When I was in the infantry (USMC) we carried alot of weight. Ammo, batteries, MG ammo, mortar rounds, grenades, food, water, personal items (socks etc.), sleeping gear, flak jacket etc. The weight was heavy, in fact Marines had to help each other to stand up.
That said, you do not go into combat with that weight. The packs had quick release catches. Hit them and the weight is gone. Leaving you with just your war gear. About 30 pounds.
Most men can not do this. Women can not. Sorry, body builder types make horrible infantrymen. They starve and their bodies start shutting down after a couple of days. Women's bodies are not designed to carry that much weight.
If you can not carry the weight, you can not get to the battlefield. If you can't get to the battlefield you are useless as an infantry man.
This is just for the rifleman. Mortar men, Machine gunners, add alot more weight.
Officers carry just as much weight. As a Company Commander, I carried extra batteries, ammo and mortar rounds. Like the private. Officers only fall out if they stroke out. (drop dead).