Nepal Trekking Routes provides you an experienced porter to carry your things during the trip. In some treks like Annapurna Circuit Trek, Upper Dolpo Trek, Everest Base Camp Trek, etc., you can hire a donkey to transport your things uphill and downhill.
A porter carries up to 25 kg of weight while a donkey can carry more than that. If you want, you can carry your backpack with the emergency stuffs and kits on your own.