Nutrition Before Knee Replacement: Prepare, Heal, and Recover Stronger
Medically reviewed by Dr. Patrick Denard, orthopaedic surgeon, on October 8, 2026
Short answer: start about 1 week before your knee replacement. Get enough protein every day, because your quadriceps (the big muscle on the front of your thigh) can weaken and shrink quickly after surgery. A daily protein shake makes that easier. Ask your surgical team whether you can have a carbohydrate drink the night before instead of fasting from midnight. Then keep the protein going through the first 6 weeks of rehab. [1]
This guide covers why that matters, what the research found, and what to do in each phase. For a closer look at individual products, read our guide to the best supplements after knee replacement surgery. For meal ideas and a daily protein target worked out for your weight, see what to eat after knee replacement surgery.
What Knee Replacement Asks of Your Body
A knee replacement is a major operation, and your body responds to it like one, with inflammation, energy demands, and tissue repair all happening at once. Two challenges stand out for knee patients.
Your quadriceps takes a hit. The big muscle on the front of your thigh is what straightens your knee, stabilizes you, and gets you up from a chair. After knee replacement, that muscle can weaken and shrink quickly, and rebuilding it is the central work of your rehab. Protecting it from the start makes everything that follows easier.
Your body has to defend against infection while it heals. Like any joint replacement, a knee replacement carries a small risk of infection, and your nutritional status is one of the factors that influences how well your body guards against it.
The encouraging part: both of these are areas where preparation helps. Nutritional gaps are common, often silent, and preventable. By giving your body the right nutrients at the right time, you can protect your strength and support the healing your new knee depends on.
What the Evidence Says About Nutrition and Knee Replacement
This isn't general wellness advice: it's published research on knee replacement, much of it from randomized controlled trials.
Protein and amino acids protect the muscle you'll rebuild in rehab.
In a randomized, placebo-controlled trial of 39 knee replacement patients, those who took 20 g of essential amino acids twice daily for a week before and six weeks after surgery lost less quadriceps muscle volume than those on placebo (a decline of about 8.5% vs. 13.4%). Muscle size was the clear result; strength and function tests ended up about the same in both groups. (Dreyer et al., JBJS Open Access, 2018) [1] In another randomized trial, patients given essential amino acids around surgery had greater quadriceps strength and muscle size two years later, although clinical outcome scores did not differ between groups. (Ueyama et al., JBJS, 2023) [2] In a third, small study of 23 patients, a group given an HMB, arginine and glutamine supplement kept their quadriceps strength two weeks after surgery, while the control group lost about 36%. (Nishizaki et al., Asia Pac J Clin Nutr, 2015) [3] None of these trials tested a Thrive product, and the doses were different from a daily OptiFuel packet. Our article on protecting muscle after joint replacement goes deeper on weak legs and quad loss.
Malnutrition is linked to higher infection risk.
A meta-analysis of 9 studies found that malnutrition was associated with about 2.6 times higher odds of surgical site infection and 3.4 times higher odds of deep joint infection after joint replacement. These are associations, not proof that a supplement lowers infection risk. (Chen et al., J Orthop Surg Res, 2024) [4]
Carbohydrate drinks around surgery have been studied in knee replacement.
In a retrospective, propensity-matched study of 156 knee replacement patients, a carbohydrate drink taken right after surgery (instead of plain water) was associated with better quality-of-recovery scores, less hunger and anxiety, lower insulin resistance, and a shorter stay. (Zhang et al., BMC Anesthesiol, 2025) [5] In a randomized trial of people with non-insulin-dependent type 2 diabetes, a carbohydrate drink 2 to 4 hours before knee replacement was safe, reduced pre-op hunger, and lowered insulin resistance after surgery. (Lai et al., J Arthroplasty, 2025) [6] Our guide to carb loading drinks before surgery explains how to choose one and when to drink it.
Vitamin C has been studied after knee replacement.
