs. I'm now 3 lbs from goal and have lost a total of 123 lbs. I'm very strict on my diet though and exercise a lot. Hope this helps.

I'm 69 years old, weigh 140-143 pounds, have been at this weight for 4 months, and average 1,700 calories a day. I walk most days, but am not a gym rat.

There's one datapoint for you. (And I know how much I eat, because I log ALL my food / drink into My Fitness Pal every day.)

Ignore anyone who tells you how much you should eat to maintain. They have no idea. You have to find out for yourself what YOUR maintenance level(s) are.

Good luck.