Send this Article to a friend
By: Jerry Brainium
While the final results won't be available for another 20 years or so, the preliminary results show that the rhesus and squirrel monkeys that are eating an average of 30 percent fewer calories than other monkeys are aging slower. They handle glucose better and show decreased insulin levels and increased insulin sensitivity. Those markers for aging all are indicative of a decreased incidence of diabetes.
Diabetes is considered an aging-accelerated disease, since the inability to dispose of excess glucose that's characteristic of diabetes causes glucose to wind up in places it shouldn't be, such as interlaced with protein structures. That process, known as glycation, leads to the stiffened connective tissues commonly seen in older people. The good news is, there are some drugs that may break up such glucose-and-protein crosslinking, and nutrients such as alpha lipoic acid may help prevent it too.
The monkeys on the CR regimen are also showing less incidence of cancer than the other monkeys. That's significant because cancer incidence increases with age. It's thought to occur due to an impaired immune system or to the effects of free radicals on cellular structures. Both are considerably blunted by CR. Mice studies also show that CR may help block cancer by decreasing insulinlike growth factor 1 (IGF-1). While local IGF-1 synthesized in muscle helps to foster muscular repair after exercise, systemic IGF-1 promotes cellular growth, including that of tumors.
On a genetic level, a study published in the August 27, 1999, issue of Science found that CR blocked 84 percent of the activity of genes that trigger cellular aging. Other genes, such as those governing such beneficial processes as response to overheating, DNA repair and oxidative stress, doubled in activity after a CR eating plan.
Those were all animal-based studies, however. CR proponents point to two pieces of evidence to bolster their assertion that CR is the best way to forestall the aging process. One involves people living on the island of Okinawa, near Japan, who show a 40-fold increase in their odds of living to 100 over other people. Their diets average only 1,100 calories a day, but they appear to thrive.1
The other case involves an ecological experiment funded by Texas oil billionaire Ed Bass. Called Biosphere-2 (Biosphere-1 is Earth), it was a three-acre, seven-million-foot enclosed ecological domed space located just outside Tucson, Arizona. The biosphere was supposed to simulate how a colony living in outer space might survive and thrive, and it featured several types of habitats, including a rain forest, savanna, desert, ocean, marsh, agricultural station and living quarters. Four men and four women, including Roy Walford, allowed themselves to be sealed into Biosphere-2 from 1991 to 1993.
Several unforeseen events occurred, and the people living in the biosphere were forced to live on a CR diet, averaging about 1,800 calories daily. That resulted in an average weight loss of 18 percent in the men and 10 percent in the women. Their diet also led to reductions in resting glucose, insulin and cholesterol levels; however, when they emerged from the dome in 1993, most of them looked more haggard than youthful. The Bodybuilding Plan
The good news in terms of CR's implications for bodybuilding is that animal studies show that it helps preserve youthful-appearing muscles. In a study of rats reported in the June 1997 issue of the FASB journal, a diet that restricted calories to 35 to 50 percent of normal led to a prevention of age-related muscle fiber loss and decreased muscle mitochondrial damage due to oxidation effects. The rats in the study began the diet at the human equivalent of middle age.
A rat study published in the journal Biology of Sport in 1995 found that rats on a typical CR regimen of 30 percent reduced calories that exercised for 30 days showed decreased growth and decreased liver and muscle glycogen content. Even worse, they showed decreased activity of the enzymes used in fat oxidation. The rats did only endurance, or aerobic, exercise, which appeared to promote catabolic processes in muscle when combined with significantly reduced calories.
A recent study featured 13 men and 11 physically fit women who reduced their required daily caloric intake by 750 calories, 60 percent of which came from carbohydrates.2 They engaged in treadmill running during the two-week study, and 61 percent of weight loss during that time consisted of lean tissue mass along with increased nitrogen loss, which points to muscle protein breakdown. Despite being in a clearly catabolic state, subjects in the CR group showed no loss of muscle strength, and they had increased muscle endurance.
The picture changes, however, with weight-training exercise. Numerous studies have shown that animals can increase muscle size even on a starvation diet, provided some form of weight resistance is placed on muscles. A recent rat study showed that while overloaded muscle is protected by weight training during calorie restriction, fast-twitch muscle'the type most prone to growth'is most adversely affected by significant drops in calories, while slow-twitch, or endurance, muscle is comparatively spared under such conditions.3
A study of women who went on a reduced-calorie diet compared groups who lifted weights with those who only dieted.4 Not only didn't the women who lifted and dieted lose any muscle, but they actually gained muscle mass.
[ Prev 1 2 3 Next ]