The vest is consist of 3D patterns: Rib Collar, Spike Chest, and Bias Stockinette waist. It pushed chest up, and shrink the waist.

Knit
Purl
Purl 2 together
Purl 3 together
Make 1 stitch
Knit 2 together
Knit 3 together
Slip Slip Knit
Slip 2 stitches to right needle, knit next stitch on left needle, pass two slipped
stitches over the last knitted stitch (decrease 2sts.)
Knit front & Back (increase 1 sts.)