200 pounds overweight and CAN'T have any substantial loss.

Would you consider making your food diary public? Then we can see what you're eating and that would help us see what's going on.

I know that diet is a significant portion of weight loss.... but I think that exercise helps more for some people. You need to move. If you have a very sedentary life, then 1600-1800 calories may just be keeping you at maintenance. I'd try busting down to 1400 for a week to ten days and see what happens... or get some exercise in there. I started with just walking the block around work

Sometimes it takes a little time for ur effort to pay off. Dont expect massive weight loss over night. U will get there as long as u hand on heart are being honest with yourself and not ommiting things to make ur food diary look bad.

It's hard to know how many calories you're actually eating unless you log everything. Be honest with yourself no matter what you eat and your habits will change. I wish you much success in your journey.

Keep a journal - or use MFP everyday. Be religious about it. Really find out where all your calories go. I wouldn't be surprised if you were going over 1800 if you aren't keeping a strict log of every calorie. Everything you put in your mouth, log it.

Are you drinking sodas? If so, you need to cut that out right away and stick with water. It's not fun to drink your calories... even though I would love a Mountain Dew right now. I'd rather eat my calories.

You asked for long term... this is the beginning of the rest of your life. Make this lifestyle change now. Eat clean (google that if you don't know what that means), drink lots of water (at least 8 cups a day) and watch your calories. Keep up the exercise! Good luck!

Are you counting your calories accurately? I have struggled up and down with the same issues, but I've realized that beginning this is a process... I am still surprised sometimes by how many calories are in something, and I mess up a lot thinking things are "no big deal".

For example, on Monday I decided to trade my regular coffee for a french vanilla, only to discover that the FV was over 500 calories, which is 300 more than my regular coffee. So to make up for it, I had to eat a really small lunch, which left me hungry all day, and then I binged on dinner. I won't be making that mistake again!

Sometimes those little things we don't think matter, add up to a LOT. Careful with drinks and be sure to log everything you eat accurately.

Also, are you eating back excercise calories? There's a lot of different opinions out there but you have to see what works for YOU. I'm still figuring my body out, but I've been trying to maintain my regular calories and only eating back excercise ones if I'm hungry and I feel as though I need to. Or say, I'll eat back 1/3 of them.

Good luck!

It could be if your food is high in sugars, fat or other not so good things. Being just under calories isn't always what works. It has to be good food too I do wish you lots of luck on your weight loss journey. You can do it !!!!!!!

This isn't necessarily true. Where you have a substantial amount to lose, just staying under should be enough for a while. I'd venture to say that you're eating more than you think. For instance, a standard apple you buy at the grocery store is usually about 2 of any serving size on MFP based on weight. You can also consume a TON of calories in the form of creamer in your coffee, a few m&m's, a bite of a co-worker's salad, etc. Be mindful of these things as well.

If you're over 300 pounds, then 1600 calories a day may simply be too few and your body's metabolism is slowing because it senses a big loss. Talk to your doctor to set the most appropriate daily range for caloric intake.

I haven't been the best with getting food logged

This is probably why you haven't lost. In order to really tell what you need to fix to lose weight you must log everything you eat, every day. Because those unlogged calories add up and could very well be sabotaging your weight loss efforts more than you realize.

Also, if you made your food diary public, it would help get you more constructive feedback based on what you're eating (such as foods to swap out that would be healthier choices).

I logged everything I ate for at least a month and didn't lose a pound (may have even gained a little). I have stopped logging and lost 7 pounds in the last month or so. It all depends on what works for you.

Making her diary public probably won't help all that much if she hasn't been good about logging.

first thing - Open your diary so people can see what your eating and give you options, swaps and other alternatives.
Next, make sure your drinking lots and lots of water, and try to get as most non-processed food as possible into your diet. Plan ahead your meals, it works.

As someone that at 200lbs to lose, about the same place you are, I'm being told that I need to eat more when I am exercising. You gotta eat those exercise calories. 1600 and 1800 cals a day is fine for smaller girls, but if your holding onto a whole extra person, your burning that off in a day just by breathing. (search BMR calculators)

Might need to see if you can get in a session with a dietitian. I found out that having a personal trainer helped me greatly as well. If you can afford it, maybe you can do one session and have them check up on you like once a month or every few months to tweak things with you. It will also help with accountability and you'll get a ton of face to face thoughts on what to do better.

Its a slow process to get things right but I am finding out myself, that it works. Its a lifestyle change and you can't change everything at once, just go slowly, put things in one by one until you get to where you need to be at. You can do it.