There is no such thing as the "starvation mode" as thought of by dieters. Your metabolism will drop slightly with extended calorie restriction in response to less body mass (as you lose weight) but won't drop to zero (or you would be dead).
The internet is full of people that supposedly gained weight on 500-1000 calorie diets yet no metabolic ward study (where someone else controls the food) has ever actually found one of these people.
There are several issues that make it seem like it exists. One is that food charts are frequently wrong and can be off as much as 20%. Also, it's impossible to get an 100% accurate calorie count on some things, like meat, because the actual fat content varies so much.
Also, there are short term effects that can mask your actual fat loss. Water is the worst as it can vary by several pounds a day. Women have it worst here because hormonal changes can cause them to gain a lot of water weight in a short time. You have to do it consistently for a longer period of time to get an accurate picture of what is going on. A few days won't show it and can be deceiving.
Here is an extreme example:
http://www.ncbi.
.nih.gov/pmc/articles/PMC2495396/
A 27 year old man fasted with nothing but water and a few supplements for 382 consecutive days. He went from 456 pounds to 180 pounds. Tests during his fast showed he didn't lose all of his muscle. He also maintained at 196 pounds five years later so he didn't wreck his metabolism and gain it all right back.