Net or Gross Calories

People do all kinds of things. However, you shouldn't net less than 1200 and even that is extremely low for most people.

Right, for MOST people. There are some people who eat 1200 calories and that's a good amount for their body due to their size/metabolic rate.

That being said, when MFP gives you the amount of 1200 as your goal calories, that means if you ate 1200, then exercised, it operates as if you will then eat those calories back so that you don't go until 1200 at the end of the day. But if it's a day when you're not exercising, then it operates as if that's what you'll eat during the course of a whole day.

Thanks for the replies. MFP gives me 1200 as a goal but to be honest taking into account my body type etc I think that is too low. BMR for me is over 1800. At the moment I'm aiming for 1500 with a 1200 net so aiming to gain 500 cals at least from exercise.
It's a mine field!

Are you sure 1800 isn't your TDEE? You should never ever eat below our BMR. That is what it takes for your your body to function if you never left your bed for the day.

My mistake BMR is 1528 and TDEE is 2168

Eating below your BMR makes it difficult for your body to maintain lean muscle mass. At 1200 you will be losing a fair amount of muscle.

2168 less 20% = 1734. Eat this and don't worry about (net or gross) / eating exercise calories back. TDEE includes exercise up front....you're good to go.