I think I have a unique take on what others have already said, “All in Moderation”.
I've always been somewhat active, i.e. lifting weights and riding a bicycle as my primary form of transportation since the mid-80's; at one point I was cycling 50-miles (80 km) round trip, to-and-back from work. However, despite this I was still (as many do) gaining weight as I aged. The simple answer to this is usually that you just have a slow metabolism. I mindlessly accepted this, along with the “big-boned” excuse, emphasis on excuse.
Fast forward to 2006 when I hiked the Appalachian Trail. On the AT you have to ration your food, simply because there are no towns at every turn; I was spending on average a week on the trail before resupplying. In the beginning I was feeling miserable, because I wasn't eating near the same amount of calories I was conditioned to, not to mention I was hiking all day, up and down mountains with a pack on my back.
However, I experienced a dramatic change, so quick the change I couldn't believe it. I woke up one morning in town, went to breakfast and I ate and ate and ate...and I was never able to fill myself up to the point of having that bloated feeling; the food seemed to just evaporate on the way down. Not only did I not feel bloated, but when I started back on the AT after eating, the trail went straight up a huge hill; I went up it so quickly and nothing was slowing me down. This was about a month into my hike and my body had its first major change/acclimation to high volumes of exercise with reduced caloric input; my body only got more efficient after that.
Lesson learned: The body is super, super efficient. We humans eat way too much in modern life. The fact is that when we experience huger pains, it's not a signal that you need to eat, rather it's a signal that your body is spoiled. Also your body is super efficient at using body fat as fuel; however, if you try and exercise without eating you will feel weak and possibly lightheaded (like I was feeling in the beginning), but that's only because your body is spoiled, it wants more easily metabolized food, like what you stuff in your mouth. It's a total myth that you need X-amount of calories per day (chose your favorite recommendation), even if you're on an exercise regimen.
This was one of my most important life lessons. I can't imagine how much I'd weigh now if I never learned this lesson, much less the other health effects that come with over eating, which all Westerners suffer from and many others around the world and it's a growing global problem.
What does this have to do with carcinogenic celery?
I wouldn't worry about it; as others have said, All in Moderation. I'd worry about the ill effects of over-eating, far more dangerous, IMHO.
