The light-weight pack required for backpacking and traveling in the Alps is the kind that needs a lot less space than normal backpacks. All you need is a medium or small sized backpack that fits comfortably around your shoulders (40-45cm), and then take the essentials from the outdoors that you really need: clothes, toiletries and a change of shoes.
When traveling in a group, we would normally keep it light and everyone would bring their own necessities: clothes, toiletries, kitchenware, and maybe an extra piece of equipment, like a rain jacket.
We would also include an extra heavy pack for emergency evacuation. With the essentials packed in, and the heavier load, we would still need the light pack to carry our food and water.
Lightweight Traveler’s Options
There are several options when packing for light-traveling backpacking:
Small backpacks
The smallest backpack you can find is probably a ziplock bag. I would recommend finding one that has a width of 40cm (just a little larger than a normal small backpack) and size of 38-40cm, which should weigh just 5-8lbs. The straps should be rigid, and you should have a good lock for the zips. A small pack is a good way to carry all of the essential items, but keep in mind that it will take you longer to walk if you have an awkward load on your back. On trips where you want to walk around a lot or walk through beautiful alpine trails, you will certainly need to take a bigger pack.
Lightweight backpack for hiking
Another option for light-traveling backpacking is just a small bag, like a light-weight, camouflage backpack that fits in your waistband (aka hip belt). The lighter weight allows you to pack the essentials and then just take the pack in your hand and enjoy your time on the trail.
Large backpacks
It may be a little harder to find a large backpack to travel light in, but with larger packs it becomes easier. The large backpacks will probably be too heavy for a lightweight backpacker to use, but they will also likely be a little bulkier and can take up more space in your suitcase and campsite if you travel a lot.
Start with a small pack
Smaller packs will typically take longer to walk with. Keep in mind that if you have a heavy pack you will certainly be slower to move, and the little pack won’t be enough to cover your essential items. The only way to really find out if you can carry a small pack is to carry it around for a few hours, and if you get tired, stop. If you don’t have to stop, and still want to go further, you should take the pack with you and carry the heavy load. But if you do have a heavy load, take the pack with you but then leave it for the last leg of your trip.
Jamming something like a foldable camping chair into any backpack would take up the kind of space that can be saved with a walking stick seat instead, of which the foldable one you can sneak in as your carry-on, hand-luggage.
