I use a poplar site called my fitness pal for tracking my calories and exercise goals. My BMI is 41, my BMR is 1736 calories, and my TDEE is 2388.
my stats are female, 5' 3" at 232 lbs, 31 years old.
I input my info for height, weight, and age into my fitness pal and they recommended a calorie range of 1500 calories with lightly active as my activity level in order to lose 1-2 lbs a week. I burn about 500 calories or more when i walk which takes a little over an hour. I have recently added in 2-3 days of 30 minute weight lifting to maintain muscle tone as well.

I started walking 4 miles a day, 5 days a week 2-3 months ago, and eating cleaner (i got rid of soda, candy, chips, etc) and have lost nearly 20 lbs from my starting weight of 250. thus far i feel good at 1500 calories, not hungry, or exhausted.

however, i did hear that eating below your BMR is dangerous and can severely mess up your metabolism. I don't want to do that, but I don't want to up my calories and gain back all the weight i have lost.

does anyone have any ideas on whether this is going to severely screw up my metabolism? maybe i need more calories?

I think what you may have read in reference to eating below your BMR being bad is probably related to people looking to build muscle, not someone looking to lose weight.

1500 is fine. You have to eat a VERY low calorie diet for a VERY long time for it to cause starvation mode or to have a significant impact on your metabolism. Sounds like you're doing just fine.

You're losing at a reasonable pace. You feel good, you're not hungry, that's all excellent. Keep doing what you're doing!

If you were at risk of damaging your metabolism, you would feel rotten, exhausted, sleep more, living with near constant ravenous hunger with insane cravings for HEALTHY things, think wanting to pick up a rotisserie chicken and eat the thing whole, fantasizing about salads and hard boiled eggs, that sort of stuff.

In nearly 10 years of mentoring on a bodybuilding board I saw two categories of true metabolic damage. One: Hormonally related, this included post pregnancy and perimenopausal. Women are at an 8 times higher risk of thyroid disease because there is a very real link between estrogen and thyroid hormone. Hormonal surges can create issues and hormones are linked to diet. A sluggish thyroid can slow your metabolism by around 15%, enough to allow serious weight creep or make weight loss close to impossible. Also, my personal observation is that hypothyroid impacts your appetite. Your body is low on energy so it sends a signal the only way it can, stimulating appetite saying "SEND CALORIES!"

The second way I've seen metabolisms damaged is with SEVERE dieting in an already lean individual. Women who compete in bodybuilding competitions generally have something like 12% bodyfat (compare that with the average normal weight woman carrying around 25%). I've known a couple competitors who didn't want to give up that ripped look, despite repeated warnings to get off the restrictive diet and gain necessary fat. In one woman it created a horrible cascading hormone crash. But bear in mind, that woman was attempting to maintain close to a 10% bodyfat.

Finally, read this: http://www.nowloss.com/starvation-mode-myth.htm

Congratulations again on the success you've had with your journey and keep up the good work!

No. Like others have said, the best way to lose weight is to eat as little as you are comfortable with.

Once you decide to build yourself up again (to look good), that is when you need to eat enough and enough of the right foods.