I have been having issues with my bowel movements

Dr.  I am a 24 year old 5'11 male.  I never really noticed myself having frequent diarrhea at all during my life.  While I was younger, the only time I noticed having it was early mornings when I would wake up, without having much sleep the night before.  No other signs of this.

Last year, when I was 23, I was strength training and conditioning as I am no longer playing a college sport, I wanted to keep active in the gym.  I started taking protein, and two other over the counter GNC supplements.  NO STEROIDS.  But every time I would have these supplements, I would often have diarrhea.  I told my trainer about the diarrhea and he said it was normal.  At this time, I weighed about 205lbs, and was very much in shape.  

As I got more serious in my career over the past 8 months, I stopped going to the gym as it hasn't been fitting my schedule.  I gained 25lbs, and now weigh 230lbs.  Ever since I stopped working out, and using the supplements, I thought maybe the diarrhea on occasion would stop.  Now what I am realizing is certain foods that I eat are causing me to have diarrhea, sometimes immediately right after I eat.  For instance, Chinese Food, it goes right through me, if I go to the movies and have that buttered popcorn, it goes right through me and some other types of foods, not all though (For instance, I can eat Italian Food all day, and am fine).  When I go out and drink liquor or beer, the next day I have diarrhea normally.  When I wake up early in the morning, and rush to work without getting much sleep the night before, I also usually have diarrhea that morning at work.

I definitely do notice, that if I eat healthy, and eat foods that don't upset my stomach, I do have normal stools and no problems with this.  I have weeded out for the most part what does or doesn't affect my stomach. I have spoken to friends who are nutritionists, I've spoken to my uncle who is a doctor, and all of them for the most part are saying its because : 1) whatever some of the food that I eat is cooked in may be upsetting my stomach, 2) by gaining this weight, and not actively working out like I used to, my body isn't used to not being in "shape", now my body is reacting different to these foods, 3) lack of sleep and stress could possibly have an affect in this matter.

My nutritionist friend says its actually a good thing to go to the bathroom more frequently, rather then not so frequently.  My girlfriend clearly sees me in the bathroom so she thinks something is wrong with me. Meanwhile, she maybe goes to the bathroom once a day or once every other day, which I think is weird, because clearly I am going 2x or usually more a day.  I am just confused, I don't know if something is wrong with me, if I should steer away from those foods completely? Or is it okay to still eat the Chinese food?  Should I stop worrying about it?  Is this normal? What do you advise me to do?

I recently started going back to the gym in the mornings, should I continue to use those supplements?  Please advise me to what to do.

Dominic 4-7-09