First, I have never heard of any doctor telling a pregnant woman to diet or lose weight. You should expect to gain between 20-30 pounds during pregnancy. Just because you gain weight during pregnancy doesn't mean you will have a fat baby. That is a complete fallacy.Second, having a well balanced, nutritious diet is key. Eating plenty of whole grains, fruits, vegetables, lean proteins, staying hydrated, and not starving yourself is most important. Do not skip meals! Your baby will take the nutrients it needs from your body, and if you are not restoring those nutrients you will become deficient. This will in turn starve your baby of the nutrients it needs.Third, walking during pregnancy is a great form of low-impact exercise. Miscarriage is highly unlikely, unless you have previous issues and your doctor has told you to not walk. Another fun way to get a good, low impact workout is prenatal yoga. It is great for stretching, energy, and toning muscle (by the way, building muscle burns fat more effectively than dieting). Yoga is also relaxing and helps the body prepare for childbirth. Just get a dvd from any store and do it at home when you have time.Finally, your body is doing an amazing thing, growing a beautiful bundle of joy! The job you have is creating a healthy environment for your child, inside of you. Take every pound and celebrate it! You will have plenty of time after having the baby to lose the weight.Like you I am a size 16 at my thinnest. With each of my four pregnancies I gained 25 pounds, wearing a size 20 postnatal. The weight will go away. Just enjoy this time where you have a perfectly viable reason to not diet. Perhaps, if you are still not happy, find a different nutritionist. One who works specifically with pregnant women.