What do you think ?

So I went in yesterday for my 20 week appointment . Found out I'm having a baby girl everything was great from ultrasound found out she's weighing 13oz already and just so healthy and I'm so happy but my nurse told me that i need to slow down on the eating. Before I got pregnant I weighed 112 now I weigh 131 and I'm 20 weeks will be 21 Saturday. My sister told me that's crazy that I should still eat the same as long as the baby is healthy the better? Has anyone ever been told this.