The book suggests that diet is a crucial differentiator, contrasting key dietary components and "biomarkers" (such as body weight, temperature, blood insulin and glucose, cholesterol, etc.)

Estep is active in longevity and aging research and in criticizing anti-aging claims he suggests are unrealistic or poorly supported.

Longenity folded but the company published research showing that a calorie restricted diet feminizes gene expression (in mice) and that it regulates both sirtuin and TOR aging regulatory pathways.

[8] He has been highly critical of strategies for engineered negligible senescence (SENS), a plan to reverse and repair the damage of aging.

Some commentators have been critical of this requirement, saying that virtually any idea is worthy of some level of learned debate, though the terms of the prize were known in advance to all participants.

Estep and colleagues failed to win the $20,000 prize on offer, but Technology Review's editor, Jason Pontin, nevertheless awarded them $10,000 for their "careful scholarship".

Estep has been openly critical of SENS and of Aubrey de Grey for alleged misrepresentation of scientific evidence, and he suggests that the SENS plan does not address some of the most challenging aspects of aging including unrepaired DNA damage, noncancerous mutation and epimutation of the nuclear genome, and drift of cell and tissue-specific chromatin states.

[11] In March 2020 in response to the Covid-19 pandemic, Estep founded the non-profit, open-source Rapid Deployment Vaccine Collaborative (RaDVaC), serving as Chief Science Officer.