Sporting a bright-red helmet and a jacket bearing a fork in the logo, Mr Xie Geng stands out in the sea of white coats and blue scrubs.
Yet, no one gives him a second glance on a busy weekday morning as he zips across Dongzhimen Hospital in central Beijing with a delivery bag slung over one shoulder.
"Baidu Waimai," he calls out, rapping on a neurologist's door.
He hands over three knotted bags of food and runs back to his electric bike. The next order has already popped up on his phone.
Mr Xie, 18, is among some 20,000 Baidu Waimai delivery riders in Beijing. He sends food, drinks and fresh produce to residents who are taking to online takeaway in droves because of deep discounts created by cheap labour, smartphones and intense rivalry.
CHINA'S ONLINE FOOD DELIVERY: FACTS & FIGURES
The sector's share of the pie in China's overall 5.14 trillion yuan (S$1.04 trillion) e-commerce market.
How much bigger it is than South-east Asia's entire e-commerce market last year.
Size of China's online-to-offline food delivery market last year, up 23 per cent from 2015. This is double the size of the United States' US$11 billion (S$15.3 billion) online food delivery market.
Number of people who ordered food online last year, up 85 per cent from 2015.
9 in 10
Proportion of people using the telephone to place the orders.
SOURCES: IIMEDIA RESEARCH, CHINA INTERNET NETWORK INFORMATION CENTRE
Last year saw over 208.5 million people order food online, an 85 per cent jump from 2015, according to the semi-official China Internet Network Information Centre.
One reason is the cutthroat competition among industry players with deep pockets. They have been burning cash and subsidising orders to build market share. Baidu Waimai, for instance, belongs to search giant Baidu.
Mr Xie fills his first order at 8am, but it is during the lunchtime peak period starting at 11am that things get frenetic.
"Most deliveries are to offices, for workers too busy to come out for lunch," says the Jiangsu native. "Some are to homes where people don't feel like cooking."
Be it pad thai, kimbap or raw pork, he picks it up and sends it to office blocks and hutong (ancient alleyways) in north-eastern Beijing's urban core.
The breakneck pace means that by the time things start to wind down at 3pm, Mr Xie has already filled 13 orders.
Even so, at 4 yuan (80 Singapore cents) per order, he has made barely enough to pay for one of the meals he has delivered. He is eligible for a daily basic wage of 100 yuan, but only if he fills at least 15 orders for the day or puts in a full 10 hours.
In all, this works out to a salary of about 5,000 yuan a month, half of which goes to rent, food and paying off his electric bike.
"I came here last month with 2,000 yuan, but it wasn't enough, and I had to borrow 3,000 yuan from friends and family," he said. "Money is tight but I hope things will get better."
Like the seven other deliverymen with whom he shares a one-room apartment, he grabs a quick lunch and nap before swopping out his bike battery for the evening dinner rush.
When he logs back on to the app at 5pm, a ding signals a new order, and he is back on the road.
VIDEO: Breakneck pace for food deliverymen in Beijing