"What does BMR, RMR, and Maintenance mean?"

Ok, there's a couple of terms running around that people get confused about.

First, there's the number of calories your body burns just by being alive. This is what the bodygem measures, and is not really a useful number except to estimate your actual daily burn. I call this RMR, because that's rarely confused with maintenance calories because "resting" is part of the name.

Second, there's the number of calories you actually burn in a day. You figure this by watching weight change over time. I sometimes call this BMR because others often think of it this way, but technically it's called "maintenance calories".

I apologize in advance for any confusion.

"How do I figure out my BMR/RMR/Maintenance?"

Track calories and weight loss. For every lb/week you lose, add 500 cals/day to your average calories. If you're gaining weight, subtract 500 for each lb/week gained. That's your maintenance calories for your current activity level.

RMR (resting metabolic rate) can be measured with a device called a BodyGem (or BodyMed for the pro version), available at many hospitals and health centers.

"In other words it's the minimum number of calories needed to maintain a healthy metabolism. This is why people should not be eating below their BMR."

While I generally suggest this also, I don't think it's strictly true. If you eat below RMR, you could just burn off fat stores to make up the difference. Whether this is healthy or not depends on a lot of other factors.