A lot of the weight carried is essential stuff. Weapons, for example. But the Army saved two pounds in the 1960s when they switched from the M-14 rifle to the M-16. A lot of weight was saved in ammo carried as well, because a hundred M-16 bullets weighed two pounds less than a hundred M-14 ones. Troops usually carry 200-300 rounds of rife ammo with them. Plastic canteens replaced metal ones and lighter sleeping bags showed up, as well as lighter clothing. Lighter food (pouches of MREs instead of cans of C Rations). But heavier stuff was added, like the 17 pound "Interceptor" bullet proof vest and the heavier Kevlar helmet. Special Forces troops often go into action without the helmet and Interceptor vest and keep the load under 40 pounds. But that's only in those situations where the Special Forces calculate that speed and achieving surprise are worth more than the protection the vests provide. Most troops do not have that option.
American infantry are still carrying too much weight. It's a problem going back thousands of years, and few armies have been able to solve it. The U.S. Army had a team of researchers in Afghanistan to collect information on the situation and the numbers were not good. They found that the lightest load carried, the "fighting load" for situations where the troops were sneaking up on the enemy and might be involved in hand-to-hand combat, was 63 pounds. The "approach march load," for when infantry were moving up to a position where they would shed some weight to achieve their "fighting load", was 101 pounds. The heaviest load, 132 pounds, was the emergency approach march load, where troops had to move through terrain too difficult for vehicles. As in the past, the troops often ignored the rules and regulations and dumped gear so they could move, or keep moving. The researchers found that in Afghanistan, even though the infantry were in excellent physical shape, troops would sweat nearly 20 ounces of fluid an hour while marching at high altitudes in bright sunlight in moderate temperatures. That meant more weight, in water, had to be found to keep these guys going.
The solution may be one that the Romans adopted 2,000 years ago. When marching to a combat zone, Roman soldiers carried over a hundred pounds. Eventually, it was decided to give every squad of eight soldiers a mule to carry some of the load, and keep the troops fresh enough so they could do some strenuous fighting it they met enemy troops unexpectedly while on the march. A quiet, robotic, all terrain mechanical "mule" is what is being investigated. Fuel cells are about to enter service, and that is being looked at as a power source.
In the meantime, new rules for resupplying troops in combat, and what gear they can leave where when in a combat zone, are being studied. One good angle to this study is that they are actually talking to the troops about all this. As in the past, the infantry can come up with some very practical solutions to the problems the brass inflict on them. All you have to do is ask.