200 calories a day equates to one pound loss every 16 days, but to reach that level of metabolic slowdown, you need to be thin, and you need to cut your caloric intake down by about 1000 calories a day.
I was also being quite generous in that 200 estimate. While many people do anecdotally report that their maintenance level seems to be lower when cutting, I suspect that it's largely due to changes in physical activity as individuals are more easily exhausted on caloric deficits.
So yeah - it's a marginal effect.