What are the side effects of to much fibre in the diet?

Too much fiber: If you eat too much fiber without drinking enough water, your bowel can get constipated -- even obstructed if it's really bad. If you increase fiber more quickly than your system can manage, you can get abdominal cramps, gas, diarrhea, and intense urgency. Too much fiber could also mildly interfere with absorbing needed nutrients like calcium, magnesium, iron, and zinc.