Results are mixed but interesting. In one randomized trial, vitamin C kept blood vitamin C levels from dropping after surgery, and fewer patients developed stiffness (10% vs. 23%), though that difference was not statistically significant. (Behrend et al., 2019) [7] In a prospective randomized study, 1 g of vitamin C a day for 40 days after surgery was associated with less complex regional pain syndrome, a painful nerve-related condition (3.9% vs. 12.2%). (Jacques et al., Int Orthop, 2021) [8] A retrospective matched analysis of 960 knee replacements found a similar pattern (6.9% vs. 11.0%). (Hernigou et al., JBJS, 2025) [9] Another randomized trial found less blood loss on the first day after surgery, with no difference in pain or function. (Hosseini-Monfared et al., Arthroplast Today, 2025) [10]
Vitamin D status affects your recovery.
In a systematic review of 10 studies covering about 150,000 knee replacements, vitamin D deficiency was associated with poorer outcomes, a meta-analysis of 3 studies linked it to longer hospital stays, and supplementation improved outcomes in 6 of the 10 studies. (Vivek et al., JBJS Rev, 2024) [11]
Collagen research is early.
Collagen is a key structural protein in tendons, ligaments and skin. A 2019 review of 11 small trials, mostly on skin, called the results for wound healing promising but preliminary (Choi et al., J Drugs Dermatol, 2019) [12], and a randomized trial in 50 healthy men found collagen peptides plus resistance training increased patellar tendon size more than training alone (Jerger et al., Eur J Sport Sci, 2023) [13]. Neither studied knee replacement.
The thread running through all of it: knee replacement is nutritionally demanding, the gaps are often invisible, and addressing them is something within your control.
The Protocol for Knee Replacement, Phase by Phase
Thrive Protocol organizes the evidence into one simple, phase-based system, developed by surgeons, with once-daily packets and clear timing. No guesswork, no shelf full of separate bottles.
Phase 1: Prepare (1 week before surgery)
OptiFuel delivers high-quality protein and essential amino acids, including leucine, so you can build up your protein intake before surgery and arrive strong rather than depleted. Each packet has 25 g of whey protein and 3 g of leucine. Take one a day between meals, mixed with 12 to 16 oz of water, milk or non-dairy milk. Before you start, share the ingredient list with your surgeon.
Phase 2: The Night Before Surgery
OptiCharge is your pre-op carbohydrate drink. If your surgical team approves, mix each of the 2 packets with 12 to 16 oz of water (never milk) and drink both at bedtime the night before surgery. Drinking a clear carbohydrate drink instead of fasting from midnight is part of many enhanced recovery programs; a Cochrane review of 27 trials found it was associated with a slightly shorter hospital stay (about a third of a day), based on very low-quality evidence. [17] (Always follow your surgical team's specific fasting instructions.) Wondering what else to eat that evening? Read what to eat the night before surgery.
Phase 3: Heal (the weeks after surgery)
Daily OptiFuel continues through the early recovery weeks, when your quadriceps is under the most pressure and your rehab is just beginning. Restart it once you are eating again after surgery. Alongside protein and amino acids to help maintain muscle, each serving includes vitamin C (which your body uses to make collagen), vitamin D (for normal bone and muscle function) and collagen peptides, so your nutrition is covered while you focus on physical therapy. It works alongside your surgeon's plan; it does not replace it.
Ships to your door before surgery day, with OptiCharge for the night before. HSA/FSA eligible. Already past surgery day? Start with the Recovery Protocol Kit instead.
Ideally, everyone on the Surgical Protocol Kit also takes the Recovery and Strength Mix daily.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
WANT TO GO FURTHER?
Add the Recovery and Strength Mix to your kit. It brings additional recovery amino acids, including arginine, plus creatine. It is the only Thrive product with creatine or arginine; OptiFuel has neither. Rebuilding quadriceps strength is the heart of knee replacement rehab, and creatine has been studied with strength training: in older adults, a meta-analysis found creatine plus resistance training led to greater gains in strength and lean mass than training alone [14], and in a small study of seven healthy young men with an arm in a cast, creatine was associated with less loss of muscle and strength [15]. Neither was a knee replacement study. The one small trial that did give creatine around knee replacement (37 patients, from 10 days before to 30 days after surgery) found no effect on strength, body composition or recovery at 30 days. [18] So think of creatine as a partner for the strength work later in rehab, not a shortcut in the first month. If you have kidney disease, ask your doctor first, and see what research says about creatine and your kidneys. A natural complement to OptiFuel, and easy to continue long after recovery.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Supplement safety before surgery
Thrive kits contain fish oil (omega-3s) and turmeric (curcumin) in low amounts. The evidence does not show that these amounts cause bleeding, so there is no need to stop OptiFuel before surgery. Your surgeon's instructions still come first. Tell your surgeon and anesthesia team about everything you take, including vitamins and herbal products. [16]
What to Expect: Your Knee Replacement Nutrition Timeline
Here is what the plan looks like from the day you order to the end of early rehab. The right-hand column sticks to what the studies above found, or to plain facts about the kit. No product can promise a faster recovery, and your surgical team's instructions come first at every step.
