It’s good that 1200 is set as the bottom. But that is, as I pointed out, a bare minimum even for a small woman. It’s ridiculously low for someone who is at all active. At that level of intake, you will almost certainly see some loss of lean body mass. Even with a sedentary lifestyle, 1200 calories should be considered more like a hard bottom limit than a goal to shoot for.
Heck, to even get into that kind of range you have to be a bit obsessive about what you’re eating. Either that, or your actual calorie intake is significantly above what you think it is. It’s very hard for me to believe that eating that little is sustainable.
My wife is tiny, barely 5’1", under 110 lbs. and eats just slightly smaller portions than I do. She eats dessert more often, though. I estimate that she’s taking in around 2000 calories on average. She’s a Flamenco dancer, so while she’s pretty active for a couple of hours a few days a week she’s not doing really heavy exercise. At anything under about 1600–1800 calories she’d probably be hungry. At 1200 calories she’d be a raving bitch from constantly feeling like she was starving, and would eventually lose so much weight she’d be scrawny and unhealthy. Her lowest weight ever was 45 kg (about 100 lbs.) five or six years ago, when she was dancing around five days a week and was eating more than she does now. She used to eat more than me at that time, and I was at least 5 kg overweight! She was almost too skinny. Dieting would probably have put her in the hospital.
Even cutting Flamenco out entirely, I doubt she would be able to restrict calories to that level without some serious repercussions. She’d be cranky, have low energy, and would probably get sick a lot.
As I’ve related before, while I was never obese I did lose a significant amount of weight, through exercise primarily, so I’m also looking at this from a fitness point of view. If I cut calories much below what I already eat I’d start to see some impact on my performance pretty quickly, and I’m not what you would consider an elite athlete.
At 1800 calories, which is cited as the bottom limit for men, I would be running at about 400–700 calories below what I usually eat, as a male of average height and in currently good shape. I can almost guarantee that I’d have a downward trend in strength within a month, and would feel like crap in the bargain. While I might be able to manage it in the short term, in the long term I’d crash because it’s not sustainable at even my relatively moderate level of activity; I don’t do much long-distance work, so don’t really need a lot of calories above maintenance. I figure that my floor would probably be about 2200, which would quickly put me into single-digit body fat, while still having minimal impact on my activity. Even that would probably be too low to maintain for long.
