Well try 400-500 mg if it is magnesium oxide..the most common type. If that doesn't work after a few days try more the next day. Try to get as much calcium as magnesium to balance out. After 400 or 500 mg..if that doesn't do the trick increase real slowly so you don't get discomfort..you know what I mean... ;-)
PS Stop by my journal and let me know how you make out.

Try Milk of Magnesia - it's a sure thing. Take it at night, or on a day you don't have to go anywhere, because it will seriously clean you out. Like, SERIOUSLY.

Also make sure you're eating enough fat. I know you have additional complications with IBS, but I hear a lot of ppl complain of this on Atkins, etc, and eating enough fat really helps. Your body will take a week or two to normalize - your colon can get 'lazy' from a lot of fibre (because it rushes food through) and cutting back can be a bit of a shock until your colon gets the hint that it has to actually do the work now!

You may want to try taking some coconut oil in the mornings - some ppl mix it in things, I take it right from the spoon. Keeps things moving, and your skin will look AMAZING.

You're not too big now, and heading for what may be seriously thin. Your call. But fiber carbs don't count, so I'm a bit concerned that you could be cutting carbs too low.

Magnesium isn't exactly one of the chemical laxatives that can be so dangerous, but it's surely not fiber either, and with IBS, you don't need to be "I-ing" your B any more than it already is. Could be you're new to Atkins in addition to being new to the boards; can't tell. If so, LC eating will likely help the IBS. Take the fiber.

I use psyllium (Metamucil) flax meal and I eat 1/2 grapefruit twice a day so I have no problem. A small serving of plain sour yogurt can help.

Anyway, I just started taking 1oz Citrate of Magnesium before lunch as a magnesium supplement that's 1700mg. The whole bottle if taken for laxative effect; like before a bowel exam, is 10 ounces. That should give you an idea. I read MgO2 is not well absorbed and is found in the cheap vitamins.
BTW: Fiber is not really simple carbohydrate, its not digestable in the small bowel. That's why you see the terms Net or Impact carbs.

Well it worked, took about 7 hours though

Seriously, at 110 pounds at your height of 64 inches, if you are having IBS problems, it might be from not eating enough veggies. As for the constipation, if you are eating enough green veggies, it will help (I have had IBS for many many years, and that works best for me

I eat my 3 cups of spinach a day and have 2 Bowel Buddy cookies, they have 22 grams fiber and 9 grams non fiber carbs for both. I also take metamucil in capsule form 3 times a day, take an aditional fiber suplement in capsel form and 2 differnt herbal tonics for my bowel as well as drinking a very, very lot of water. Even with that I still have trouble on Atkins, and I used to eat alot more fruit and vegies back then. It used to take all that just to make me "normal" before I went on Atkins. Iv been on it about 3 weeks so far and lost 7 lbs if anyone is wondering.

This is not healthy at all. I'd really suggest seeing a doctor and discussing nutrition and healthy living. You're going to end up in the hospital or worse if you continue this way of eating.

EXCUSE ME!!!!!! But who made you an expert! And what exactly may I ask is so horrable about my way of eating!!!!! Its served me well this long. And I eat way better and way more on Atkins then when I was dieting before!

Neryceb - we are all concerned about you - that is all....what you are doing is not healthy for your body. Even you must know that, or you wouldn't be getting so upset. You are underweight, adn the reason Atkins is not working right now, is because your body has nothing left to lose! It is fighting back, and if this keeps up, your body will break down and you will get very sick. This is not to condemn you in any way at all...just to show some concern for you.

I have to agree with this. You are getting into dangerous territory with your health. Your body is going into survival mode because you are burning more fat than you need to sustain life. Just as I saw health issues arise with my weight being over what it should and saying enough was enough you should also look at being underweight and drawing a line somewhere.

Can I ask how old you are?

Fiber carbs are "free." You can eat as much fiber as you want and you don't have to count it because fiber doesn't raise blood sugar.

I'll be the third to agree. She's doing serious damage to her health, and she'll be lucky to NOT wind up in the hospital. She needs to GAIN weight, not lose and get used to the idea of looking HEALTHY instead of looking SKINNY.

She's 64". That makes her 5'3" and probably still growing. Going by the Met Life charts she is already underweight at 110, even for a tiny bone structure, and ciould weigh up to 147 for large bones. Her BMI is 19.5, which is already underweight. 100 pounds would be 17.7, even MORE underweight.

Gain some weight girl, and for God's sake, EAT!

Sorry, gotta step in here as a short gal - I'm 5'2" and am at a healthy weight and have a healthy BMI according to all those fabulous charts. I also have too much bodyfat, and it's quite obvious. My goal weight is 115, but I've been there before and did not look lean. I have a very small frame - maybe she does too. That said, I hope you, Neryceb, keep coming back bc no-one meant anything bad by their comments. Ppl here are extremely supportive and protective of one another - I love that about this place!

I don't think she meant she only eats 3 cups of spinach a day - did she? Did you? Anyway, I hope you're finding some relief. I have several friends with Crohn's and know that bran and other grain-based fibres can make things much worse in IBD and IBS situations.

Newbirth - Maybe our charts are different in Canada, but according to the Met Life chart my 5'4" sister is seriously underweight at 110lbs. She isn't. She has fab biceps and curvy hips, and a little buddha belly!