I have heard this "Starvation Mode" crap all over the internet and bb.com and it is so FALSE! (especially when applied to 250 pound guys who are lifting and doing cardio and eating 2000 calories a day)
Anyone who states something like, "eat more to lose weight" is just not thinking it through.
I have yet to see any study that suggests that the metabolism is slowed more than a FEW percentage points at extreme caloric depravation (say below 800 calories) but NEVER to the extent to create a Basil Metabolic Rate of below 800 cals. That is physically impossible. You body would burn more than that if it was in a coma! (unless you are a 4 foot tall 16 year old 85 pound girl...in a coma)
If you drop your calories below your BMR + exercise caloric expenditure you will lose weight period...can your BMR drop A FEW POINTS at below 800 calories - sure that has been proven. Are you going to go into go into starvation mode going from 2000 to 1500 calories to an extent that your BMR plummets by 600 points - Not possible!
To put it another way do you think that if you eat an extra 250 calorie snicker bar on top of your 2000 calorie diet your metabolism will be so revved by thinking it is out of danger that it will fire up the metabolic furnace and turn that noughat to ashes as it goes down your throat? - Not possible!
Bottom line - Your body's ability to reduce it's energy expenditure in response to caloric deprevation is a cool suvival response, but simply not powerful enough to make eat more to lose weight true. No Way.
( I know people will have a hernia about my generalizations, but in most cases that the metabolic slowdown concept is mentioned it is being applied and used incorrectly and it is starting to tick me of becasue the last thing these people need to hear is that they should eat more. They need to hear the hard truth which is - To Lose Weight Eat Less - )