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Ketosis: A Natural Part of Human Metabolism

2 min read
Ketosis

Ketosis is a natural metabolic state that humans have regularly entered throughout evolution, and even newborn babies transition into mild ketosis within days after birth — discover how this ancient mechanism supports energy needs from infancy to adulthood

Table of Contents

What is Ketosis?

Ketosis is a natural metabolic state where the body uses fat as its primary energy source instead of glucose (sugar). In this state, the liver produces molecules called ketone bodies, which provide fuel—especially to the brain—when glucose is in short supply.

Why Is Ketosis Natural?

Throughout most of human history, our ancestors lived as hunter-gatherers, without regular access to carbohydrates. Food supply was often inconsistent, and fasting periods were common, either due to travel, weather, or scarcity of food. During these times, the body naturally entered ketosis to survive and maintain energy.

For early humans: - There were extended periods with little or no food. - High-carbohydrate foods like grains and processed sugars were not part of the diet. - Energy had to come from fat stores between meals or hunts.

Ketosis was not a rare or dangerous condition—it was a normal part of daily life.

Babies Also Enter Ketosis After Birth

Interestingly, this natural state is also part of early human development. Although babies are not born in ketosis, they enter a mild state of ketosis within the first few days after birth. This happens as part of a healthy adaptation to life outside the womb.

After birth: - The constant flow of glucose from the mother stops. - The baby's blood sugar drops, triggering the body to begin producing ketones as an alternative energy source. - By day 2 or 3, healthy breastfed infants typically show ketone levels similar to those in adults during fasting.

This early-life ketosis is essential for providing energy to the baby’s growing brain during the first days of life.

Conclusion

Ketosis is not a "new diet trend"—it is a deeply rooted, natural part of our human biology. From hunter-gatherer ancestors who relied on it for survival, to newborn babies who depend on it in their first days, ketosis shows how amazing the human body is at adapting to different energy needs.

References

  1. Cahill GF. (2006). Fuel metabolism in starvation. New England Journal of Medicine. https://pubmed.ncbi.nlm.nih.gov/16848698/ (pdf)

  2. ... more under review...