Couch potatoes and French-fried potatoes — these are the things we commonly blame for the obesity epidemic. But now, a new analysis indicates that it’s the potatoes more than the sofa making people fat. According to researchers in the Netherlands and the United Kingdom, people today are no less active than they were 20 years ago. In fact, the researchers found that subjects in the US and Europe burned an equivalent number of calories on a daily basis when compared to subjects in non-industrialized, developing countries and even when compared to wild animals.

“We found that people have not reduced their energy expenditure over the same period that obesity rates have increased enormously,” says Professor John Speakman from the University of Aberdeen. His co-author, Klaas Westerterp, from the University of Maastricht, illuminates the point: “Because we found no evidence for declines in energy expenditure over the last two decades, this work suggests that the obesity epidemic has been largely driven by increases in food intake.”

This doesn’t mean you should put your running shoes in storage. As I’ve said before, weight maintenance is a matter of calories “in” versus calories “out.” — with certain modifiers to the equation. But you do need to burn off what you consume. And so, the question becomes just how much more are you consuming than in the past?

Let’s look at the extent to which we’ve increased our food intake. By 2003, the average person consumed 523 more calories on a daily basis than did the average person in 1970. Unless those extra 523 calories get burned off, they’ll result in one pound gained every week, or 52 extra pounds a year. According to the study cited above, calorie burning has not increased over the years to burn off this potential extra weight. Thus, we find two-thirds of Americans falling into the overweight/obese camp.

What’s truly alarming is that those 523 extra calories primarily come from health-destroying sources. According to the USDA, “between 1970 and 2003, total per capita consumption of added fats and oils rose by 63 percent, grain consumption by 43 percent, …and sugar and sweetener consumption by 19 percent.” Also, intake of corn syrup, including the high-fructose stuff, increased 400 percent in that same 33-year window. And also in that same period, an ever-greater percentage of calories came from snack-foods. In 1977, the average American derived 11.3 percent of daily calories from snacks; by 1996 that figure had jumped 50 percent to 17.7 percent.

In addition to putting on the pounds, those unhealthy fats and sweeteners completely undermine overall health. And so, it’s not only the obesity we have to worry about — it’s the toxic, carcinogenic, heart clogging, diabetes promoting, health-busting effects of eating an average of 79 pounds of corn syrup and 86 pounds of processed fats every single year.

It also doesn’t help that portion sizes get larger all the time. Everything food-related has gotten bigger in the past 20 years — from dinner plate sizes, which were typically 10 inches back then and now average 12 inches (yes, that’s right, dinner plates have gotten bigger) — to bagels, which have tripled in calories over the years from an average 120 calories 20 years ago to an average 350 calories today. (Oh, and don’t forget the cream cheese and butter you smear on that bagel.) What does this mean? Studies show that we tend to eat what’s put before us — so bigger plates lead to bigger meals. A recent analysis showed that the average American now pours 20 percent more breakfast cereal and 30 percent more milk than back 20 years ago. And another, 2008 study, found that serving sizes have increased not only at restaurants and fast-food places, but also at home. In fact, burgers cooked at home have increased in size even more in the past 20 years than have restaurant burgers.

That’s disturbing news, given that a 2007 study published in the Journal of Public Health found that the average fast-food burger today is five times larger than when McDonald’s first started putting burgers to buns. Likewise, the average pizza slice has almost doubled in size in the past 20 years. The old eight-ounce bottle of Coke has given way to 12-ounce cans and 20-ounce bottles. And even your coffee isn’t what it once was. Back 20 years ago, the typical cup of coffee with milk and sugar measured eight ounces and 46 calories. Today’s Grande Café Mocha with 2% milk and a dollop of whipped topping rings up at 330 calories — a whopping 700% increase.

There’s no arguing with the fact that if you take in more calories, you have to burn off more calories. The proof is in the pudding, as they say — and in this case, the pudding is the stuff that jiggles around your waist, thighs, and butts when you walk. Hey, if you’re going to eat the jumbo platter, you’ve simply have to step up your exercise program to burn it off. How much? A lot! If we’re still talking about 523 extra calories a day, on average, then you’re talking about walking (if walking is your exercise) an extra 35-50 miles a week — just to hold even on your weight.

If you don’t want to run marathons, use smaller plates, eat fewer meals out, withdraw from fast-food snacks and all-things high fructose, and savor your meal. Because one of the saddest facts in this whole scenario is that while the majority of us continue to eat ever-increasing amounts of food, we seem to be enjoying our food less and less. A 2006 Gallup survey found that while 48% of the population enjoyed their food “a great deal” back in 1989, only 39% truly enjoyed mealtime just seven years later.

:hc