Originally Posted by San
And no, there's no such thing as negative calories.
I have always been very curious about the claim certain foods have negative calories...meaning, it takes more calories to chew and digest the food than it contains.
Celery is probably the most oft-cited food of this sort.
So, the claim that negative calorie foods don't exist caused me to look it up. According to the Mayo clinic, several foods are said to have negative calories (once digested), but celery stands out because it contains so few calories to begin with (a typical stalk being 8 calories), and because it is so fibrous, the body has to work extra hard to digest it. ...Quickly exhuming more calories than the food contains.
I tend to be pretty skeptical, even of information from seemingly respectable sources. However, there are other respected sources who agree that some foods may, indeed, end up with a negative caloric impact, once digested.
Celery, partly because of this negative caloric claim, but also because it has a GI rank of 0, is one of my go-to snacks. I keep a food diary and weight graph. In combining the two at one point, I saw that, mere coincidence or not, the days I ate 7 or more celery sticks were the days I lost the most weight (regardless of other foods consumed). So, now I try to eat celery every day. I figure, it can't hurt. It's not like I'm eating 3 celery plants a day, at the expense of other nutritious food. It's really just a handful of medium-sized celery sticks. I've even become a bit of a celery connoisseur. Too dark green and you can bet the celery will be bitter. Too pale or too yellow, and it will be sour. Light green tastes the sweetest to me.
The info. from the Mayo clinic was quick to point out that no one has tried to quantify the exact caloric expenditure to digest a single stalk of celery. So, it is more presumption that more than 8 calories are used to chew and digest it. Their expert suggests about 10% of the daily calories we burn go to digestion.