Episode 269 | Feed the Rebuild: What ACL Athletes Get Wrong About Nutrition

Welcome back to another episode of the ACL Athlete Podcast. My voice is a little off again—I seem to be on a cycle of recording while sick, thanks to my kids bringing home whatever is going around. It comes with the territory, especially with a toddler in preschool, so I’m doing my best to push through. Hopefully, as we head into spring and summer, there’s a bit less illness in the mix. But for now, we’re here, and we’re diving into an important topic: nutrition. Specifically, what happens when you undereat after surgery, and why the instinct to cut calories might be one of the most costly mistakes you can make during ACL recovery.

Before we go further, I want to be clear about my scope. I am not a registered dietitian, and I’m not here to prescribe exact macros or detailed meal plans. If you need personalized nutrition guidance, working with a registered dietitian is absolutely the right move. I’ve collaborated with dietitians and even had them on the podcast, and they are invaluable resources for this level of specificity. My goal today is to speak from research and clinical experience in the health and performance space, and to help you understand the bigger picture. This is about awareness, not prescription.

One of the most common things I hear from athletes after surgery is this: “I’m not doing anything right now, so I don’t need to eat as much.” They’re on the couch, not training, and far less active than before, so it feels logical to reduce calorie intake. There’s also the concern about gaining weight, which can be especially sensitive for athletes who already feel self-conscious about body composition. This concern spans across all types of athletes, regardless of gender, and it’s something I’ve seen repeatedly in practice. Even personally, having grown up as a heavier kid, this was something that crossed my mind during my own ACL surgeries.

I recently had a conversation with a male athlete who was preparing for surgery and planning to cut his macros significantly. His reasoning was straightforward: he’d be less active and wanted to lose weight. His surgeon even supported that idea. But I disagreed, because the focus was misplaced. The conversation wasn’t centered on what the body actually needs during the rebuilding process. This is where context matters, and it’s something I’ve discussed with registered dietitians as well—how to balance muscle retention, recovery, and adequate fueling during this critical window.

While the instinct to eat less might feel logical, it doesn’t reflect what your body is actually going through. Even if you’re physically inactive, your body is working overtime behind the scenes. It’s managing inflammation, healing surgical tissues, integrating a graft into bone, and trying to preserve muscle mass that is rapidly declining. All of this requires energy. Food, in this context, is not just intake—it’s fuel. Reframing nutrition this way is essential because when you cut off that fuel, you’re not maintaining the status quo; you’re actively working against your recovery.

After surgery, your body enters what’s known as a surgical stress response. Hormones like cortisol and glucagon increase, driving your body into a catabolic state. This means it begins breaking down tissue to support wound healing, immune function, and blood glucose regulation. One of the primary sources it pulls from is skeletal muscle. At the same time, insulin sensitivity decreases, which reduces your body’s ability to stimulate muscle protein synthesis—the very process needed to rebuild and retain muscle. In simple terms, breakdown goes up while rebuilding goes down, and that imbalance defines the early post-operative state.

The data here is sobering. A 2021 review published in Nutrients found that healthy young men experienced a 1.7% loss in total thigh muscle volume after just two days of disuse, and up to 5.5% after seven days, with the quadriceps taking the biggest hit. That first week after ACL surgery—when you’re resting, icing, elevating, and beginning early rehab—is also when muscle loss accelerates. At the same time, many athletes are eating less because they believe they’re not burning as many calories. In reality, this is one of the most metabolically demanding periods your body will face, and it requires sufficient raw materials to support recovery.

The same review also found that surgical patients typically consume only 22% to 36% of their estimated protein needs post-operatively. That’s less than a third of what the body requires. This gap has real consequences: increased muscle atrophy, delayed tissue healing, and slower progress through rehab milestones. Despite this, athletes often don’t connect their nutrition to these outcomes. They feel the effects—poor quad activation, low energy in physical therapy, stalled progress—but attribute them to the injury itself or the rehab protocol, rather than inadequate fueling.

This disconnect is one of the most frustrating parts of the process. Early post-op recovery is already complex, with pain, swelling, and limited mobility clouding the picture. It becomes difficult to isolate variables, and nutrition often gets overlooked. However, in practice, we consistently see that underfueling has a measurable impact on strength, energy levels, and muscle retention. Even when athletes are doing everything else right, insufficient nutrition can quietly undermine their progress.

The key takeaway here is simple and actionable. First, avoid restricting calories in the early post-operative phase. Your metabolic rate doesn’t suddenly drop to zero because you’re not training. Healing itself is energetically expensive, and your body is working hard behind the scenes. While some adjustments may be reasonable if your activity level has significantly changed, extreme restrictions will only set you back. The goal is not to swing the pendulum in the opposite direction but to provide steady, adequate fuel for recovery.

Second, prioritize protein at every meal. Protein is a foundational component of muscle repair and rebuilding, and your needs increase after surgery. A practical rule of thumb is to aim for approximately one gram of protein per pound of body weight per day. For a 150-pound athlete, that’s about 150 grams of protein daily. While research often suggests ranges of 1.5 to 2.0 grams per kilogram of body weight, this simplified approach is effective and widely supported. For most people, this is significantly more protein than they’re currently consuming.

Meeting that target can be challenging, so focus on consistency and practicality. Lean meats, eggs, fish, Greek yogurt, and cottage cheese are excellent options. If you’re falling short, protein supplements such as shakes or bars are useful tools to help close the gap. Trying to meet your entire protein requirement through whole food alone can be unrealistic, so using supplements strategically can make a big difference. Increased protein intake also supports satiety, helping you feel fuller for longer and maintain better overall nutrition habits.

Third, if you’re unsure about your intake, seek guidance. A registered dietitian is the best resource for personalized nutrition strategies, but your coach or clinician can also provide direction. The difference between adequate and inadequate nutrition during recovery is not subtle—it directly impacts muscle size, strength, and readiness for return to sport. I’ve seen athletes make significant progress simply by improving their nutrition, especially when other factors like training, sleep, and stress management are already in place.

In our work, we look at recovery holistically. Movement and exercise are just one piece of the puzzle. Nutrition, sleep, stress management, and social support all play critical roles in performance and healing. Ignoring these areas while focusing solely on rehab exercises limits your potential. When athletes begin to address these foundational elements, particularly nutrition, the improvements can be substantial.

Ultimately, your goal in the weeks following surgery is not to stay lean. That is not the priority right now. The objective is to give your body everything it needs to heal, rebuild, and perform when it matters most. Body composition can be addressed later, once you’ve established a strong foundation. Underfueling during recovery doesn’t preserve progress—it costs you muscle, delays your timeline, and reduces your overall outcomes. Feed the recovery. That is your job right now, so make sure you do that. Thank you so much for reading and being here. If this resonated with you, consider sharing it with someone who might need to hear it. It doesn’t have to be an ACL athlete—this applies to anyone recovering from surgery or a serious injury.

If you’re looking for more guidance or want to work directly with our team, check out the website or explore the show notes where you’ll find more information. And if you simply need direction or support, don’t hesitate to reach out—we’re here to help. We’ll see you next week on the ACL Athlete Podcast. 

This is your host, Ravi Patel, signing off.