Can someone explain to me the science of weight gain and weight loss? I know it sounds like a silly question, but why does it take longer to lose the weight than to gain it? It took me all of 8 weeks to gain 11 solid pounds and I find that it takes me twice (if not more) that amount of time to lose those 11 pounds. What gives?

Well, to be frank, it takes WAY less time to EAT calories than to burn them.

You eat 1 doughnut in approximately 5 minutes (1 minute if you're me), that's about 260 calories. You would have to walk fairly quickly (3.5mph) for an hour to burn that off. If you eat more than one, it would take 2 hours.

Well, to be frank, it takes WAY less time to EAT calories than to burn them.

You eat 1 doughnut in approximately 5 minutes (1 minute if you're me), that's about 260 calories. You would have to walk fairly quickly (3.5mph) for an hour to burn that off. If you eat more than one, it would take an additional hour per doughnut. I would eat 3 at a time, so in theory, I would have to spend 3 hours walking on a treadmill just to burn them off.

And I don't know why it posted twice when I edited...

Using myself as an example: I started 2009 aiming for 1500 calories a day, and reduced to 1400 in mid 2010. Based on my rate of loss, I expect to maintain at around 1750 calories a day.

This past week, I ate in the neighborhood of 2600 calories on Tuesday, 3000 each on Wednesday and Thursday. That's approximately 3350 calories above my estimated maintenance level, for a gain of about a pound, which agrees with what my scale is telling me.

Now, I noticeably overate, but I did not binge, and I wasn't full to the point of bursting--it was just normalish holiday eating. The illustration I'm trying to make is that it's not at all hard (for me, anyway), to go 1000-1500 calories *over* maintenance on a given day, but it's nearly impossible, or at least unhealthy, to eat 1000-1500 calories *under* maintenance in a day.

That's one possible answer to your question--it potentially can take very little time to gain weight, and a long time to lose that same weight, because it's easier to create a surplus than a deficit.

For me, the moral of the story is that, even when I know I'm overeating, I try to monitor the calories for two reasons: (1) makes it less likely I'll go completely overboard and (2) gives me an idea of how many calories to try to "pay back".

oboegal: thanks for the accuracy. Seems so simple laid out that way!

Thanks, fatmad. There are other ways of thinking about the question, and I'm not claiming that mine is "best", but I'm a math geek, and approaching weight loss as if it were a math problem has worked really well for me.

Thanks for everyone's input! This forum is such a great resource. I'm glad I found it!