How bad for you is it to have negative net calories for the day?

[Bradford3]

Today I biked 50k and played around of golf while only eating 1900 calories to 4600 burned and accoring to MFP I am -450 Net calories for the day. 

Here is my week. Note I think something is off with Net Calroies Under weekly goal at the bottom. 

[JHMP]

Same question I guess. I thought that was part of my goal, i.e., burn more than I take in.

[RivalDealer]

How do you feel?

Mine is similar, I feel fine doing it and it's working so until it stops working I will keep on doing it.

[SuperStephSteph]

If you were doing that every day you might have a problem, but it looks like you're netting a negetive calorie intake only once in a while so you should be just fine. 

[Heybales]

Ditto to every blue moon not being a problem, but be willing to go over the next day when your body may still be trying to recover and be hungry.

And if you intend to do a decent workout the next day, or have energy, you'll likely discover it does the body good not to leave a huge deficit. You feeling hungry and your body being fully fed are not related - you can easily fool your hunger signals.

And huge misunderstanding on the goal of burning more than you eat.

It's not to burn off more in exercise than you eat - because then you are leaving out rest of the day, which is for most burning more than the exercise is.

Your eating goal ALREADY has a deficit for weight loss built in to it - if you indeed selected a weight loss goal.

You reach your goal eating level - you don't attempt to go under.

Bigger deficit is not better, not long term - rarely short term either.