Each April, Live Below the Line.com has an international movement of people who eat on $1.50 per day to mirror what it's like for the majority of the population. After studying poverty in various countries, my students undertook their own Live Below the Line service learning project. They actually ate on less than $2 a day (I gave a little more wiggle room), kept diaries, collected receipts and reported back to the class about it. Many encouraged their families to join them too. The results of this project were phenomenal - students gained a true appreciation for their lives and a greater understanding of what people living in poverty go through, even just little things, like how one can become more angry when they haven't eaten. A powerful project!
Note: I made this a voluntary, extra credit project, as I of course cannot dictate what students eat/don't eat.