| When | What you do | What to expect |
|---|---|---|
| 2 to 3 weeks before | Order the kit and show the ingredient list to your surgeon. | Thrive's FAQ says delivery usually takes 5 to 10 business days, so pick expedited shipping if surgery is less than 2 weeks away. Each kit includes OptiFuel (28 packets per month), 2 OptiCharge packets and a shaker. |
| About 1 week before | One OptiFuel packet a day between meals, plus protein at each meal. | Each packet adds 25 g of whey protein. The amino acid trial above started a week before surgery, too. [1] This is a steady daily habit. You won't feel a change overnight, and that is normal. |
| Night before | If approved, 2 OptiCharge packets at bedtime, each in 12 to 16 oz of water. Then follow your fasting rules exactly. | In knee replacement studies, carbohydrate drinks were linked with less hunger. [5] [6] Across 27 trials, the hospital stay was only about a third of a day shorter, on very low-quality evidence. [17] Think of it as a comfort step, not a promise. |
| Surgery day and hospital stay | Follow your team. Nothing by mouth unless they say so. | Pain control, fluids and when you can eat are your team's call. The vitamin C studies above had mixed results and did not test this kit. [7] [8] [10] |
| Week 1 at home | Restart OptiFuel once you are eating again. Keep some protein at every meal, even small ones. | Your quad is under the most pressure now. In one small study, the group without a supplement lost about 36% of their quadriceps strength by two weeks. [3] That study used a different blend (OptiFuel has no HMB). OptiFuel is thin enough to sip through a straw, which helps when a full meal feels like too much. |
| Weeks 2 to 6 | OptiFuel between breakfast and lunch, Recovery and Strength Mix between lunch and dinner, and your physical therapy exercises. | In the 6-week amino acid trial, the supplement group lost less quad muscle (about 8.5% vs. 13.4%), but strength and function were similar by 6 weeks. [1] Physical therapy is what rebuilds strength. Protein gives it the raw material. |
| After 6 weeks | Keep the protein habit while you are still building strength. Your surgeon and therapist decide when you are back to normal activity. | Two years out, patients who took amino acids around surgery had more quad strength and muscle, though their clinical scores were similar. [2] The 3-month and 6-month kits cost less per day if you plan to continue. |
What it looks like day to day. One packet and the shaker that comes in the kit. OptiFuel mixes with water, milk or non-dairy milk, or blends into a smoothie. If plain shakes get boring by week 2, try these quick OptiFuel recipes.
| Product | Best for | Cost per day (prices checked 18 October 2026) |
|---|---|---|
| Surgical Protocol Kit | Surgery still ahead (OptiFuel plus OptiCharge) | 4-week: $299.99 / 28 = about $10.71. 3-month: $499.99 / 84 = about $5.95. 6-month: $669.99 / 168 = about $3.99. |
| Recovery Protocol Kit | Surgery already done (same OptiFuel, no OptiCharge) | 4-week: $289 / 28 = about $10.32 |
| Recovery and Strength Mix | Adding creatine and arginine to either kit | $49.99 / 30 = about $1.67 |
Thrive Protocol kits are HSA/FSA eligible, so you can use pre-tax health dollars. Want an honest look at how the kit stacks up against other options, including plain whey and a multivitamin? Read our Surgical Protocol Kit review.
Check with your doctor first if any of these apply
- Blood thinners. If you take one, tell your surgeon about every supplement you use, including the fish oil and turmeric in OptiFuel.
- Diabetes. For most people with diabetes the pre-op drink is fine, but if you use insulin, get your physician's approval before OptiCharge. If you skip it, the Recovery Protocol Kit is the same OptiFuel without OptiCharge.
