Three days after my uncle Ray came home from his kidney operation, my aunt rang me in a state. Someone at church had told her that people with one kidney could not eat protein, someone else had said no bananas because of potassium, and a leaflet from the ward said to drink plenty but she had also read that too much water was dangerous. Ray, meanwhile, was sitting in his armchair eating dry crackers because he was frightened of everything else. That evening I sat with them and a notepad and we worked out a kidney cancer diet that a real person could actually follow, and then I went and checked it against the guidelines.
What we found surprised all three of us. For most people after kidney cancer surgery, the right diet is not a restrictive renal diet at all. It is a heart healthy, mostly plant based, moderately salted way of eating that protects the remaining kidney, helps with weight, lowers blood pressure and, as far as the evidence can tell, lowers the chance of the cancer returning. The exercise advice is similarly liberating: move, and move more than you think you should. Here is that plan, with the studies behind it, covering what to eat during treatment, foods to eat and avoid after kidney removal, and a weekly exercise routine.
First: do you actually need a "renal diet"?
This is the question that determines everything else, so ask your team for one number: your estimated glomerular filtration rate, or eGFR, from your post surgery blood test. It measures how well your remaining kidney tissue filters.
- eGFR 60 or above: your kidney function is in the normal range. You do not need to restrict potassium, phosphorus or fluid. Your diet goals are protecting that function long term, managing weight and blood pressure, and general cancer risk reduction. Most people after a partial nephrectomy, and many after losing a whole kidney, are in this group.
- eGFR 45 to 59: mild to moderate reduction. Modest protein, careful salt, and a review with a renal dietitian. Potassium and phosphorus usually still do not need restricting unless blood tests say so.
- eGFR under 45, or rising potassium or phosphate on blood tests: you need individual advice from a renal dietitian. The general guidance below still applies but specific limits may be added.
Ray's eGFR after his partial nephrectomy was 71. The banana ban was unnecessary. So was the fear of protein. What he did need was to lose weight, get his blood pressure down and cut his salt in half, and those three things are the core of the plan.
The two numbers that matter most after kidney removal
Protein: enough, not extra
When one kidney is removed, the other enlarges and works harder, a process called hyperfiltration. Very high protein intakes push that harder still. The 2024 KDIGO guideline for people with reduced kidney function recommends 0.8 grams of protein per kilogram of body weight per day, and specifically advises against intakes above 1.3 g/kg (KDIGO 2024 Clinical Practice Guideline for CKD). For a 75 kg person that is around 60 grams a day, which is a normal, adequate amount: an egg at breakfast, a portion of beans or fish at lunch, a palm sized piece of chicken or tofu at dinner. What it rules out is protein shakes, double meat portions and high protein fad diets. During the first few weeks of healing after surgery, slightly more is reasonable; ask your team.
Salt: under 5 to 6 grams a day
Salt raises blood pressure, and blood pressure is both a cause of kidney cancer and the main driver of long term damage to the remaining kidney. KDIGO recommends under 2 grams of sodium, roughly 5 grams of salt, a day. Around three quarters of the salt most people eat comes from bread, processed meat, cheese, sauces, ready meals and takeaways rather than the salt cellar, so the practical change is cooking more from scratch and reading labels. Salt substitutes based on potassium chloride are fine if your eGFR is over 60 but should be avoided if it is lower.
Foods to eat after kidney removal, and why
Vegetables, especially the cruciferous family
A pooled analysis of 13 prospective studies found people eating the most fruit and vegetables had about 30 percent lower kidney cancer risk than those eating the least (Lee et al., Cancer Epidemiology, Biomarkers and Prevention, 2009), and a meta-analysis focusing on cruciferous vegetables found a 19 percent reduction (Liu et al., Nutrition and Cancer, 2013). Broccoli, cauliflower, cabbage, kale, Brussels sprouts and rocket most days. They are also naturally low in salt and rich in potassium and fibre, both of which help blood pressure.
Fruit
Two to three portions a day. Berries, apples, citrus and pears. Unless your eGFR is under 45 or your potassium is high, bananas, oranges and dried fruit are fine. Whole fruit rather than juice, which delivers the sugar without the fibre.
Whole grains and legumes
Oats, brown rice, wholegrain bread, quinoa, lentils, chickpeas and beans. They provide plant protein, which appears gentler on the kidney than the same amount from animal sources, plus fibre that improves blood pressure, weight and gut health. Legumes are a useful way to meet protein needs without pushing intake high.
Fish, poultry, eggs and dairy in moderate portions
Oily fish twice a week for omega 3 fats, which lower triglycerides and inflammation. Chicken, turkey, eggs and yoghurt in palm sized portions. Cheese is a major salt source, so treat it as a garnish.
Olive oil, nuts and seeds
The Mediterranean pattern built on these has the strongest evidence of any dietary pattern for protecting kidney function, lowering blood pressure and reducing cancer mortality. Two tablespoons of olive oil and a small handful of unsalted nuts a day is a good target.
