what is a calorie deficit

It means how many more calories you should be eating. It is the calories you are 'short'.

If you need, say, 1700 calories, on average, per day to maintain your bodyweight i.e. neither losing nor gaining weight, and you actually only eat 1200 calories per day, then your calorie deficit is the difference, 500 calories.

A calorie deficit of 500 per day, or 3500 per week would result in roughly a 1lb per week weight loss in most people.

Ok i get it thanks guys but still if im been told i need 1,200 without exercise to lose 2lb a week but then like today i exercise and it adds an extra 599 cals what exactly should i be eatting???it says 1,799 but surely if i want to lose weight i should eat that amount,i dont have a lot to lose i actaully lost over 12st but have put back on a stone in a year and just cant get it back off!!

yes because your 1200 is already a deficit, probably a fairly large one, so eat 1799

I use the numbers it gives me in the goals page for figuring out appropriate deficit. If I do NOT exercise, it says I burn about 1850 calories but, as an adult female, I NEED a minimum of 1200 calories just to keep my body running properly and prevent it from going into 'survival mode' and ... If I work out, I look at the total calories burned for the day and subtract at least 500 hundred, but no more than 1000 calories from the total calories burned that day and eat within that window. (More than a thousand calories defecit will cause 'survival/starvation mode' patterns).

So, working out at the pool I burned say 365 calories... My Goals Page tells me that my calories burned per day without exercise is 1850 calories (just 'being'). I add 365 to 1850 (2215) and subtract 500 to 1000 calories from that. So, if I eat anywhere in the range of 1215 to 1715 calories, I will still have an appropriate deficit and continue to lose weight without my body freaking out. (I tend to stay within the -800 calorie range if I can.)

Clear as mud?
I hope this is helpful anyway.
~Namaste

Hi your post was helpful I do still have a question. Im just starting myfitnesspal. But here is the question.

so with the calorie deficit. my calorie goal is 1600 my calorie deficit is 360 to lose 1.1lb a week..ok...today I ate 1760 calories, i exercised and burned 258 calories so it left me with a net of 1502 and 98 calories remaining to eat..I guess so does it mean I need to eat 98 calories to stay within my deficit of 360 to lose 1.1lb a week. second question If I eat less than my goal calorie isnt that good more weight loss a week like if i do not eat those 98 calories and let my net calorie stay 1502 isnt that better than getting the 1600 ? confused:huh:

remember all of these are a guide. everyone's physiology is different. The best thing you can do is eat as clean as possible. It's incredibly difficult (in my experience) to eat 2,500 kcal of truly clean food. I get to about 2,000 and want to barf from being too full.

1200 is a pretty safe threshold not to fall under, especially if you are working out. other than that, find out what works for you.