Caloric restriction and aging as viewed from Biosphere 2.
Level 4 - case-series / case-control
Uncontrolled case series / natural experiment in a small cohort (n=8)
What was done
Eight individuals sealed inside the Biosphere 2 closed ecological facility consumed a low-calorie, nutrient-dense diet for two years. Physiological markers—including body weight, blood cholesterol, blood pressure, fasting blood glucose, and white blood cell counts (along with ongoing monitoring of cortisol, insulin, and glycosylated hemoglobin)—were tracked to assess whether human responses resembled those seen in rodent caloric restriction models.
What was found
Over the two-year period, all eight participants demonstrated substantial weight loss alongside a marked fall in blood cholesterol, blood pressure, fasting blood sugar, and white blood cell counts. The abstract reports these directions of effect but provides no specific numerical values.
Why it matters
This report provides early evidence from a unique closed-environment natural experiment indicating that prolonged caloric restriction in humans induces metabolic shifts parallel to those observed in rodent longevity studies.
Limits
The sample size was extremely small (n=8) with no unconfined control group. No exact quantitative values or variance metrics are provided in the abstract, and hard clinical outcomes or lifespan effects were not measured.
Cited by
- supports Biosphere 2 was the site of the first human study on calorie restriction.