Short answer: For most people, the most useful supplement after heart surgery is simply enough protein, often from a shake. Appetite is usually poor for 2 to 4 weeks after bypass surgery,[1] right when your body needs more protein, not less. Surgical nutrition guidelines estimate about 1.5 g of protein per kg of ideal body weight a day.[2] Omega-3s look safe around heart surgery, but their benefits are modest.

Your surgical team's instructions come first. If you have kidney disease, diabetes, a sodium or fluid limit, or take warfarin or another blood thinner, ask your team before adding any shake or supplement.

This guide covers how much protein to aim for (with the math), what the research says about carb loading, amino acids and omega-3s in heart surgery, how to eat when you have no appetite, and a week-by-week timeline of what to expect.

Understanding Cardiac Surgery Recovery

Cardiac surgery, whether coronary artery bypass grafting (CABG), valve repair, or combined procedures, is often lifesaving. But recovery can feel longer and more intimidating than patients expect.

The first few weeks commonly include:

  • Significant fatigue
  • Fluctuating pain
  • Poor appetite
  • Sleep disruption
  • Anxiety about activity
  • Fear of damaging the sternum

That experience is normal. Heart surgery sets off a strong inflammatory and metabolic stress response. The body enters a catabolic state, meaning muscle breakdown increases while appetite often falls.

Recovery is not just about the heart. It's about rebuilding tissue, preserving muscle, and stabilizing metabolism.

Muscle matters more than most people realize. A 2023 review of 12 studies and 2,717 heart surgery patients found that people with low muscle mass and strength (sarcopenia) had about 2.4 times the odds of dying early after surgery, along with longer ICU stays and longer time on a breathing tube.[3] You cannot rebuild muscle in the week before surgery. You can try to limit how much you lose afterward.

Three nutrition strategies supported by clinical research deserve attention:

  1. Preoperative carbohydrate loading
  2. Adequate perioperative protein intake
  3. Strategic omega-3 supplementation

How Much Protein Do You Need After Heart Surgery?

The European Society for Clinical Nutrition and Metabolism (ESPEN) estimates that surgical patients need about 1.5 g of protein per kg of ideal body weight per day.[2] Ideal body weight is not always your scale weight, so ask your team or a dietitian which number to use. Here is what that looks like:

Ideal body weight Daily protein at 1.5 g/kg Per eating time, split 4 ways
60 kg (132 lb) 60 x 1.5 = 90 g 90 / 4 = about 23 g
70 kg (154 lb) 70 x 1.5 = 105 g 105 / 4 = about 26 g
80 kg (176 lb) 80 x 1.5 = 120 g 120 / 4 = 30 g
90 kg (198 lb) 90 x 1.5 = 135 g 135 / 4 = about 34 g

One OptiFuel packet has 25 g of protein. At 80 kg, that covers 25 of your 120 g, or about a fifth (25 / 120 = 21%). The rest still has to come from food: eggs, Greek yogurt, fish, chicken, beans, tofu and milk.

If you are over 65, an international expert group (PROT-AGE) recommends 1.2 to 1.5 g/kg a day for older adults with acute or chronic illness. At 75 kg that is 75 x 1.2 = 90 g to 75 x 1.5 = 112.5 g. The same group notes that people with severe kidney disease who are not on dialysis may need to limit protein instead.[4] If you have any kidney problems, check your target with your doctor before you push protein higher.

Spread it out. In a small lab study of healthy adults, eating about 30 g of protein at each of 3 meals switched on muscle building about 25% more over a day than eating most of the same protein at dinner.[5] It was not done in heart patients, but it supports a simple habit: some protein every time you eat.

What the Research Says: Carbs, Protein and Omega-3s

1) Carb Loading Before Cardiac Surgery

The old rule was nothing after midnight. US anesthesia guidelines now allow healthy adults having elective procedures to drink carbohydrate-containing clear liquids up to 2 hours before anesthesia.[6] Heart surgery teams set their own rules, so ask yours what applies to you.

