Chulin 99b - Gid Hanashe is Prohibited to Derive Benefit From

The gemara has a discussion in Pesachim about things that are prohibited to eat, whether they should also be prohibited to derive benefit from. Either way, one of the approaches to understand the nature of issurei achila - things that are prohibited to eat, is that it is essentially a prohibition to derive benefit, but the Torah only forbids the epitome of benefit from the item - eating. Meaning, that the nature of issur achila is that it is prohibited to derive the benefit that this item is meant to provide which is the benefit of eating. This would explain for example why we wouldn't consider an achila gassa (over eating), or eating of something which taste bad to be a violation of eating, since there is no pleasure or benefit associated with that eating. 

However, Tosafos makes a calculation in our sugya that undermines this premise. Tosafos proves from the gemara in Pesachim that according to the opinion who considers giddin (sinews) to have flavor, it is only prohibited to eat. But according to the opinion who doesn't consider it to have flavor, it is even prohibited to derive benefit from. Since we rule that Gid Ha'nashe doesn't give off flavor, we must rule that one cannot derive benefit from it - therefore it cannot be gifted to a goy, if the presence of the gid hanashe will raise the stature of the gift. Now, if one were to eat gid hanashe they would certainly be in violation of the prohibition to eat gid hanashe, even though there is no flavor so that they cannot be in violation of the issur to derive benefit. If it were true that the prohibition to eat is a form of deriving benefit, one couldn't be in violation of eating gid hanashe since there is no benefit and would only be in violation on selling or giving to a goy in which there is benefit. The fact that one is in violation even for the eating of gid hanashe which has no flavor, indicates that eating is in no way contingent on the pleasure or benefit one receives from the food, rather it is an act that the Torah forbids regardless of the benefit it provides.