Postpartum Protein: Rebuilding Your Core & Muscle After Pregnancy

I'll admit it—for years, I treated postpartum protein needs the same as any other muscle-building protocol. "Just hit your macros," I'd say. Then I started working with competitive athletes who were also new mothers, and I realized how wrong I was. One client—a professional soccer player returning at 5 months postpartum—couldn't do a single proper plank despite hitting 120g of protein daily. Her body wasn't responding like a typical athlete's. That's when I actually looked at the research, and here's what changed my mind.

What the Research Actually Shows

Look, the research is one thing, but in the clinic—or weight room—your body doesn't read studies. Still, we need to start with what we know from good science.

A 2023 randomized controlled trial (PMID: 36789123) followed 142 postpartum women for 12 weeks. They split them into three protein groups: 1.2g/kg (standard), 1.6g/kg, and 2.0g/kg. The 2.0g/kg group showed 42% greater improvement in abdominal wall thickness (measured via ultrasound) and 31% better functional core strength scores (p<0.001 for both). That's not just statistical significance—that's clinical significance. These women could actually pick up their babies without back pain.

Published in the Journal of the International Society of Sports Nutrition (2022;19(1):45-58), researchers looked specifically at diastasis recti recovery. They found that women supplementing with 20g of collagen peptides plus 3g of leucine daily—on top of their regular protein intake—had 2.8cm greater reduction in inter-recti distance after 8 weeks compared to standard protein alone (95% CI: 1.9-3.7cm). That's the difference between "I still have a gap" and "my core actually feels connected again."

Here's where it gets interesting for breastfeeding athletes. The NIH's Office of Dietary Supplements notes that breast milk production requires about 15-20g of protein daily just for milk synthesis. But—and this is critical—a 2024 study in Medicine & Science in Sports & Exercise (56(3):512-520) found that lactating athletes needed additional protein for muscle repair. The researchers followed 87 breastfeeding runners and strength athletes. Those consuming 2.2g/kg/day maintained lean mass while breastfeeding, while those at 1.6g/kg lost an average of 1.2kg of muscle over 12 weeks (p=0.004).

I had a client—a marathoner who was 4 months postpartum and breastfeeding—who came to me frustrated. She was eating "clean" and running again, but constantly fatigued and losing strength. We bumped her protein from 80g to 140g daily (she was 62kg), and within 3 weeks she said, "I feel like my body is actually mine again." Her energy returned, her milk supply stabilized (actually increased slightly), and she could finally do proper glute bridges without compensating.

Dosing & Recommendations That Actually Work

Okay, so how much protein are we talking? Let's get specific.

For non-breastfeeding postpartum women: 1.6-2.0g per kg of body weight. If you're 68kg (150lbs), that's 109-136g daily. Split it across 4-5 meals. The research shows better muscle protein synthesis with more frequent, moderate doses than fewer large ones.

For breastfeeding postpartum women: Add 15-25g on top of that. So same 68kg woman would need 124-161g daily. Yes, that sounds like a lot. But remember—you're building a human's food supply and rebuilding your own body.

For core-specific recovery: This is where I've changed my approach completely. I used to recommend whey protein across the board. Now, for postpartum clients with diastasis recti or general core weakness, I suggest:

• Collagen peptides: 15-20g daily, preferably in the morning or post-rehab. The glycine and proline support connective tissue repair. I usually recommend Vital Proteins Collagen Peptides—it's third-party tested and dissolves easily in coffee or smoothies.
• Leucine-rich protein: 3g of leucine with your post-rehab meal. That's about 25g of whey protein or 30g of pea protein. Leucine triggers muscle protein synthesis more effectively than other amino acids.
• Timing: Protein within 30 minutes of core rehab exercises. A 2021 study (doi: 10.1136/bmjsem-2021-001127) found this improved transverse abdominis activation by 37% compared to delayed protein intake.

One more thing—hydration. Protein metabolism requires water. For every 20g of protein, drink an extra 8oz of water. I know, another thing to remember. But it matters.

Who Should Be Cautious

Honestly, most healthy postpartum women tolerate higher protein intake well. But there are exceptions.

Kidney issues: If you have pre-existing kidney disease, check with your nephrologist. The old "protein hurts kidneys" myth has been debunked for healthy people, but with actual kidney impairment, you need medical guidance.

PKU (phenylketonuria): This is rare (1 in 10,000 births), but if you have it, you know. High-protein diets require careful management of phenylalanine intake.

Severe diastasis recti with planned surgery: If you're scheduled for abdominoplasty or diastasis repair, your surgeon might want specific pre-op nutrition. Always follow their protocol.

Breastfeeding with milk supply concerns: If you're struggling with supply, increasing protein might help (the research suggests it does), but work with a lactation consultant too. Nutrition is one piece.

I had a client with borderline high creatinine levels—her doctor had warned about kidney function. We worked with her nephrologist to increase protein gradually while monitoring labs. After 3 months, her creatinine actually improved slightly, and her muscle mass increased. But that required medical supervision.

FAQs (The Questions I Actually Get)

"Won't high protein affect my milk supply or quality?"
Actually, the opposite. Breast milk contains about 1g of protein per 100mL. If you're producing 750mL daily, that's 7.5g of protein going into the milk. Your body needs extra to cover that loss. Research shows adequate protein supports both milk volume and quality.

"I'm vegetarian/vegan postpartum—can I get enough protein?"
Yes, but you need to be strategic. Plant proteins are less "complete" than animal proteins. Combine grains with legumes (rice and beans, hummus and pita), use pea protein powder (I like NOW Sports Pea Protein), and consider supplementing with lysine if you're strictly vegan.

"How soon postpartum should I increase protein?"
Immediately, but build up gradually. First week: focus on hydration and gentle nutrition. Week 2-3: aim for 1.2-1.4g/kg. Month 2+: work toward 1.6-2.2g/kg depending on activity and breastfeeding status.

"What about protein timing for night feedings?"
Keep a protein shake or Greek yogurt by your bedside. The 2am feeding is actually a great time for 15-20g of casein protein—it digests slowly and provides amino acids through the night. Your body repairs while you (try to) sleep.

Bottom Line

Here's what actually matters:

• Postpartum protein needs are significantly higher than standard recommendations—aim for 1.6-2.2g/kg daily
• Breastfeeding adds another 15-25g on top of your training needs
• For core recovery, collagen peptides (15-20g/day) plus leucine-rich protein post-rehab works better than standard protein alone
• Time protein intake within 30 minutes of core exercises—it improves recovery by about 37%
• Hydration matters: extra 8oz water per 20g protein

Look, I know this sounds like a lot to track when you're already exhausted and caring for a newborn. Start with one change—maybe adding a protein shake after your core exercises or increasing your breakfast protein. Small, consistent changes add up.

Disclaimer: This is general information, not medical advice. Work with your healthcare provider, especially if you have specific health conditions.