Last week you read that research performed at the Penn State College of Medicine in Hershey and presented in June at the annual meeting of the Associated Professional Sleep Societies revealed that the amount of fat consumed at lunch, not the amount of carbohydrates, correlated to increased daytime sleepiness.

This work is newsworthy for two reasons. First, it contradicts a long-held notion that carbohydrates, especially simple ones eaten in isolation, make you sleepy. Second, it follows a trend of research that could radically change your views on dietary and body fat.

After research in the 1940s found a connection between eating a high-fat diet and having raised cholesterol levels that led to heart disease, a belief emerged, making fat the black sheep of the macronutrient family. By the 1960s, that belief became firmly established.

The belief: You eat carbs for energy, protein to replace and build muscle tissue, and fat, well, because it's naturally found meats and when added to foods it makes them taste much better. Just don't eat too much of it because it contains more than twice the calories of carbs and protein, and an excess leads to heart disease.

By the 1980s, the consumption of dietary fat was purported to be the primary reason for unwanted body fat, and the fat-free craze began, lasting well into the 1990s.

Unfortunately, eating fat-free foods only exacerbated the burgeoning obesity epidemic. Food manufacturers replaced dietary fat with all sorts of added sugars, primarily high-fructose corn syrup (HFCS), which tended to keep calorie counts essentially the same, and with "fat-free" boldly printed on labels many consumed such foods so liberally they actually ingested more total calories.

Since HFCS and most of the other added sugars get stored as fat nearly as easily as dietary fat, the attempt to eliminate one problem simply led to the creation of another.

So the pendulum swung back hard the other way. The Atkins diet reemerged, and only now we're back to collectively thinking that not all carbs are all bad.

So what are some of the new notions about fat?

Perhaps the most provocative is being postulated by a man who is still doing research at the age of 98. Fred Kummerow, professor emeritus of comparative biosciences at the University of Illinois believes that dietary cholesterol the reason some people still unnecessarily limit how many eggs they eat in a week is actually good for heart health in most cases.

Unfortunately fast food restaurants reuse frying oil, food producers use trans fat, and some people smoke. All three oxidize cholesterol, and it's not cholesterol per se, according to Kummerow, but only oxidized cholesterol that increases the buildup of calcium on the arterial walls.

It's this buildup that characterizes atherosclerosis, interrupts blood flow, and creates an environment in which heart attacks occur.

Kummerow's theory is held in such high regard that the American Journal of Cardiovascular Disease published it earlier this year. While it's based on his 60 years of research, a finding published in 2001 really gives the claim substance.

In this study, Kummerow and his coworkers found more oxidized cholesterol in the blood and tissue of subjects about to undergo heart bypass surgery than those subjects who were not scheduled for that surgery.

Another long-held notion about to change is the belief that body fat is inert. While it's still true that muscle requires calories to sustain itself and body fat does not, scientists now recognize that your body fat functions as a massive endocrine gland, and that the type just beneath the skin, subcutaneous fat actually produces hormones that regulate the metabolism and battle certain cancers.

The thought that any type of body fat could be good is radical, but subcutaneous fat has also been determined to help fight infection and heal wounds. Unfortunately, it's the type that diminishes with age.

And since the body fat percentage of most people increases as they age, this means the bad stuff is always on the rise. Visceral fat, the same type you see in an expensive cut of meat, works in between your muscles and organ, and is one example of the bad stuff.

It does the opposite of subcutaneous fat. Instead of fighting certain cancers, it produces proteins that have been linked to the creation of it, as well as overall inflammation.

Belly fat is also bad for your health. It leads to accelerated aging.

Proof of this was produced in 2008 by researchers in Israel who removed the abdominal fat on lab rats and found they lived longer on average than a control group. These researchers followed up the 2008 study by removing the abdominal fat of rats genetically created to develop colorectal cancers and found that many of the rats operated on never did.