一口吃不成胖子 [－－－－－－－]

Jyutping jat1 hau2 hek3 bat1 sing4 bun6 zi2
Pinyin yī kǒu chī bù chéng pàng zi

Definitions (CC-CEDICT)
  1. lit. you cannot get fat with only one mouthful (proverb)
  2. fig. learn to walk before you run