Yes, yes. We have all heard it. “Have another piece of cake. You are eating for TWO.”
Egads. Back in my mom’s day, women didn’t gain much weight with pregnancy. 15 pounds was likely normal. I know a woman who was told by her doctor (remember this is a long time ago…) to start smoking (!!) as she was gaining too much weight with one of her pregnancies.
You don’t need many extra calories for your little bun in the oven. According to a nutritionist, you need more nutrients during pregnancy, but not more calories. In the first trimester you need no extra calories. In the second trimester you should have an extra 350 cals/day, and in the third 450 cals/day.
Which nutrients? Protein (recommendation is an extra 20g/day), folate (extra 50% of normal rec), iron (50% more than normal, so about 27mg/day total), and zinc. Don’t take any supplements though without checking with a doctor or registered dietitian because too much of certain vitamins is bad.
As far as weight gain, according to guidelines, you should gain 25-35 pounds if you are a normal “healthy” weight when you begin your pregnancy. If you are 5’6″, to be at a healthy weight when you start means you should weigh 118-148 pounds. If you weigh over 150 pounds you are “overweight.” If you weigh 186 pounds you are obese.
See my blog on BMI and weight gain recommendations by the IOM.