Why it matters:

  • Surgery temporarily makes the body less responsive to insulin.
  • In a small double-blind study of hip replacement patients, insulin sensitivity fell 18% after a carbohydrate drink compared with 43% after a placebo drink.[7]
  • In a randomized trial of 252 adults, those who had a carbohydrate drink the evening before and the morning of surgery felt less hungry and less anxious while they waited than those who fasted.[8]

A Cochrane review of 27 trials (1,976 adults, including 4 heart surgery trials) linked carbohydrate drinks with a hospital stay about 0.3 days shorter than placebo or fasting. The evidence quality was very low, there was no clear difference against a placebo drink alone, and complication rates did not change.[9] A larger analysis of 43 trials found the small benefit came mainly from not fasting, not from the carbohydrate itself.[10] So think of carb loading as a comfort and metabolism step, not a shortcut out of the hospital.

Carb loading is not a heavy meal. It is a clear carbohydrate drink, which is why anesthesia guidelines treat it like other clear liquids. If you have diabetes, ask first: ESPEN advises against carbohydrate drinks in severe diabetes, especially with slow stomach emptying.[2] Our guide to the carb loading drink before surgery covers timing and how to choose one.

2) Protein and Amino Acids: Evidence in Cardiac Surgery

Cardiac surgery places heavy demand on:

  • Wound healing
  • Immune response
  • Collagen synthesis
  • Preservation of skeletal muscle

And many patients enter surgery already nutritionally borderline.

Trial: amino acid supplement for 30 days before heart surgery

In a double-blind, placebo-controlled trial of adults having heart surgery (60 completed it), patients took a daily mix of 7 g L-arginine, 7 g L-glutamine and 1.5 g HMB (a leucine breakdown product) for 30 days before their operation.[11] Compared with placebo, the supplement group had:

  • A shorter hospital stay (median 5 vs 6 days)
  • A shorter ICU stay (median 2.5 vs 3.5 days)
  • Lower troponin and CK-MB, blood markers of heart muscle injury
  • Lower inflammation markers, including IL-6 and CRP, in a companion report from the same trial[12]

The authors say the results need confirming in a larger trial.

Trial: immune-enhancing nutrition (arginine plus omega-3s) before surgery

In a randomized, placebo-controlled trial of 50 high-risk patients scheduled for bypass surgery (age 70 or older, weak heart pumping, or planned mitral valve replacement), a drink with L-arginine, omega-3 fatty acids and yeast RNA taken for at least 5 days before surgery improved immune response markers and lowered IL-6.[13]

This suggests perioperative nutrition can shift inflammatory biology in measurable ways. To be clear about what it does not show: neither trial tested a Thrive product. No Thrive product contains HMB, and arginine is only in the Recovery and Strength Mix, at a different dose. The practical lesson is broader. Protein intake is not optional during cardiac surgery recovery. It is foundational.

3) Omega-3s: What They Do (and Don't Do)

Omega-3 fatty acids have been studied a lot in heart surgery.

Postoperative atrial fibrillation? The large OPERA trial (1,516 patients in 28 centers) found that fish oil before and after surgery did not reduce postoperative atrial fibrillation: 30.0% with fish oil vs 30.7% with placebo.[14] So omega-3s should not be viewed as a rhythm protector.

Bleeding? A later analysis of the same trial found fish oil did not increase major bleeding, and patients needed fewer units of transfused blood.[15]

Hospital stay? A 2024 meta-analysis of bypass patients pooled 7 trials and found omega-3s were linked with a hospital stay about 0.58 days shorter. The authors urge caution because the trials differed a lot from each other.[16]

The effects are modest. OPERA used far more fish oil (8 to 10 g over the days before surgery, then 2 g a day) than the small amount in OptiFuel. Thrive's guidance is that there is no need to stop OptiFuel's fish oil or turmeric before surgery, because the amounts are low. Still, check with your surgeon, especially if you take a blood thinner.

How Long Is Cardiac Recovery?

Cleveland Clinic gives this typical path after open heart surgery:[17]

  • 1 to 2 days in the ICU, then a regular room
  • About 5 days in the hospital on average
  • About 80% recovered by 6 weeks
  • About 95% recovered after 12 weeks

That timeline can feel overwhelming. Nutrition doesn't eliminate it, but it can influence how smoothly you move through it.

