From a report on sciencedaily.com:
QUOTE: A study investigating aging in mice has found that hormonal changes that occur when mice eat significantly less may help explain an already established phenomenon: a low calorie diet can extend the lifespan of rodents, a benefit that even regular exercise does not achieve.
“We know that being lean rather than obese is protective from many diseases, but key rodent studies tell us that being lean from eating less, as opposed to exercising more, has greater benefit for living longer. This study was designed to understand better why that is,�?said Derek M. Huffman, the study’s lead author...
They found:
* Mice allowed to eat as much as they wanted had higher insulin levels, regardless of whether they exercised. That is, how much the mice ate determined their insulin level, while exercise did not have much effect. High insulin levels are associated with a risk of diabetes.
* The animals that ate as much as they wanted and did not exercise had the highest levels of insulin-like growth factor (IGF-1), which plays a key role in regulating cell growth and cell death. The animals on caloric restriction had the lowest levels of IGF-1. Exercise also seemed to play an important role in regulating IGF-1 levels.
* There were some elevated levels of heat shock proteins, a measure of oxidative stress and possible tissue damage among the exercising mice. But total protein carbonyls, another stress measure, were not significantly different.
* Both exercise and caloric restriction moderated the level of 8-hydroxyguanosine (8-OHdG), a marker of DNA damage. Among the animals that ate all they wanted, those that did not exercise had the highest levels of 8-OHdG and those that exercised had much lower levels. The researchers concluded that DNA damage increases with age and is accelerated by obesity but could be slowed by caloric restriction and/or exercise. The researchers noted, however, that the results may differ if they had used older mice or subjected them to greater caloric restriction than the mild (9% fewer calories) or moderate (18%) restriction this study employed.
... the study suggests that caloric restriction creates beneficial changes in the body’s hormone levels which exercise does not. The researchers concluded that these metabolic changes play a role in extending life... UNQUOTE.
Souce: http://www.sciencedaily.com/releases/2008/05/080514064921.htm |
Free Forum Hosting
Important Announcement
First 