It’s a well-established fact: Americans eat more.

Several large studies have documented the increased calorie intake of Americans. This study, for instance, calculated a 440-calorie increased intake per day from 1977 to 2006 in 28,400 children and 36,800 adults. Increased calorie intake came from eating more frequently, more snacking, but not increased energy density of foods.

(The “p” rankings refer to percentile ranks, e.g., 10th percentile, 25th percentile, etc. of calorie intake. Data from the USDA Nationwide Food Consumption Survey and the National Health and Nutrition Examination Survey, or NHANES.)

You can see that calorie intake increased across all groups, across all eating habits, along the three time periods from 1977-78 to 2003-06.

But why? Many argue that it’s the increased accessibility of foods, e.g., vending machines, fast food restaurants on every corner, portable snack foods. Others argue that it’s largely a problem of soft drinks sweetened with high-fructose corn syrup that fail to induce satiety, since fructose is metabolized differently than glucose, not provoking an immediate insulin response. Still others argue that Americans are just plain gluttonous and lazy, the habits of Homer Simpson personified, choosing to eat more and exercise less just because they want to. Doh!

I think there’s merit to all of these arguments, though to a variable degree in different age groups, different individuals.

It’s odd, however, that the increase in calorie intake got its beginning in the late 1970s and early 1980s, precisely when the genetically newly-reconfigured wheat was introduced, complete with its new gliadin protein, differing from its predecessors by several amino acids. Recall that gliadin has been shown to exert opiate-like effects, able to bind to opiate receptors in the brain, blocked by opiate-blocking drugs like naloxone and naltrexone.

We also know that, when people with celiac disease remove all wheat/gluten from the diet, calorie intake goes down 400 calories per day. We know that normal volunteers administered an opiate-blocking drug, such as naloxone or naltrexone, experience a reduction in calories of around . . .  400 calories per day. We also know that people with eating disorders, such as binge eating disorder, reduce calorie intake, yup, 400 calories per day when injected with an opiate-blocking drug. We also know that a drug company files its FDA application in 2011 for naltrexone, a drug already on the market for heroin addiction, for a weight loss indication; in their clinical trials, overweight people taking naltrexone reduced calorie intake by . . . 400 calories per day, losing 22 pounds in the first 6 months.

Anecdotally, we also know that, if all wheat, and thereby gliadin, is removed from the diet, appetite and desire for food is much reduced. Calorie intake goes down, weight drops, visceral fat stores shrink. Read the stories on this blog and its Facebook page and you can see that this is not the exception; it is the rule (with few exceptions).

The gliadin protein of wheat is an appetite-stimulant: It increases desire for more wheat products, it increases desire for other foods, a constant cycle of hunger that drives increased consumption. It is responsible for stomach rumblings at 9 am after a 7 am breakfast. It’s responsible for the pattern of nocturnal grazing that many people experience, a constant need to snack after dinner. It’s responsible for midnight snacking, eating in the middle of the night when you surely do not need it. And most health-conscious adults are not drinking bottles and bottles of soft drinks, nor eating the crap foods from vending machines, or playing 4 hours of XBox every day. They are exercising, cutting their fat, and . . . eating more “healthy whole grains.”

What we don’t have is a specific gliadin versus placebo feeding study that, in a diet minus all wheat, is compared in calorie content. That is something I believe I should do.