let me get this straight

in order to gain one pound in one day i would have to consume an additional 3500 calories on top of my maintenance (1400) calories?

Yep. If it's a pound of fat. Your weight can increase by more than a pound in a day without consuming that much more due to water retention or undigested food. But water weight and undigested food weight is temporary, and you shouldn't really consider it weight gain. It's really the fat that you need to be worried about.

yep

3500 over maintenance = 1lb

3500 calories = 1 lb of PURE FAT! Nothing good. You can maintain your calories but eat junk and still gain weight, like Jakinkale said, water weight, undigested food weight, and food waiting to be "realeased" weight. 

On the other hand, you can also eat well and still gain weight too, but if you go 3500 calories over your maintence, you are putting 1 lbs of pure fat, and a lot more lbs of water, food, and other bad stuff.

so even if you strength train everyone is saying that those extra calories will be stored as pure fat? Not some muscle also? I'm not so sure

The frustrating thing for everyone is that weight does fluctuate.  It looks like we're doing everything right and we don't lose, and then after a night out on the town we lose 4 lbs.  Sometimes our bodies just are not ready to part with it.

Jessinca, (ps if ca is CAlifornia, you ROCK!) I'm pretty sure it depends on what kind of fats from those extra calories you took in to be able to make them into muscle. Good fat and fat from protein, can be turned into muscle, but bad fat from soda and candy and junk it going to be next to impossible to turn into anything but fat. It has something to do with how the bad fat sticks to your tummy and works with your system. (thank you Magic School Bus). :-) 

Roxie10

Yes, that's funny about Magic School Bus, haha..

While it's theoretically true that a pound = 3500 cals,  our bodies defy logic with dieting and exercise for many reasons.  I think if you aim for a deficit of no more than 500 cal's if you're trying to lose, and a surplus of about 500 cal's if you're gaining, you can tweak your intake based on results.

Don't forget "Maintenance" means lying on a divan being fed peeled grapes by an attendant... If you move around at all, you'll burn more cal's than that.  If you eat around your maintenance (1400) and do some exercise, you may be undereating by too much to allow full recovery and build strength and lean mass.

Leftover calories that aren't needed for movement, tissue repair, or growth, etc, are stored as fat, but if you do aerobic exercise, your body will use your extra calories for fuel.  If you strength train, some of your calories will be used as fuel and some will be used to build increased muscle and bone mass (note: while you're resting or sleeping).  The calories will continue to be burned well into the next day. 

Building lean mass requires you to eat a little over maintenance in order to provide your body with something to build muscles out of.  You can still do this while losing weight by alternating strength-training days (or weeks) with periods of more high-intensity cardio or circuit trainng, which will allow you to 'zig-zag' your way to a leaner, stronger body. Also, the more muscle mass you have, the more calories you can burn lying on that divan being fed peeled grapes, haha.. so you can increase the 'Maintenance' calories accordingly.

note -- Most strength trainers (including me) believe that it's important to consume a small snack of lean protein and a quick-digesting source of med-high-glycemic carbs directly after strength training to see the best results.  Within 30-45 minutes or so.