I have no gall bladdder and I take Welchol for my bile diarrhea. You'll have to get a g.i. to prescribe it since it's an off-label use that most G.P.'s don't know about (it's a cholesterol medicine). It binds up the bile in the intestines and keeps you from have those long bouts of diarrhea. I take one a day right now, but I can take more as needed. I can eat pretty much anything I want, although I avoid really hot/spicy foods, apples and caffiene. It can be constipating, so you have to self-regulate based on what you eat.
I eat pretty much the same thing every morning for breakfast, and very similar things for lunch and also for supper, so my fat levels stay about the same, so I need about the same level of medicine each day. Switching your diet around a lot, I have found, makes the diarrhea more unpredicatble; you need to be pretty unvarying in your meals in order to keep from having attacks. Me, I eat a roll with some Nutella on it for breakfast, have a salad, a potato-based soup and usually some sort of dip or salsa and tortalla chips for lunch, then I have nachos or fajitas or stirfry or spaghetti or pizza for supper. Same things, all week long. Then I change up the next week. This makes making supper faster (because I can cook a week's worth all on one night) and my stomach is more consistent than it's ever been. Luckily for me, I've never cared for food diversity; when I get to craving something, I crave it every day for weeks at a time. You'll note that while I avoid fried foods, I don't avoid fat (Nutella, potato soups, candy for desserts). The fat is okay as long as it's the same amount of fat everyday. Vary from your norm either way--too little or too much--and you'll have issues. And while your family may complain about having spaghetti every night of the week, it's actually cheaper to just cook the one thing and eat on it for a whole week; it means you can buy in bulk and have less spoilage. And children are actually more likely to like having the same thing for days at a time; the repeativeness is comforting (they always know what they're having for supper) and they tend to want the same thing all the time anyways--like always wanting pizza or always wanting burgers.
I have given up on the weight thing . I am the same weight now that I was before I had the gall bladder removed (a size 14 American), so I'm not really fussed about it. I did go on a diet and lose a couple of dress sizes, but it came back on eventually. It always does. 95%-98% of all dieters regain all or even more of their weight within 1-3 years. I had worse self-esteem after dieting than before dieting and it really messed up my guts. See, too little fat in your diet causes constipation. If you are keeping a low fat diet, that's probably why you get constipated. Then change your fat level just a bit and you get the diarrhea. When I was dieting I had constipation every bit as bad as I had had diarrhea before. I missed work because of it and everything. I definitely do not recommend any person with IBS go on a diet; it will make things much worse than weight loss will ever make better. Eat to make your guts healthy; don't worry about the rest.
I understand your concern about diabetes. I hate to be a downer, but I was just reading in my fiance's diabetes magazine about a woman who kept her weight at 125 pounds, walked briskly for 30 minutes 4 times a day and kept a very low fat diet rich in fruits, vegetables and whole grains. And she was just diagnosed with diabetes, high blood pressure and high cholesterol. What else could she do? The doctor, whose advice column it was, admitted that 20% of all people who get Type II diabetes are not overweight at all. That she had had gestational diabetes marked her as someone who was genetically prone to get Type II diabetes (50% of all women with gestational diabetes develop Type II later) and really, there was nothing she could have done to prevent it. The blood pressure and cholesterol were genetic too. That she had been super healthy meant that these things had only been delayed in coming on until her late 50's, but she was fated to get them either way. So, trying to diet may keep the weight off--provided you diet every day for the rest of your life--but it probably won't help you not develop diabetes if your genes are programmed that way. It may, as in this lady's case, delay the development, but if that causes you to have life-long stomach problems, then it's probably not a good trade off. They have medicines to treat diabetes, but almost none for IBS; it's a combination of diet, various supplements, off-label prescriptions and reading star alignments to try and keep it under control. And diabetes hasn't kept my fiance in the house like my diarrhea has.
So my advice to people is always, always, treat your stomach first. If it's not healthy, you just can't function or have any quality of life.