I read this once in a “little known facts” e-mail (I know, not the best source of reliable information:rolleyes: ). Is there really such a thing as ‘negative calories’? In other words, is it true that digesting celery for example takes more calories than the body can get out of the celery? If so, is there any other ‘food’ that does this?
I think digesting sawdust would probably use more calories than it provides. And you would also get that full feeling and be less hungry at mealtime 
A perfect first post, Still Cooking, and welcome!
Raw potatoes will lose you more calories than you gain. You could eat raw potatoes till you’re stuffed day in and day out but you’d eventually starve to death (of course a raw potato only diet probably has a few other issues that would bother you along the way).
Cooked potatoes are another matter. Cooking breaks they very long carbohydrate molecules in potatoes for you so your body has less work to do upon digestion and will see a net gain for eating them.
This isn’t to say eating raw potatoes is harmful. Just don’t eat them to the exclusion of everything else.
Thanks, ** DarrenS **. I had done a search, but clearly I didn’t look hard enough.
I remember from a TV program about survival in the wilderness that you should avoid mushrooms, even if you know that they are edible, on the grounds that there is so little nutrition in them that you will spend more calories looking for them than you will gain from eating them.
I have never liked mushrooms anyway. 