CHARLESTON, S.C. — For many, a $10 or $20 cut in the monthly food budget would be absorbed with little notice.

But for millions of poor Americans who rely on food stamps, reductions that began this month present awful choices. One gallon of milk for the kids instead of two. No fresh broccoli for dinner or snacks to take to school. Weeks of grits and margarine for breakfast.

And for many, it will mean turning to a food pantry or a soup kitchen by the middle of the month.

“I don’t need a whole lot to eat,” said Leon Simmons, 63, who spends more than half of his monthly $832 Social Security income to rent a room in an East Charleston house. “But this month I know I’m not going to buy any meats.”

Mr. Simmons’s allotment from the federal Supplemental Nutrition Assistance Program, commonly called food stamps, has dropped $9. He has already spent the $33 he received for November.