Studies with animals have shown that caloric restriction may prolong life by protecting the brain from some effects of aging. The animals' diet was about half the usual calories they would consume. For people, 1250 to 1500 calories per day would be restrictive (compared to the 2000 calories or more that many of us in North America consume). Would it be worth it for a life span of 110 years? Describe the problems with such a diet