Water
For people with normal kidney function, 1.5 to 2 litres of fluid a day is a reasonable aim, more in heat or with exercise. There is no need to force large volumes, and no evidence that "flushing" the kidney helps. If your eGFR is low or you have been told to limit fluid, follow that advice instead. Coffee and tea count and are associated with slightly lower kidney cancer risk in cohort studies.
Foods to avoid after kidney removal
- Processed meat (bacon, ham, sausages, salami) and charred or well done red meat. Both are linked with higher kidney cancer risk, the former through nitrates and salt, the latter through heterocyclic amines formed at high heat (Daniel et al., American Journal of Clinical Nutrition, 2012). Red meat once or twice a week, cooked gently, is a sensible ceiling.
- Sugary drinks and sweets. The World Cancer Research Fund's continuous update rates the evidence that excess body fat causes kidney cancer as convincing, and sugary drinks are the most reliable route to it (WCRF/AICR Third Expert Report, Kidney Cancer). Diet drinks have not been shown to cause kidney cancer, despite what circulates online, though water is better for everyone.
- High salt foods: ready meals, takeaways, crisps, stock cubes, soy sauce, salted nuts, most cheeses and processed bread.
- Excess alcohol. Up to one drink a day is not associated with higher kidney cancer risk, but three or more raises blood pressure and harms the remaining kidney. Fourteen units a week is the upper limit; less is better.
- Anti inflammatory painkillers such as ibuprofen and naproxen taken regularly. Not a food, but the most common way people accidentally damage a single kidney. Paracetamol is the safer choice for everyday pain; check with your team about anything regular.
- Herbal "kidney cleanse" or "cancer fighting" supplements. Several, including high dose vitamin C, aristolochia, creatine and some Chinese herbal mixtures, can harm the kidney or interfere with immunotherapy. Tell your oncologist about every supplement you take.
Eating during treatment
The weeks after surgery
Appetite is often poor for two or three weeks, and the bowel is sluggish after anaesthetic and painkillers. Small frequent meals, soft foods, soups with beans or lentils for protein, yoghurt, eggs and fruit. Keep fluids up. Constipation is almost universal: fibre, fluid, walking and a gentle laxative if needed. Do not worry about weight in this window; the priority is healing.
During immunotherapy or targeted therapy
Drugs such as pembrolizumab, nivolumab, axitinib and lenvatinib bring their own dietary issues. Diarrhoea is common and, with immunotherapy, must be reported promptly because it can signal colitis. Taste changes, mouth soreness and loss of appetite are frequent with the targeted drugs; bland, soft, cool foods, small portions and protein at every meal help. Some targeted drugs raise blood pressure, which makes the salt advice above more important, not less. Grapefruit and Seville oranges interact with several of these drugs and should be avoided; ask your pharmacist about your specific medicine.
A sample day
| Meal | What to eat | Protein |
|---|---|---|
| Breakfast | Porridge with semi skimmed milk, blueberries, a few walnuts; coffee or tea | 12 g |
| Mid morning | An apple or pear, a glass of water | 0 g |
| Lunch | Lentil and roasted vegetable soup, a slice of wholegrain bread, side salad with olive oil | 16 g |
| Afternoon | Natural yoghurt with a sliced kiwi | 6 g |
| Dinner | Baked salmon (or chicken or tofu), brown rice, steamed broccoli and roasted peppers with lemon and herbs, no added salt | 26 g |
| Evening | Herbal tea, a square of dark chocolate | 1 g |
Total: about 60 grams of protein, around 4 grams of salt, 35 grams of fibre, seven portions of vegetables and fruit. It is not a diet anyone has to suffer through, which is the point. Ray has eaten a version of it for six years.
Exercise with kidney cancer: what the evidence says
In 2019 the American College of Sports Medicine convened an international roundtable to review every trial of exercise in people with cancer. Its conclusion was unambiguous: structured exercise during and after treatment reduces fatigue, anxiety and depression, and improves physical function and quality of life, with strong evidence across cancer types, and it is safe when tailored appropriately (Campbell et al., Medicine and Science in Sports and Exercise, 2019). For kidney cancer specifically, physical activity is also linked to lower incidence in the first place, and to better outcomes on immunotherapy in early studies. The recommended dose is 150 minutes of moderate aerobic activity a week plus two sessions of resistance training, built up gradually.
