Reducing pack weight on a multi‑month hike has very clear benefits from both the scientific/medical side and from what long‑distance hikers report in practice. The short version: every extra kilogram costs you energy, increases joint and soft‑tissue loading, and raises your injury and fatigue risk day after day; cutting that weight meaningfully improves how far you can go, how you feel, and your chances of finishing.
Most thru‑hikers and experienced light‑packers aim for a “light but not stupid” zone: substantial reductions of nonessential weight and heavy legacy gear, while preserving warmth, shelter, and enough redundancy for the conditions