If you don't see any controls in your Accounts settings, then you can run each individual app and press the phone's Menu button to access that app's settings.
There has been a lot of speculation here that push Gmail is better for your battery than having your email program "poll" the Gmail server periodically.
There's an excellent, free app called Gsam Battery Monitor. It will give you a breakdown of what components of your phone used your battery since you pulled it off the charger (or you can put in a new starting point manually). If you run that, you'll see what apps are really using your juice. It will say something like App Usage...56%, and if you touch App Usage it will show you a breakdown by app. If you see an app near the top of the list that you haven't been using that day, you'll know it's been syncing.
But I don't know if the opposite is also true. I.e., is is possible for an app to use the phone radio for syncing but not show up high in the App Usage list as having used a lot of battery? Maybe others can address that point.