After surgery: a week by week guide
| When | What is usually safe | What to avoid |
|---|---|---|
| Days 1 to 7 | Walking from day one: corridors in hospital, then five to ten minutes at home several times a day. Deep breathing exercises. | Lifting anything heavier than a kettle. Driving until you can brake hard without pain. |
| Weeks 2 to 4 | Walks building to 20 to 30 minutes. Gentle stretching. Light household tasks. Stationary bike at low resistance from week 3 if comfortable. | Lifting over 5 kg, core exercises, anything that strains the abdomen. |
| Weeks 4 to 6 | Brisk walking 30 minutes most days. Swimming once wounds are fully healed. Light resistance bands. | Heavy lifting, contact sports, high intensity intervals. |
| After 6 weeks (8 to 12 after open surgery) | Full return to normal activity with your surgeon's agreement, including gym, running and lifting, built up gradually. | Nothing specific once cleared, apart from protecting your remaining kidney from direct blows. |
A weekly routine once you are recovered
- Five days: 30 minutes of brisk walking, cycling or swimming, at a pace where talking is possible but slightly effortful. Ten minutes after each meal works well and helps blood sugar and blood pressure.
- Two days: 20 to 30 minutes of resistance work: squats, step ups, rows, presses, using bands, dumbbells or body weight. Muscle protects against the weight regain and insulin resistance that drive both recurrence risk and kidney damage.
- Daily: break up sitting every 30 to 45 minutes. Sedentary time is independently linked to kidney cancer risk.
- Weekly: one longer, enjoyable activity: a hike, a long bike ride, dancing, gardening. Adherence over years is what matters, and enjoyment predicts adherence better than anything.
Exercising during drug treatment
Fatigue on immunotherapy and targeted drugs is real, and the counterintuitive evidence is that gentle daily activity reduces it more than rest does. On bad days, a ten minute walk is a success. On days with fever, dizziness, significant diarrhoea or chest symptoms, rest and call your team. If your platelets or blood counts are low, avoid contact sports and heavy lifting until they recover. People with bone metastases should get individual advice about which movements are safe.
Protecting a single kidney during sport
The American Academy of Pediatrics reviewed the evidence on contact sports with one kidney and concluded that kidney injury in sport is rare and that most people can participate, with the decision made individually. Rugby, martial arts and similar sports carry a small risk of a direct blow; a discussion with your surgeon and possibly a protective guard is sensible. Running, cycling, swimming, tennis, football and the gym carry no special risk.
Weight after kidney cancer: an honest note
You may read about an "obesity paradox" in kidney cancer, where heavier patients seem to do better after diagnosis. This is largely a statistical artefact: people who are losing weight at diagnosis are often sicker, and BMI is a poor measure of body composition. The consistent finding is that muscle mass predicts better outcomes and that gaining fat after treatment does not. Losing weight slowly, at 0.5 to 1 kg a week, while keeping protein adequate and doing resistance exercise to preserve muscle, remains the right goal for most people who are overweight. Our BMI calculator is a fair starting point, and it shows the lower thresholds that apply to South Asian, Chinese and Black groups. Do not attempt weight loss during active treatment without discussing it with your team.
What changed for Ray and my aunt
The crackers went in the bin that evening. Within a month Ray was eating porridge and walking to the paper shop, and within a year he had lost twenty kilograms without ever feeling he was on a diet, because he was not. His blood pressure medication was halved. His eGFR is unchanged at six years. My aunt, who cooked all of it, lost a stone herself and says her knees have never been better. The diagnosis was the worst day of their year. The way they ate and moved afterwards turned out to be one of the best things that happened to their marriage, which is not something either of them would have believed in that armchair with the crackers.
If you are earlier in the process and still trying to understand what you are dealing with, start with Is kidney cancer curable? Survival rates by stage and treatment, and for what raises risk in the first place, kidney cancer symptoms, causes and prevention.
Read next
- Kidney cancer symptoms, causes and how to lower your risk
- Is kidney cancer curable? Survival rates by stage and what treatment involves
- BMI calculator with Asian and Black thresholds
- Kidney stone diet and exercise: what to eat and how to move
Frequently asked questions
What foods should you avoid after kidney removal?
High salt foods, processed meat, sugary drinks, excess alcohol and very high protein intakes. Regular anti inflammatory painkillers such as ibuprofen should also be avoided. Potassium and phosphorus do not need restricting unless your kidney function is significantly reduced.
Can you eat bananas with one kidney?
Yes, if your eGFR is 60 or above, which it is for most people after kidney cancer surgery. Potassium restriction only applies when kidney function is substantially reduced or blood potassium is high.
How much protein should I eat with one kidney?
About 0.8 grams per kilogram of body weight per day, roughly 55 to 70 grams for most adults, and not more than 1.3 g/kg. That is a normal intake, not a low one. Avoid protein supplements and high protein diets unless your team advises otherwise.
Is exercise safe during kidney cancer treatment?
Yes, and it is recommended. Moderate exercise during and after treatment reduces fatigue, improves mood and physical function, and is safe when built up gradually. Walking from the first day after surgery is encouraged; heavy lifting waits six weeks.
This article is for general information and does not replace advice from your oncology team or a renal dietitian, particularly if your kidney function is reduced or you are on active treatment.
