...but about 6 years ago, I went from about 205 to less than 170 in about 8 months or so (so about 1.25 pounds per week). I did it mainly by avoiding carbs and sugars and I ate a "Paleo" diet for the most part, but I also did pay some attention to calories. I do feel like the limited carbs had as much/more impact than limiting calories, because it caused my body to start using fat for energy instead of storing it.

I have kept my weight fairly steady since, although I intentionally gained back about 10-15 pounds because I had gotten way too thin for my height, to the point that several people asked if I was ill. I felt great but I was scrawny. However, I was diagnosed with Celiac disease a couple of years ago, which on one hand has made avoiding some carbs very easy (and necessary), but it has also pushed me towards others at times. For a while, I ended up eating a lot of rice and corn-based foods, so I ended up gaining a little more weight back. Back in February I decided to cut way back on carbs again and I've lost about 10-15 pounds since. This time I'm not paying any attention to calories. In fact, I'm following the general Paleo rule of thumb that calories from fats and greens are good and you can consume as many as you want. An interesting side note is that I've noticed a significant decrease in inflammation while limiting carb intake. I was suffering from extremely painful plantar fasciitis, and it subsided significantly within days of cutting back on carbs (it has since flared up on the few occasions that I have eaten lots of carbs, so I feel there is enough evidence to assume a link).

I'm no dietician, but I do think you are wise to be cautious to not eat too few calories. You don't want to slow your metabolism. You just want to change the way your metabolism works.