It’s an all-out war. A fierce, raging battle. On one side are those who are working to modify American eating habits to become healthier and more sensible in order to combat what have become epidemic levels of obesity and other dietary-related illnesses. On the other side are prepared food industries equally determined to increase their profits by enticing us to eat more and more of their products.

Sure, prepared food industries pay lip service to “healthy eating.” The Double Down – a breadless “sandwich” of two chicken breasts, two slices of bacon and two pieces of cheese – comes with either fried or grilled chicken (although all the commercials show only the fried version). McDonald’s offers salads, as does Taco Bell (in a fried tortilla bowl). The Golden Corral has a salad bar, and sugar-free Jello and chocolate pudding, which I seriously doubt is what’s bringing in most of their customers.

Much of the campaign to improve American eating habits focuses on what people eat. That’s fine. But just as important – perhaps even more important – is how often people are eating things that should be saved for occasional indulgences and how much (a.k.a. the portion size) they’re eating – not only junk and/or fast foods, but also otherwise healthy but calorie-dense items. Surveys show that Americans trying to maintain their weight ignore portion size – and that’s a mistake.

“If people could cut down on their portion sizes, this would be the single greatest way to combat the creeping obesity epidemic,” says Madelyn Fernstrom, founding director of the University of Pittsburgh Medical Center Weight Management Center.

The size of American food portions has been on the rise for four decades, roughly paralleling the rise of obesity and other diet-related illnesses. Those cute little bottles of Coke sometimes available during the holiday season that are sold as novelties? Those used to be standard size, in fact, the only size available.

Just how much everyday portion sizes have increased is brought home to me whenever I use the custard cups I inherited from my grandmother. Buff-colored ceramic with a glaze that’s cracked with age, they’re a treasure for me in part because they’re retro-cool, but mostly because they bring back memories of suppers from my childhood. We often had desserts for weeknight dinners. Most often it was fruit, fresh in season; in colder weather it might be a baked apple or berries, cherries or peaches frozen or canned by my mother and grandmother. Sometimes, though, we’d have baked custard, chocolate pudding or tapioca, served in those ceramic cups. They hold a half-cup. I didn’t think it was an unusually small serving – it was what we always had. These days, though, what’s in those cups seems almost miniscule.

Portion size has been increasing for some time – a really long time, according to researchers Brian and Craig Wansink. Brian is director of the Cornell University Food and Brand Lab and author of Mindless Eating: Why We Eat More Than We Think. His brother, Craig, is a biblical scholar at Virginia Wesleyan College. Jesus may have been the creator of “super-sizing” when he turned a few fish and loaves of bread into sustenance enough for multitudes. But the Wansinks, whose findings were published in the online International Journal of Obesity, say that portion sizes have been “marching heavenward” for 1,000 years. Using computers, the Wasinks analyzed 52 paintings of Christ’s Last Supper from the year 1000 to the year 2000. They used the size of the plates and the food servings on them as compared