15 weeks gyno visit

So today I had my 15 week gyno visit. the gyno wants me to eat more healthier because i gain 4 kilos after my last visit. i cant drink any juices, no sweets and less carbs. please help any suggestions. shes afraid my diabetes level will arise and which wont be so healthy for the baby. i may only eat a treat once a week. :( heard thr baby heartbeat today..my heart melted. i just want a healthy baby so im going to try eating healthier. any advise or suggestions and eating healthy habits.