While you don't
have to eat back your calories expended by exercising, it also won't
hurt you.
If your body needs 1300 calories to lose weight and you are eating that amount, by burning 400 calories, your body is only getting 900 calories. While this might result in losing weight faster, is it healthy for your body?
There are some theories that your net calories should be 1300 calories. That would be Calorie Intake - Calories Burned = Net Calories.
You could eat 1700 calories minus 400 calories burned to equal 1300 net calories.
An estimate of what you need to maintain your current body weight would be to multiply your weight by 12.
185 x 12 = 2220 calories a day x 7 = 15,540 calories a week
To lose one pound a week, you need to reduce your total
weekly intake by 3500 or 500 calories a day. So technically, you could lose weight by eating 1720 calories a day. (2220 - 500 = 1720) Figure in your exercise calories burned of 400 and your net calories would be 1320 calories.
Currently your net total is about 900 calories. If this is a reoccurring event, your body could go into starvation mode because you are dropping your net calories below 1200. Here's a link with info on
starvation mode.