The changes that actually cut pack weight, ranked by grams saved per pound spent

Asked a lot of people what made the biggest difference. The answers cluster hard and almost none of them are the things beginners buy first.

The three that matter
Pack, shelter and sleep system are most of your base weight, and cutting any one of them beats everything else combined. In order of what people named:

• The pack itself. Often the single heaviest item, and a large traditional pack with a heavy suspension is carrying weight you no longer have once the rest is light. This is also why it has to come last: buy the light pack after the load is small, not before.
• Shelter. The biggest single saving available, and the one requiring the most acceptance. A trekking pole shelter or a tarp is a fraction of a freestanding tent.
• Quilt instead of a sleeping bag. Same warmth, less material, and it removes the compressed insulation you were lying on anyway.

Free or nearly free

• Weigh everything you own and write it down. Universally named as the thing that changed behaviour, because the surprises are never where people expect. Costs the price of a kitchen scale.
• Leave the things you did not use last trip. Keep a list at the end of each trip of what never came out of the pack.
• Repackage. Food out of retail packaging, toiletries into small bottles, no stuff sacks you do not need.
• Fewer clothes. The most common excess by a distance. One worn set, one sleep set, one insulating layer.

Where people waste money: shaving grams off small expensive items while carrying four spare shirts. The scale tells you this immediately, which is why it is first.