Some people do experience some constipation for the first week or two on alli. It may be due to the change in diet, or that not enough water is being consumed. It's important to have at least 8 to 10 glasses of water each day.
Constipation, under any circumstances, may be a result of too little fat. Fat acts as a natural lubricant. It's also important to have the recommended amount of fat from the alli calculator for best weight loss results on the program.
I hope this helps. Please let me know if you need anything else.
Pat Baird, MA, RD, registered dietitian