I have diarrhea after meals. why? no other symptoms?

Your symptoms are suggesting a dumping-like mechanism in which multiple organs may be involved, including stomach, small bowel, pancreas and liver/gallbladder. Best would be to get work up started early with your primary care physician as significant nutritional deficiencies and weight loss are likely to occur in time.

If you have lost weight without trying to lose it, it is imperative that you consult a GI specialist. If weight is stable, try taking Imodium in the morning. Make sure to drink enough water to stay hydrated. Have a healthy diet, http://www.choosemyplate.gov exercise 30 minutes/day, drink plenty of water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs