The 33-year-old reality TV star - who has two children, Mason, three, and Penelope, nine months, with her 30-year-old boyfriend - is eager to get back to her pre-pregnancy weight slowly by maintaining a healthy diet and regularly exercising but Scott thinks she should slim down quicker.
A source told InTouch magazine: ''Scott loves skinny women with big boobs. He wants Kourtney back to her pre-baby weight. He's being shallow and downright mean.
''He ridicules her and makes fun of her.''
Scott was recently seen making comments about Kourtney's weight on their E! reality series 'Kourtney & Kim Take Miami' as he tried to encourage her to drop a few more pounds.
He said: ''Last time around you tried to watch what you were eating, after you had Mason... at least you were losing weight. Just do it faster -- you're my piece of machinery!
''If I would have fell in love with you a couple of pounds overweight, this would be my ideal weight, but I fell in love with you when you were super skinny.''
The reality star was unapologetic about his approach, and recently wrote on Twitter: ''Never realised how upset people get when a person makes a comment about weight.
''P.s anyone who has to much to say probably had to much to eat. #fatasses (sic).''
Kourtney famously collapsed while she was trying to shed her baby weight the first time around because she was so obsessed with slimming.