Nattawut Jantaweemol (Thai: ณัฐวุฒิ จันทรวิมล, born 11 November 1968), later Muangchai Jantaweemol (Thai: เมืองชัย จันทรวิมล), known professionally as Muangchai Kittikasem (Thai: เมืองชัย กิตติเกษม), is a Thai former professional boxer who competed between 1988 and 1999. He is the first Thai to be a world champion in two weight classes, having held the IBF junior-flyweight title from 1989 to 1990 and the WBC and lineal flyweight title from 1991 to 1992.

Kittikasem claims to have fought around forty to fifty Muay Thai fights, using the ring names Jingjok Uvichaiyont (Thai: จิ้งจก อู่วิชัยยนต์) and Muangchai Singnonsuan (Thai: เมืองชัย สิงห์โนนสวน) but never won any championships. He changed to boxing when a promoter needed a short-term replacement on one of his cards. In professional boxing, he had three managers were Kitti Akkraseranee, Song Karnchanachoosak and Songchai Rattanasuban.

The relentless pressure fighter Kittikasem started to fight professionally in 1988. In only his 7th bout 1989 he won the IBF junior-flyweight title on points against Filipino Tacy Macalos and defended it against the same fighter by KO. After two defenses, he went to the United States to defend the crown against undefeated amateur star Michael Carbajal in 1990. In the bout, he was knocked down four times by the American and injured his chin during the 7th round.^[1] His chin became his major weakness since then.

He went up in weight and won the WBC and lineal flyweight title by KO in a 6-round fight against his countryman Sot Chitalada the very next year. Kittikasem KOd Jung Koo Chang and stopped Chitalada once again in the rematch.

He lost another title to another amateur world champion, Russian Yuri Arbachakov, in 1992. The fight took place in Japan, and ended in an explosive KO when Kittikasem ran right in a counter. In 1993, he was KO'd one more time by Arbachakov, this time in Thailand.^[2]

He had a couple more fights but never contended again.

After retiring from boxing, he ran a used car dealership in Thawi Watthana District, suburb Bangkok until 2011 when it was flooded. These days he is a local politician in Bang Bon District under the Pheu Thai Party, he had previously run for local elections in Bangkok twice but was not successful.

He is divorced and has two children. Kittikasem hailed Carbajal as the best opponent he had ever faced.^[3]

• Lineal championship
• List of world light-flyweight boxing champions
• List of world flyweight boxing champions