Physiologic changes in humans subjected to severe, selective calorie restriction for two years in biosphere 2: health, aging, and toxicological perspectives.

Biosphere 2 is a closed ecological space of 7-million cubic feet near Tucson, AZ, containing 7 biomes: rain forest, Savannah, ocean, marsh, desert, agricultural station, and habitat for humans and domestic animals. Sealed inside, 4 men and 4 women maintained themselves and the various systems for 2 years. All organic material, all water, and nearly all air was recycled, and virtually all food was grown inside. On the low calorie but nutrient-dense diet available, the men sustained 18% and the women 10% weight loss, mostly within the first 6 to 9 months. The nature of the diet duplicated rodent diets that had been shown to enhance health, lower disease incidence, and retard aging. Using blood specimens frozen at different points during and after the 2 years, determinations were made of a number of biochemical parameters judged to be pertinent based on past studies of rodents and monkeys on similar diets. These included blood lipids, glucose, insulin, glycosylated hemoglobin, renin, and others. The results clearly suggest that humans react to such a nutritional regime similarly to other vertebrates. In addition to these studies, and because this was a tightly closed, isolated environment, the levels of insecticides or pollutants or their derivatives were determined in the sera of 2 crew members. It was found that levels of the lipophilic toxicant DDE and the "total PCB" load increased with the loss of body fat during the first 12-18 months inside Biosphere 2, then decreased.