Negative calories? Do they exist?

Are there such things as negative calories, my friend and i were having a debate about it, she believes there is no such thing and i really don't know what to think.

Do fruits/veg such as carrots, cabbage, spinach, strawberries, plums...etc.  have negative calories??

Negative calorie foods are foods that take more calories to eat than they contain.  For example, if you were to eat Item A - Item A contains 20 calories, but you exert 30 calories to eat it.

I think it's bollocks, because essentially your body burns all the calories you eat (unless you go over your BMR).  Thus, I wouldn't count them as negative.

Hi Sarah, I believe that even if they do have negative calories, they really don?t make much of a difference, (as in if you eat only the so called negative calorie foods, you will never put on weight. I dont think thats true) I don?t think that?s possible. I?m a vegetarian, and my diet is mainly made up of grains, fruits and veggies, and eggs. I think the term negative calorie came into existence for those veggies and fruits, that are pretty low in calorie in nature, and are easily burned therefore don?t get stored as fat in your body even though they are carbs. Just the fact that they are a different set of carbs other than grains such as rice(which tend to end up as fat in your body if not burned) .

Another way to look at it is a pound of sweets is equal to a pound of veggies in weight, but you are probably not going to put on weight because of the veggies, but because of the sweets.

Celery does.  But the significance of "negative calorie foods" is overrated. 

I hope I'm not way off topic but a friend here helped me tweak my diet.  I was eating all this healthy stuff not loosing.  She says what are you eating?   I said well I eat rice w/veg's and pasta w/ veg's
potatoes and apples on and on I told her the things I was eating.
She said there's your problem.  If you not loosing get rid of the pasta the rice and the potatoes and see what happens.  I started loosing!
Oh and I had to boot bread.  Actually, I'm eating bread like every
other day. I chose the healthy kind.  Right now I have spelt bread.

just thought I'd mention that calories can make a differance in what you eat. 

Lysistrata beat me to it.

The only things that have negative calories are below-body-temperature water, and celery. And even then the difference is very trivial, and the main benefits of these two things is that they don't really add to your caloric intake, and they can replace foods/drinks that do. I add the calories in celery to my logs anyway, about 6 per stalk, but you actually burn more than that eating and digesting it.