- Kidney disease. If you have been told to limit protein, wait for your doctor's OK before adding a protein shake or the Recovery and Strength Mix.
- Milk allergy. OptiFuel is whey-based and contains milk. Thrive suggests the Recovery and Strength Mix alone for people who do not tolerate whey.
Your surgical team's instructions come first.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Built Into Your Recovery, Not Added On
Thrive Protocol was developed by surgeons to fill a real gap in surgical care, and it's designed to work hand-in-hand with the plan your surgical team already has for you. Surgery replaces your joint. Physical therapy rebuilds your strength. Nutrition gives your body the resources to make both succeed.
One packet a day. Mixed into water or a smoothie. Delivered before your surgery date.
You've got enough on your mind. Let the protocol handle the nutrition so you can focus on healing.
Frequently Asked Questions
When should I start nutrition before knee replacement?
Ideally about 1 week before your surgery date, with one OptiFuel packet a day. If your team approves, add the 2 OptiCharge packets at bedtime the night before. The muscle trials above started before surgery, and the protocol continues through the weeks after surgery, when muscle loss is fastest.
Why are my legs so weak after knee replacement?
Your quadriceps is the muscle that straightens your knee and gets you moving, and it weakens fast after knee replacement. Rebuilding it is the main job of rehab. Randomized trials found that essential amino acid supplements reduced that loss [1][2]; whether that speeds up rehab has not been proven, so keep doing your physical therapy.
Can I take creatine after knee replacement?
Ask your surgeon first, especially if you have kidney disease. In the one small trial of creatine around knee replacement, it did not improve strength or recovery in the first month. [18] In older adults doing strength training, creatine plus training led to greater strength gains than training alone. [14] At Thrive, creatine is only in the Recovery and Strength Mix, not in the kits.
Is carbohydrate loading safe if I'm diabetic?
One randomized trial in people with non-insulin-dependent type 2 diabetes found a carbohydrate drink 2 to 4 hours before knee replacement was safe and lowered insulin resistance after surgery. [6] Your surgical and diabetes team decide whether it is right for you, so follow their guidance on managing your diabetes around surgery. If you use insulin, get your physician's approval before OptiCharge.
My knee replacement already happened. Is it too late?
No. Start with the Recovery Protocol Kit, which is the same daily OptiFuel without OptiCharge (that drink is only for the night before surgery). Begin once you are eating again and keep going through rehab.
Can I use my HSA or FSA?
Yes. Thrive Protocol kits are HSA/FSA eligible, so you can use pre-tax health dollars.
Does this replace what my surgeon told me to do?
Never. Thrive Protocol works alongside your surgeon's instructions. Always follow your surgical team's guidance, especially their fasting instructions before surgery.
Protect Your Strength. Support Your New Knee. Recover With Confidence.
The weeks around your surgery are an opportunity, and the evidence says how you nourish your body during them matters. Give your recovery every advantage.
Developed by physicians. Made for the weeks around surgery.
