Calorie Restriction (CR) is being promoted as a way of extending human life span based on experiments that show that CR increases longevity of monkeys, dogs, mice, and even worms. Americans, who are now the world’s fattest people, are aware that being overweight leads to cardiovascular disease and diabetes, but they seldom take steps to control their weight. Instead, doctors help Americans live longer by treating the symptoms of their indulgent life style with statins like Lipitor to lower cholesterol, oral glucophage tablets to help control high blood sugar levels, and thiazide diuretics to reduce high blood pressure.
Some people hear the message that CR extends lifespan by eliminating the diseases associated with obesity, and embrace the concept with great intensity. They go on severe diets, lose weight, and feel great until one day they discover that their bone density tests show bone loss and increased risk of fractures. How could this have happened?
Many nutrients are required to maintain bone mass. Bones require more than calcium. The glue that holds the bone minerals together is collagen, a protein. In order to preserve healthy bones while losing weight, it is necessary to practice Optimum Nutrition. You cannot simply stay on the Standard American Diet while cutting calories. The Standard American Diet, which is the basis for the USDA Reference Values, consists of 15% protein, 30% fat, and 55% carbohydrates. This provides only 75 grams of protein per day for a 2000-Calorie diet. If you reduce your intake by 300 Calories to try to lose approximately 2 pounds per month, the remaining 1700 Calories of American Standard diet will only provide 63 grams of protein per day which will put your bones at risk.
Lower calorie diets require proportionally higher percentages of protein such as those of the Zone diet which has 30% protein, 30% fat, and 40% carbohydrates. A 1700-Calorie diet with this proportion of nutrients will provide 127 grams of protein which will keep muscles and bones healthy while you lose weight. Of course, make sure that you also have adequate levels of calcium, phosphorus, magnesium, Vitamin D, and trace elements that help to maintain healthy bones — and don’t forget your weight-bearing exercises.