An excerpt from: 
As anyone who has ever experienced it will tell you, morning sickness is quite a misnomer. The symptoms often last all day long, sometimes increasing as the day goes on, with hunger and fatigue being fierce aggravators…

It seems cruel that when you’re sick and the breadth of your diet will start at saltines and end at dry toast; nutrition is needed now more than possibly ever. As long as you’re eating something, you and the baby will be ok. You should be taking prenatal vitamins, or a doctor-approved multi-vitamin. These supplements will fill in the nutritional gaps for the few weeks that your taste buds are out of whack.

Before getting pregnant I ate relatively healthful foods. I kept my meals nutritious and well balanced and indulged my sweet tooth with snacks. But once morning sickness kicked in, it was crackers or dry cereal in bed, and whatever I could stomach for the rest of the day. Yogurt, salad, chicken, and most fruits and vegetables—normally my staples—were nausea-inducing. Soft pretzels, bagels, crackers, and popcorn filled in my otherwise empty diet.

But girl cannot live on carbs alone (sad but true). Luckily, as the morning sickness passed with my first trimester, so did the health food aversions. Fruit, meat and vegetables were soon incorporated back into my meal plan. A banana now accompanied the English muffin, and chicken filled part of my pasta dish…

There’s an old adage about eating for two. While it is very important that you increase your food intake, preferably with healthful foods, it’s not necessary to double up. Adding nutritious snacks and moderately increasing your portion size should be sufficient. Your doctor will monitor your weight and the size of the baby. Don’t stress over the numbers on the scale or the size of your maternity jeans…