Photographer Gregg Segal travelled the world to document children and the food they eat in a week. Partly inspired by the increasing problems of childhood obesity, he tracked traditional regional diets as yet unaffected by globalisation, and ironically, found that the healthiest diets were often eaten by the least well off. (Photo by Gregg Segal/The Guardian)

Model Heidi Klum and TV personality Nick Cannon speak onstage during Nickelodeon's 24th Annual Kids' Choice Awards at Galen Center on April 2, 2011 in Los Angeles, California. (Photo by Kevork Djansezian/Getty Images)

Labourers who work nearby nap on a road as cars drive past in Chongqing Municipality, July 23, 2013. (Photo by Reuters/Stringer)

Tao Xiangli gets out of his homemade submarine after operating it in a lake on the outskirts of Beijing September 3, 2009. Amateur inventor Tao, 34, made a fully functional submarine, which has a periscope, depth control tanks, electric motors, manometer, and two propellers, from old oil barrels and tools which he bought at a second-hand market. He took 2 years to invent and test the submarine which costs 30,000 yuan ($4,385). (Photo by Christina Hu/Reuters)

A performer practices her mermaid swim next to a shark in an aquarium after graduating from a mermaid workshop in Guangzhou, Guangdong Province, China December 16, 2016. (Photo by Tyrone Siu/Reuters)

Passengers wait for a train to depart from the Hankou Railway Station in Wuhan, central China's Hubei province, Friday January 13, 2017. Officials expect that Chinese travelers will make almost 3 billion trips during the holiday travel rush that starts runs through Feb. 21. These trips include intercity flights, trains and local bus rides to villages for China's 1.4 billion people. (Photo by Chinatopix via AP Photo)

A model walks down the runway at the 13th China International Young Fashion Designers Contest during China Fashion Week on March 25, 2005 in Beijing, China. (Photo by China Photos/Getty Images)

Yu Jietao, 26-year-old wood carver, sits in his homemade wooden car along a street in Guangfeng county of Shangrao, Jiangxi province, China February 9, 2015. The car can travel as fast as 30 km (18.6 miles) per hour, local media reported. (Photo by Reuters/Stringer)