Just in time for the holidays, researchers have published a study that shows that even a few weeks of overeating can wreak havoc on a person's cholesterol levels.
The study, to discover what happens to people in developing countries given the high-fat diet of developed nations, involved Tarahumara Indians in Mexico whose normal diet of corn, beans and other low-fat foods keeps heart disease at bay.
Martha P. McMurry and her colleagues at the Oregon Health Sciences University in Portland plied their 13 subjects with a diet high in fat, cholesterol, sugar and calories.
After five weeks of the rich diet, their cholesterol levels had shot up 33 percent. Their weight increased by 7 percent.
"We're not saying you should eat only corn and beans over the holidays," co-author and dietitian Sonja Connor said. "We are suggesting you avoid excessive fats and that you exercise regularly."
Too much sunshine can add about 9 inches of wrinkles to a middle-aged woman's face and nearly five years to her apparent age, a study suggests.
The results appeared in 22 white women ages 45 to 51 who had lived in Tucson, Ariz., for at least a decade.
The work was reported in November's Journal of the American Academy of Dermatology by researchers at Procter & Gamble Co., the University of Pennsylvania in Philadelphia and the Oregon Regional Primate Research Center in Beaverton.
Photos of the women without makeup were shown to another group of 24 women who were asked how old the participating women looked. Women with high sun exposure ranked an average of 58.2 years, compared to 53.7 years for the others. In fact, both groups of women averaged around 47.7 years old.
Men who over-exercise have lower hormone levels and may be doing their bodies and minds more harm than good, researchers who conducted a study on exercise said last week. .
Everyone has a critical activity threshold, a point at which exercise ceases to be beneficial and instead leads to physical and mental problems, according to Garry Wheeler, a physiologist with a University of Alberta research center.
For men, crossing that threshold can result in lower male hormone levels that can affect muscle development and bone density, he said.
Over a six-month period, Mr. Wheeler's research team compared hormone levels in men who ran over 60 miles a week with those who jogged 33 miles a week and a group that did not exercise.
"We found the higher the mileage the lower their testosterone level was," Mr. Wheeler said.
The implications of over-exercising are very serious since testosterone is necessary to muscle development and bone regrowth, he said.
The problem is compounded since people who over-exercise often take in fewer calories which curbs the body's ability to regenerate itself.
Mr. Wheeler's research shows high-mileage runners ate 1,800 calories a day compared to 2,000 calories for those who ran less.
Earlier studies have found below-normal levels of the female hormone estrogen in women who exercise heavily. The university team wanted to find out if the same condition occurred in men. However, there is no proof that over-exercise affects reproductive ability, he said.