You also, presumably, have ready access to limitless quantities of water, a mild exercise routine, and don't go prolonged periods on an extremely high sodium di

You also, presumably, have ready access to limitless quantities of water, a mild exercise routine, and don't go prolonged periods on an extremely high sodium diet. The root cause of constipation during an epic is almost always a prolonged period of mild to moderate dehydration. This can be caused by a lack of sufficient water, excessive exertion, excessive heat, excessive sodium intake, or most often all three in combination. People often become very dehydrated on long epics even in places with limitless water, eg rivers or snow-covered mountains. This is especially true in colder weather. I have rendered aid to dehydrated parties on snow-covered backpacking routes much more often than eg on the side of walls or in deserts. In the latter situations you know that water is precious and your body wants to hydrate. In the cold the mind doesn't want to hydrate and water doesn't seem so precious. Fiber always helps with constipation when your body is trying to preserve water because fiber pulls water into your digestive tract -- water which would otherwise be distributed in other ways by your body. If you are sufficiently hydrated then fiber often isn't necessary for healthy digestion. Do you ever go weeks at a time on 4000 calories of beef bouillon and horse jerky, a gallon or less of water, and 8 hours of mild to heavy exertion? When you do eat fresh meat, do you eat 9 pounds of steak each day? If not, then your definition of "meat-heavy diet" isn't the same as the L&C definition of "meat-heavy diet". If you ever find yourself in adverse conditions for prolonged periods -- in the alpine, high desert, or a big wall -- I highly recommend incorporating fiber into your rations. Particularly in the desert or on a wall, where staying hydrated is difficult because water is heavy.