moderato. adv. 1. (Music, other) at a moderate tempo. 2. (Music, other) (preceded by a tempo marking) a direction indicating that the tempo specified is to be used with restraint: allegro moderato.
While celery is a very low-calorie food, it likely doesn't provide you with negative calories. Mayo Clinic suggests that while it's theoretically possible for negative-calorie foods to exist, there are no reputable scientific studies that prove certain foods cause negative calorie effects.
The way you must look at it is how many calories does one stalk of celery contain, versus how many calories it takes to digest it. According to the nutrition data website, one 8 inch celery stalk contain about 6 calories.