"That fitness kook is crying wolf again."

If that's what you're thinking after reading the headline, you're wrong. Well, I may be a kook, but just like smoking a single cigarette, a single bad meal certainly affects you.In fact, the sentiment contained in the headline is why I got interested in nutrition as a teenager. To say I loved food, especially unhealthy food, back then would be right on target.The convenience store close to my favorite basketball court often ran a three-for-$1 special on Tastykake pies. There were many times that after playing all night my buddy and I would eat three pies each, drink a quart of iced tea, and reach a state we used to jokingly call "sugar shock."The French Apple and Tasty Klair pies, as I recall, were the best varieties. Berks County stores didn't carry Zimmerman's Iced Tea, so we were forced to make do with Turkey Hill.After junior high school games, our tradition was to walk to Pappy's Pizza and split a large pie topped with extra cheese and pepperoni and add packet upon packet of sugar to the free refills of iced tea. (At least the restaurant was more than a mile from the school.)Once when our team upset one of the junior high teams from Reading (that had kids who could dunk when not a single one of us could touch the rim), we broke that tradition by downing a bucket of KFC chicken and a dozen doughnuts.While we often joked the next day about food "hangovers" after pig outs like these, I believe we both suspected that there was an element of truth behind that.And then a few days into my junior year, I contracted a severe case of mononucleosis. Complications arose, and I was forced to eat what my doctor called a "very bland" diet.Steamed vegetables. Apple sauce. Tapioca pudding. Lots of soup broth.While I craved junk for a while, I had to admit that I felt more alert, more alive. Granted, I was still recovering from a serious illness, but now after a Sunday lunch, I wanted to do something other than take a nap on the sofa.After fully recovering from mono, my belief that single meals affected you became clear. I'd crave bad stuff, eat a ton of it, and then get that all-too-familiar food hangover. For a few days afterwards, I'd eat mostly beans, corn, grapes, apples, and big salads and feel so much better.When I left for college in August of 1979, I decided to experiment and follow a lacto-ovo vegetarian diet at least for a few months. I haven't stopped eating that way or experimenting yet.Why stop doing something that makes you feel really good and full of energy?Since my college days there have not only been dozens of studies to prove the long-term benefits of healthy eating, but also a handful of studies that show the damage done by a single unhealthy meal. One such study was led by Dr. Todd Anderson, the director of the Libin Cardiovascular Institute of Alberta and head of the cardiac science department at the University of Calgary.Anderson and his colleagues recruited healthy, non-smoking college students and then had them eat two typical breakfast sandwiches that totaled 900 calories and 50 grams of fat. Two hours later, he tested their VTI, velocity time integral, by temporarily interrupting the blood flow in their arms and then seeing how much the blood flow increases.On another date, the researchers took the subjects' VTI before they had any breakfast. They found that the bad breakfast a single bad breakfast that millions of people probably eat on their way to work decreased blood flow by 15 to 20 percent. Reduced blood makes it easier for fat to build up on the walls of arteries.So does eating meals that contain 450 cals of fat.The result of Anderson's experiment supports a University of Buffalo study published in 2004.Doctors fed nine healthy, normal-weight adults a rather unhealthy breakfast: a McDonald's Egg McMuffin, a Sausage McMuffin, and two servings of McDonald's hash-brown potatoes. The meal totaled 910 calories, 81 grams of carbs, 51 grams of fat, and 32 grams of protein.Blood samples were taken one, two, and three hours after the meal and compared to the samples taken from a test group that had nothing more than a glass of water for breakfast.The bad-breakfast group experienced an increase in what doctors call inflammatory factors, the sorts of things that can harden the arteries of healthy people, clog the arteries of the not-so-healthy, and possibly kill those with preexisting heart conditions.And the culprit was a single bad meal.Both Anderson's study and the University of Buffalo study show that a high-fat breakfast or any single high-fat meal, really increases the immediate risk of heart disease.The long-term risk of continually eating high-fat foods is so well established that other possible outcomes are no longer even offered.