I'm a 42-year-old pregnant nutritionist. I eat plenty of protein, love spicy foods, and snack on nuts.

• Melissa Pfeister, 42, is pregnant with her third child. 
• She's also a Stanford Medicine certified nutritionist.
• She says that nutrition can't always be perfect during pregnancy. 

This as-told-to essay is based on a conversation with Melissa Pfeister. It has been edited for length and clarity.

This is my third pregnancy (if you don't include my many miscarriages) but my first after completing a nutrition course from Stanford Medicine. I always had a passion for health and fitness, but this time, I felt even more empowered with knowledge about how to eat healthy during pregnancy.

Then, it all went out the window because I was so sick during the first trimester. It was absolute survival mode. I was vomiting a lot and going to the emergency room because I was so dehydrated. I gave myself permission to eat anything that I could — even if it was a burger or chicken nuggets from McDonald's.

I feel a lot better now that I'm approaching the third trimester. And I understand that even with the best-laid plans, life sometimes gets in the way. You have to learn how to roll with those punches.

I focus on healthy foods that are easy to make

I make sure that I eat plenty of filling foods with a lot of flavor each day. One of my favorite tricks is using salsa to add flavor to dishes. Another secret weapon of mine is sriracha. Even during pregnancy, the more spice, the better for me.

Although I'm health-conscious, I'm also tired. Not only am I pregnant at 42, but I'm chasing after my two other children, who are 5 and 6. Cooking and cleaning feels like a chore, so I rely on batch meals when I can. I cook large pots of turkey chili and roast huge batches of vegetables that I can eat for the next two or three days.

Breakfast is typically eggs or oatmeal

Mornings are busy, so I always make a breakfast that the kids will eat, too. Usually, that's something like eggs or oatmeal.

If I'm eating eggs, I'll combine 2-3 egg whites with one whole egg to load up on plenty of protein. I love to eat that with whole-wheat bread or an herb tortilla wrap to add fiber. If I'm having a wrap, I pack it with tons of arugula to get my greens and vitamins in and top it with spicy sriracha.

Another favorite is plain oats flavored with almond butter, unsweetened almond milk, and cinnamon. I pack that with fruit, like berries and bananas, to get a healthy dose of nutrients.

I make sure to get healthy fats in snacks and at lunchtime

My go-to lunch is avocado toast. Avocados are full of heart-healthy fats. I layer them on whole-wheat toast, topped with tomatoes and greens. I also add chili flakes. Spice gets your metabolism pumping and encourages you to drink more water, which is especially key during pregnancy.

If I'm hungry during the day, you'll find me reaching for nuts. Almonds and walnuts are my favorite. They are amazing sources of healthy omega fatty acids and fats. I incorporate vegetables, too, whether carrots and celery or leftover roasted vegetables from the night before. I'm also a huge fan of edamame, another great protein and fiber source.

Along with the snacks, I drink tons of water and unsweetened iced tea during the day. I always have a big pitcher of iced green tea flavored with mint, lemon slices, or even watermelon. It's fun and refreshing.

I want to have a fulfilling relationship with food

My dinner usually consists of lean protein, like baked chicken breast, and tons of vegetables to give my body all the vitamins and nutrients it needs. Often, I eat a wrap here, too — it's just such an easy and delicious way to incorporate protein, vegetables, and whole-wheat carbs.

Like lots of people, I sometimes like a sweet treat for dessert. One of my favorites is fat-free Cool Whip with chocolate protein powder mixed in. Or, if I'm in more of a cookies-n-cream mood, I'll crumble a FiberOne brownie into the Cool Whip, mix it together, then stick the Cool Whip back into the freezer for a bit. When it's chilled, you'll have the best chocolate or cookies-n-cream ice cream without as many calories.

I never want food to be bland or boring. It's important to me to have a fulfilling relationship with food, and I enjoy finding ways to make healthy dishes that also taste great. There are always options.