Loss of Appetite After Open Heart Surgery: What Helps

A poor appetite is expected. MedlinePlus lists 2 to 4 weeks of poor appetite as normal after bypass surgery, along with constipation from pain medicine and trouble sleeping.[1] In the hospital, your gut is sluggish at first: you start on clear fluids, move to thicker fluids, and most people reach small portions of real food by day 3 or 4. It usually takes about a week for your diet to feel normal again.[17]

What helps on low-appetite days:

  • Eat small and often. Plan on something every few hours instead of 3 big meals.
  • Protein first. Take a few bites of the protein on your plate before the bread or potatoes.
  • Drink it when you can't chew it. A protein shake counts as a mini-meal. OptiFuel is thin enough to sip through a straw. Our quick OptiFuel recipes give you a few ways to change the flavor when everything tastes flat.
  • Plan for constipation. Ask your team about fluids, fiber and a stool softener while you take pain medicine.
  • Weigh yourself daily if your team asks you to. Call your surgeon if you gain more than 2 pounds (1 kg) in a day for 2 days in a row, have a fever over 101°F (38.3°C), or see redness, swelling or more drainage at a wound.[1] Steady weight loss you did not plan is also worth a call, because it can mean you are losing muscle.

Heart-Healthy and High-Protein: Sodium, Fluids and Medicines

Early recovery is about healing. Long term, you also want a heart-healthy pattern. You can do both if you watch a few details.

Sodium. The American Heart Association recommends no more than 2,300 mg of sodium a day, moving toward an ideal limit of 1,500 mg for most adults.[18] Your team may give you a different number. Read the label on any shake. One OptiFuel packet has 65 to 70 mg of sodium depending on flavor. Each OptiCharge carb drink packet has 510 mg, so the 2 packets taken the night before add 1,020 mg. If you are on a strict sodium limit, ask your team before using them.

Fluids. If you have a fluid limit, count your shake. Each OptiFuel packet is mixed with 12 to 16 oz of liquid.

Warfarin and other blood thinners. MedlinePlus advises people on warfarin to keep the amount of certain foods steady from day to day and week to week, and to talk with their provider before starting any vitamins or supplements. Fish oil supplements are on its list of products to be careful with.[19] If you take warfarin, show your clinic the label of any shake or supplement before you start it, and keep taking it consistently once they agree.

Diabetes. Talk to your team before any carbohydrate drink, and keep meals steady so blood sugar stays in the range they set.

For a full food plan by phase, see our cardiac surgery nutrition guide. For eating after any operation, start with what to eat after surgery.

What to Expect: A Week-by-Week Nutrition Timeline

Every recovery is different. This is a typical path, not a promise, and your surgical team's plan overrides it.

When What is usually happening Nutrition focus What the evidence suggests you can expect
About 1 week before Pre-op visits and tests. Anxiety can blunt appetite. Protein at every meal. If you use the Surgical Protocol Kit, start one OptiFuel packet a day. Tell your team about every supplement. You won't feel a change. The goal is to start surgery well fed, because low muscle before heart surgery is linked with worse outcomes.[3]
Night before Fasting rules begin. If your team allows a carb drink: 2 OptiCharge packets at bedtime, each in 12 to 16 oz of water. In trials, a carb drink instead of fasting meant less hunger and anxiety before surgery.[8] It does not shorten your stay on its own.[10]
Hospital, days 1 to 5 1 to 2 days in the ICU, about 5 days in hospital on average.[17] Clear fluids, then thicker fluids, then small portions of food by day 3 or 4. Sips of protein drink when the team allows. Very little appetite. That is normal. The hospital team leads nutrition here.
Home, weeks 1 to 2 Poor appetite, constipation, poor sleep.[1] No lifting, pushing or pulling 10 lb or more.[17] Small meals every few hours, protein first, one OptiFuel packet a day as a drinkable mini-meal, fluids within any limit. Protein alone does not stop muscle loss from inactivity: in older men with a leg in a cast, extra protein did not reduce the loss.[20] Do the walking your team prescribes.
Weeks 3 to 6 Appetite usually returns within 2 to 4 weeks.[1] About 80% recovered by 6 weeks.[17] Move from "eat anything" to heart-healthy meals while keeping 25 to 30 g of protein at each meal. Watch sodium. Eating normal portions again. Use the shake on busy or low-appetite days rather than as a crutch.
Weeks 6 to 12 Cardiac rehab usually starts. Lifting up to 25 lb is often allowed.[17] Protein on rehab days. Ask your cardiologist whether the Recovery and Strength Mix fits, and check kidney function first. This is when muscle can be rebuilt. In healthy adults coming out of a leg cast, creatine plus training brought back thigh muscle and power faster than placebo.[21] It has not been tested in heart patients.
After 12 weeks About 95% recovered.[17] Long-term heart-healthy eating within the AHA sodium limit,[18] with enough protein to hold on to muscle. Back to most normal activity. Keep an eye on weight and strength.

