Many folk have diarrhoea while low carbing.

Try psyllium husks. Psyllium is very useful stuff - it fixes both constipation and diarrhoea by softening while adding bulk.

You can take it as capsules, or, the cheaper option, just buy the raw husks and add 1 tablespoon to a glass of water. It tastes kinda like chaff but adding a bit of lemon juice helps.

Do make sure you are drinking plenty of water while taking psyllium.

Cheers.

Rosebud