The sugar was the best available option to quickly replenish strength, especially when trekking in mountainous areas in the middle of nowhere, Yang said.

"Once you have set off you never know when you will reach the next populated area," the 58-year-old recalled.

With no sleeping bags available back then, he often had to huddle with shepherds in makeshift shelters they used when herding their livestock.

But he added that there was no guarantee the cozy sleeping arrangement would keep him warm from the elements.

"A fire was lit in the shabby cabin but the cold air kept penetrating inside," he said. "I felt like a hot brick on one side and bitterly cold on the other. I had to turn my body over frequently as if I were a pie that was being cooked in an oven," said Yang, breaking into laughter.

Both food and accommodation improved after the 1990s as larger field expeditions were conducted.

There were porters to help transport the research teams' luggage and food supplies, such as dried beef and sweet potatoes. Despite the advances, there were still difficulties.