The SF Chronicle takes closer look at MRE development, a common food topic these days. The MRE weight needs to be under 1.5 pounds. It has to supply 1,250 calories and be edible for up to three years, stored at 80 degrees. It must be waterproof, vermin-proof and able to survive a 100-foot drop without a parachute. Because there are more women eating the MREs, folic acid and iron are now part of the added nutrients. Morale-boosting snacks (often used as poker currency) include M&Ms;, Lorna Doone cookies, Skittles and Jolly Ranchers.