What daily use looks like

Add one OptiFuel packet to a shaker with 12 to 16 oz of water, milk or non-dairy milk, shake, and drink it between meals. Each packet gives you 25 g of protein, 3 g of leucine, vitamin C and vitamin D. On a bad-appetite day it can stand in for a snack you would otherwise skip. If you use the Recovery and Strength Mix too, Thrive suggests OptiFuel between breakfast and lunch and the Mix between lunch and dinner.

Which Thrive Product Fits Where You Are

  • Surgery still ahead: the Surgical Protocol Kit has daily OptiFuel packets, 2 OptiCharge carb drink packets for the night before, and a shaker. Start OptiFuel about 1 week before surgery. If you are insulin dependent, use OptiCharge only after your physician approves it.
  • Surgery already done: the Recovery Protocol Kit is the same OptiFuel, without OptiCharge.
  • Add-on: the Recovery and Strength Mix is the only Thrive product with creatine (5 g) and arginine (2 g). No Thrive product contains zinc. If you have kidney disease or reduced kidney function, check with your doctor before using creatine.

OptiFuel is whey-based and contains milk, is made in the USA and is Informed Sport tested. It is not a meal replacement. Thrive Protocol kits are HSA/FSA eligible, so you can use pre-tax health dollars. For a side-by-side look at protein, omega-3s, vitamin C, vitamin D and creatine, read our guide to the best supplements for surgery 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.

Thrive Protocol Surgical Protocol Kit with OptiFuel and OptiCharge packets

Combine Nutrition With Cardiac Rehab

You may be referred to a formal cardiac rehab program, which offers supervised exercise plus advice on activity and diet.[1] Go if you are offered it.

Nutrition supports tissue rebuilding.
Rehab restores endurance and confidence.

Together they help you break the "fatigue spiral" where low energy means less walking, and less walking means more muscle loss.

Frequently Asked Questions

What are the best supplements after open heart surgery?

Start with protein, because it is the gap most people actually have while appetite is low. Guidelines estimate about 1.5 g per kg of ideal body weight a day around surgery.[2] Omega-3s did not increase bleeding in a large heart surgery trial, but their benefits are modest.[15][16] Anything beyond that should be cleared with your cardiac team, especially if you take a blood thinner or have kidney disease.

Can I drink protein shakes or Ensure after heart surgery?

Usually, yes. ESPEN encourages oral nutrition supplements before surgery for people who cannot meet their energy needs from normal food, and the same logic applies when appetite is low afterward.[2] Check the label for protein grams, sodium and sugar, count the liquid toward any fluid limit, and ask your team first if you have diabetes, kidney disease or take warfarin.

How much protein do I need after bypass surgery?

About 1.5 g per kg of ideal body weight per day is the ESPEN estimate for surgical patients.[2] At 80 kg that is 80 x 1.5 = 120 g, or about 30 g at each of 4 eating times. If you have kidney disease, your doctor may set a lower target.[4]

How long does loss of appetite last after open heart surgery?

MedlinePlus lists 2 to 4 weeks of poor appetite as normal after bypass surgery.[1] Small, frequent meals and drinkable protein help in the meantime. If you are still barely eating after a month, or you are losing weight without trying, tell your team.

Can I take fish oil after heart surgery?

In the 1,516-patient OPERA trial, fish oil before and after heart surgery did not increase major bleeding,[15] but it also did not prevent atrial fibrillation.[14] If you take warfarin or another blood thinner, ask before you start, because fish oil is on the list of products to be careful with.[19]

Can I use my HSA or FSA for a recovery nutrition kit?

Yes. Thrive Protocol kits are HSA/FSA eligible, so you can use pre-tax health dollars.

Bottom Line

Cardiac surgery recovery is long enough to feel frightening, but you have more control over it than it seems.

