On Inca Trail to Machu Picchu the government renaoutilgs say that porters should not carry more than 25kg. But in practice, most of them carry at least 35kg (though almost never more than 45kg).The frustrating thing is, that if you want to do Inca Trail, you need to do it with an organized group and they will carry lots of useless stuff for you, e.g. a 4-person tent for each 2 people, tables, chairs, plates, cutlery and so on and so forth.In our group there were 13 tourists, 2 guides, 1 cook (who was also a porter), 16 regular porters, plus 4 extra porters that carried personal belongings of lazy/out-of-shape tourists. So we calculated that for the two of us (me and my husband) there were 3 porters (each carrying at least 25kg) on the trail, even though we carried all our personal stuff (clothes, sleeping bags and pads, water, and so on). If we would carry the ESSENTIAL things that the porters carried for us (like food, cooking equipment and a tent), it would only add 6-7kg of weight to our backpacks (instead of 3 25) The only good thing about this system is that it creates jobs. Also, porters on Inca Trail are reasonably well paid around $20-40/day (depending on the company). Though I still think they should be paid at least triple of that.