This research appears to be a couple years old, but I just ran into it. I know my own RMR is darned low, so this was a little bit of reassurance--there are people who have been tested down in what I expect is my range:

"In 14 years of work at the National Institute of Diabetes and Digestive and Kidney Diseases in Phoenix, obesity researcher Eric Ravussin (now at Eli Lilly in Indianapolis) recently uncovered some fascinating examples. He looked at the differences in how people burn energy and how those differences contribute to weight gain. The work made him appreciate how widely metabolic rates can vary.

"In a study of more than 500 volunteers, Ravussin and his colleague Pietro Tataranni analyzed resting metabolic rates--how much energy the body uses when it's just trying to maintain the status quo. The researchers gathered this information using a clear plastic ventilated hood that looks like something out of a viral-scare movie. It fits snugly around a subject's neck, continuously drawing in and siphoning off air. The wearer must lie awake for 40 minutes without moving. By measuring how much oxygen he consumes and how much carbon dioxide he breathes out, researchers can determine how much energy the subject spends on such basic functions as temperature control and involuntary muscle activity. Ravussin and Tataranni found that some of their volunteers burned as few as 1,067 calories a day, while others burned as many as 3,015."