Evidence shows:

  • Carb loading eases hunger and anxiety before surgery. Any effect on hospital stay is small and mostly comes from not fasting.
  • In small heart surgery trials, an amino acid formula was linked with shorter ICU and hospital stays, and nutrition formulas taken before surgery improved immune and inflammation markers. Larger trials are still needed.
  • Omega-3s did not prevent atrial fibrillation and did not raise bleeding risk. They may modestly shorten hospital stay.
  • Protein, spread through the day and paired with walking and rehab, is the habit that underpins all of it.

If you want to influence recovery rather than simply endure it, nutrition is one of the few controllable levers available.

References

  1. MedlinePlus Medical Encyclopedia. Heart bypass surgery: discharge. US National Library of Medicine. MedlinePlus
  2. Weimann A, et al. ESPEN guideline: clinical nutrition in surgery. Clin Nutr. 2017;36(3):623-650. PubMed 28385477
  3. Ansaripour A, et al. Sarcopenia adversely affects outcomes following cardiac surgery: a systematic review and meta-analysis. J Clin Med. 2023;12(17):5573. PubMed 37685640
  4. Bauer J, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542-559. PubMed 23867520
  5. Mamerow MM, et al. Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults. J Nutr. 2014;144(6):876-880. PubMed 24477298
  6. Joshi GP, et al. 2023 American Society of Anesthesiologists practice guidelines for preoperative fasting: carbohydrate-containing clear liquids with or without protein, chewing gum, and pediatric fasting duration. Anesthesiology. 2023;138(2):132-151. PubMed 36629465
  7. Soop M, et al. Preoperative oral carbohydrate treatment attenuates immediate postoperative insulin resistance. Am J Physiol Endocrinol Metab. 2001;280(4):E576-583. PubMed 11254464
  8. Hausel J, et al. A carbohydrate-rich drink reduces preoperative discomfort in elective surgery patients. Anesth Analg. 2001;93(5):1344-1350. PubMed 11682427
  9. Smith MD, McCall J, Plank L, et al. Preoperative carbohydrate treatment for enhancing recovery after elective surgery. Cochrane Database Syst Rev. 2014;(8):CD009161. PubMed 25121931
  10. Amer MA, et al. Network meta-analysis of the effect of preoperative carbohydrate loading on recovery after elective surgery. Br J Surg. 2017;104(3):187-197. PubMed 28000931
  11. Norouzi M, et al. Evaluation of the recovery after heart surgery following preoperative supplementation with a combination of beta-hydroxy-beta-methylbutyrate, L-arginine, and L-glutamine: a double-blind randomized placebo-controlled clinical trial. Trials. 2022;23(1):649. PubMed 35964137
  12. Norouzi M, et al. The effects of preoperative supplementation with a combination of beta-hydroxy-beta-methylbutyrate, arginine, and glutamine on inflammatory and hematological markers of patients with heart surgery: a randomized controlled trial. BMC Surg. 2022;22(1):51. PubMed 35148750
  13. Tepaske R, et al. Effect of preoperative oral immune-enhancing nutritional supplement on patients at high risk of infection after cardiac surgery: a randomised placebo-controlled trial. Lancet. 2001;358(9283):696-701. PubMed 11551575
  14. Mozaffarian D, et al. Fish oil and postoperative atrial fibrillation: the OPERA randomized trial. JAMA. 2012;308(19):2001-2011. PubMed 23128104
  15. Akintoye E, et al. Fish oil and perioperative bleeding. Circ Cardiovasc Qual Outcomes. 2018;11(11):e004584. PubMed 30571332
  16. Ouagueni A, et al. Omega-3 supplementation in coronary artery bypass graft patients: impact on ICU stay and hospital stay. A systematic review and meta-analysis. Nutrients. 2024;16(19):3298. PubMed 39408265
  17. Cleveland Clinic. What you can expect as you recover from heart surgery. Health Essentials, March 3, 2026. Cleveland Clinic
  18. American Heart Association. How much sodium should I eat per day? heart.org
  19. MedlinePlus Medical Encyclopedia. Taking warfarin. US National Library of Medicine. MedlinePlus
  20. Dirks ML, et al. Skeletal muscle disuse atrophy is not attenuated by dietary protein supplementation in healthy older men. J Nutr. 2014;144(8):1196-1203. PubMed 24919692
  21. Hespel P, et al. Oral creatine supplementation facilitates the rehabilitation of disuse atrophy and alters the expression of muscle myogenic factors in humans. J Physiol. 2001;536(Pt 2):625-633. PubMed 11600695