Related guides
- What to eat after surgery: all procedure guides
- Supplements after knee replacement: what to take and when
- What to eat after knee arthroscopy or meniscus surgery
- Hip replacement nutrition guide
- ACL reconstruction nutrition guide
- Foot and ankle surgery nutrition guide
- Is creatine safe for your kidneys? What the research says
- Free surgery recovery guide
References
- Dreyer HC, et al. Essential Amino Acid Supplementation Mitigates Muscle Atrophy After Total Knee Arthroplasty: A Randomized, Double-Blind, Placebo-Controlled Trial. JB JS Open Access. 2018;3(2):e0006. pubmed.ncbi.nlm.nih.gov/30280129/
- Ueyama H, et al. Perioperative Essential Amino Acid Supplementation Facilitates Quadriceps Muscle Strength and Volume Recovery After TKA: A Double-Blinded Randomized Controlled Trial. J Bone Joint Surg Am. 2023;105(5):345-353. pubmed.ncbi.nlm.nih.gov/36856692/
- Nishizaki K, et al. Effects of supplementation with a combination of beta-hydroxy-beta-methyl butyrate, L-arginine, and L-glutamine on postoperative recovery of quadriceps muscle strength after total knee arthroplasty. Asia Pac J Clin Nutr. 2015;24(3):412-420. pubmed.ncbi.nlm.nih.gov/26420181/
- Chen Y, Chen W. Association between malnutrition status and total joint arthroplasty periprosthetic joint infection and surgical site infection: a systematic review meta-analysis. J Orthop Surg Res. 2024;19(1):660. pubmed.ncbi.nlm.nih.gov/39407322/
- Zhang L, et al. Effects of postoperative oral carbohydrate intake immediately on the quality of recovery: a propensity score-matched and multivariate analysis. BMC Anesthesiol. 2025;25(1):302. pubmed.ncbi.nlm.nih.gov/40596823/
- Lai Y, et al. Effect of Preoperative Carbohydrate Loading on Postoperative Recovery of Individuals Who Have Type 2 Diabetes After Total Knee Arthroplasty: A Randomized Controlled Trial. J Arthroplasty. 2025;40(3):665-671. pubmed.ncbi.nlm.nih.gov/39293701/
- Behrend H, et al. Vitamin C demand is increased after total knee arthroplasty: a double-blind placebo-controlled-randomized study. Knee Surg Sports Traumatol Arthrosc. 2019;27(4):1182-1188. pubmed.ncbi.nlm.nih.gov/29955932/
- Jacques H, et al. Prospective randomized study of the vitamin C effect on pain and complex pain regional syndrome after total knee arthroplasty. Int Orthop. 2021;45(5):1155-1162. pubmed.ncbi.nlm.nih.gov/33438072/
- Hernigou J, et al. Prophylaxis Against Complex Regional Pain Syndrome Recurrence with Vitamin C in Total Knee Arthroplasty: A Propensity Score-Matched Analysis of 960 Cases. J Bone Joint Surg Am. 2025;107(21):2352-2358. pubmed.ncbi.nlm.nih.gov/40924823/
- Hosseini-Monfared P, et al. Ascorbic Acid Reduces the Blood Loss After Total Knee Arthroplasty: Insights From a Randomized Controlled Trial. Arthroplast Today. 2025;32:101618. pubmed.ncbi.nlm.nih.gov/39974338/
- Vivek K, et al. Vitamin D Deficiency Leads to Poorer Health Outcomes and Greater Length of Stay After Total Knee Arthroplasty and Supplementation Improves Outcomes: A Systematic Review and Meta-Analysis. JBJS Rev. 2024;12(4):e23.00150. pubmed.ncbi.nlm.nih.gov/38574186/
- Choi FD, et al. Oral Collagen Supplementation: A Systematic Review of Dermatological Applications. J Drugs Dermatol. 2019;18(1):9-16. pubmed.ncbi.nlm.nih.gov/30681787/
- Jerger S, et al. Specific collagen peptides increase adaptions of patellar tendon morphology following 14-weeks of high-load resistance training: A randomized-controlled trial. Eur J Sport Sci. 2023;23(12):2329-2339. pubmed.ncbi.nlm.nih.gov/37424319/
- Devries MC, Phillips SM. Creatine supplementation during resistance training in older adults: a meta-analysis. Med Sci Sports Exerc. 2014;46(6):1194-1203. pubmed.ncbi.nlm.nih.gov/24576864/
- Johnston AP, et al. Effect of creatine supplementation during cast-induced immobilization on the preservation of muscle mass, strength, and endurance. J Strength Cond Res. 2009;23(1):116-120. pubmed.ncbi.nlm.nih.gov/19130643/
- Ang-Lee MK, Moss J, Yuan CS. Herbal medicines and perioperative care. JAMA. 2001;286(2):208-216. pubmed.ncbi.nlm.nih.gov/11448284/
- Smith MD, et al. Preoperative carbohydrate treatment for enhancing recovery after elective surgery. Cochrane Database Syst Rev. 2014;(8):CD009161. pubmed.ncbi.nlm.nih.gov/25121931/
- Roy BD, et al. Creatine monohydrate supplementation does not improve functional recovery after total knee arthroplasty. Arch Phys Med Rehabil. 2005;86(7):1293-1298. pubmed.ncbi.nlm.nih.gov/16003653/
