This New England Journal of Medicine (NEJM) special report argues that the rising obesity epidemic will halt or reverse the two-century secular rise in US life expectancy (LE). Using a life-table counterfactual — estimating how much LE would rise if all obese Americans achieved the mortality risk of those with optimal body mass index (BMI = 24) — the authors calculate that obesity currently reduces US life expectancy by 0.33–0.93 years for white males and 0.30–1.08 years for black males, a burden exceeding all accidental deaths combined. Looking forward, they warn that as the obese cohorts now at young ages carry their elevated risk into middle and old age, the LE reduction could rise to 2–5 years — and that the children of today may live shorter lives than their parents. A secondary contribution is an analysis of the Social Security Administration's (SSA) historical LE forecasting record (Figs 2–3), documenting that SSA switched to optimistic extrapolation in the early 1980s precisely when LE gains at age 65 stalled.
"Forecasting life expectancy by extrapolating from the past is like forecasting the weather on the basis of its history. Looking out the window, we see a threatening storm — obesity — that will, if unchecked, have a negative effect on life expectancy."
"The U.S. population may be inadvertently saving Social Security by becoming more obese, but the price to be paid by obese people themselves and the economy is already high enough to justify considerably increased spending on public health interventions."
"Unless effective population-level interventions to reduce obesity are developed, the steady rise in life expectancy observed in the modern era may soon come to an end and the youth of today may, on average, live less healthy and possibly even shorter lives than their parents."
The paper's core quantitative contribution — a life-table decomposition showing obesity currently costs ~0.33–1.08 LE years — is methodologically sound and has held up. The secondary contribution — documenting the historical SSA forecasting record — is the empirically strongest part: the claim that SSA switched to optimistic extrapolation exactly when LE gains stalled at age 65 is documented from SSA's own published actuarial studies (1952, 1966, 1974, 1981, 1984, 1995, 2003).
The warning of an LE decline "within the first half of this century" was prescient: US LE peaked in 2014 and fell 2015–2017 — a decline realized within 10 years of publication. But the mechanism diverged. The actual decline came primarily from deaths of despair (drug overdose, suicide, alcohol), not obesity. This distinction is important: the paper correctly identified a structural fragility in US LE gains but misidentified the most proximate threat. Medical management of obesity-related conditions (statins, ACE inhibitors, better glycemic control) partially offset the obesity-mortality pathway in the subsequent decade.
The 2–5 year future LE reduction projection was likely too pessimistic even on obesity's own terms, because it assumed static medical management and full expression of current obesity prevalence through the age structure. But the direction was right. The paper's SSA-diabetes critique — that SSA projected improving diabetes death rates while actual rates were worsening — proved correct. Together with Soneji and King (2012), this paper established the case that SSA's intermediate-cost mortality projections were systematically optimistic, for distinct but complementary reasons.