The average breastfeeding woman needs about 450 to 500 additional calories per day. If you’re working out, that daily requirement could jump to 3,000 calories or more, estimates Lane.
“The energy you’re getting from extra calories supports exercise, recovery, and milk production,” explains D. Enette Larson-Meyer, Ph.D., RD, CSSD, professor of human nutrition and director of the nutrition and exercise laboratory at the University of Wyoming in Laramie.
What to do: Add 450 to 500 calories a day to what you normally eat and listen to your hunger cues, says Krista Austin, Ph.D., CSCS, a San Diego-based performance and nutrition coach.
Since the nutrients in your diet find their way into your milk, eating high-quality foods should be top of mind. Prioritize healthy fats over protein and carbs, since they have the most calories (nine) per gram, Lane says. While breastfeeding, you may need as much as 20 to 30 extra grams per day. That’s about one small avocado, three or four tablespoons of peanut butter, or 1.5 to two ounces of mixed nuts.
Newborns may eat every four hours or more often. If you go too long between pumping or feeding, your breasts may start to feel uncomfortably full, so you'll need to time exercise accordingly.
What to do: Nurse or pump both breasts right before a workout, then keep track of how much time passes before your baby needs to eat again. If you’re going to be away for longer periods of time (anywhere from two to five hours, depending on his or her age), consider a wireless pump for on-the-go access.
Your body draws calcium from your own bones to make milk when you're breastfeeding, reducing bone density by about five percent, Larson-Meyer says. The drop is too severe to avoid by eating calcium, but it's nothing to be concerned about; most studies show bone density returns to pre-pregnancy levels once you're done lactating.
It does, however, mean you need to be careful about progressing your workouts too fast, too soon, which will up your risk of a stress fracture.
What to do: Increase your activity levels by no more than 10 percent week over week, Larson-Meyer notes. For example, if you run five miles your first week back, you wouldn’t want to go more than 5.5 miles week two. If you use 20-pound weights on your strength day, you shouldn't go beyond 22 pounds the next week.
Thyroid hormones are key for creating breastmilk and thyroid health depends in part on iodine, so you’ll need to double your intake from 150 micrograms per day (the standard adult rec) to 290. Since there’s iodine in salt, you lose it when you sweat, making it crucial to replenish if you’re working out, Larson-Meyer says.
What to do: Eggs and fish are great sources of iodine but your best bet is iodized salt, with 71 micrograms per quarter teaspoon.
If you use it while cooking and to bring out the flavors in finished dishes, you're likely getting enough to meet your daily requirements—and satisfy those salt cravings, says Larson-Meyer.
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