Macro Tracking with Chronic Kidney Disease: When 'Eat More Protein' Is the Wrong Advice

TL;DR

• Almost every article on this blog tells you to eat more protein. CKD is the exception, and it is a big one: non-dialysis stages 3-5 are usually managed on 0.6-0.8 g/kg/day, not the 1.6-2.2 g/kg most trackers aim for.
• Dialysis flips it back. Haemodialysis strips amino acids out of your blood every session, so needs rise to roughly 1.0-1.2 g/kg/day.
• Potassium, phosphate and sodium matter more than your macro split, and only one of the three is reliably printed on a UK food label.
• Phosphate additives are absorbed at around 90%, against 40-60% for phosphorus bound in plants. Reading ingredients beats reading the nutrition panel.
• Your numbers come from your renal dietitian and your bloods. A tracker’s job is to show you whether you hit them, not to invent them.

Why the usual advice reverses

Protein metabolism produces urea, creatinine and acid load, and healthy kidneys clear all of it without complaint. That is why high-protein advice is safe for the general population, and why the sceptical line about protein “damaging your kidneys” is unfounded in people with normal renal function.

Reduced filtration changes the maths. When eGFR falls, that nitrogen load builds up, and a large body of evidence suggests lowering protein intake slows progression toward dialysis and reduces uraemic symptoms such as nausea, itching and appetite loss.

Typical guidance for adults with CKD stages 3-5 who are not on dialysis sits around 0.55-0.8 g/kg of body weight per day, with the lower end used in non-diabetic CKD under close supervision and the 0.6-0.8 band more common where diabetes is also present, which overlaps with the targets in our type 2 diabetes macro guide more than you would expect. For an 80 kg adult that is roughly 48-64 g of protein a day, which is less than many people eat at a single evening meal.

Two things follow that people get wrong.

This is prescribed, not chosen. The safe version of a low-protein diet involves regular bloods, weight monitoring and a renal dietitian checking you are not sliding into malnutrition. The unsupervised version is how people arrive at their nephrology appointment underweight with muscle wasting, which carries its own bad outcomes. Do not set your own restriction off a blog post, including this one.

Calories must stay up. Cut protein without replacing the energy and your body breaks down its own muscle for fuel, which produces exactly the nitrogen load you were trying to avoid. Energy targets in the region of 25-35 kcal/kg/day are standard. In practice this means carbohydrate and fat do the heavy lifting, which feels wrong to anyone who has spent years in flexible dieting.

Dialysis reverses it again

Once you start haemodialysis, each session removes amino acids along with the waste products. Protein requirements go up, commonly to 1.0-1.2 g/kg/day, and low intake becomes the bigger threat. Peritoneal dialysis carries its own protein losses through the dialysate.

If you have been eating a restricted-protein diet for two years and then start dialysis, the habits that were protecting you become the thing making you frail. The transition is a genuine re-set of your targets, and it is worth asking your team for new numbers on the day the plan changes rather than a month later.

The three minerals that outrank your macro split

Potassium

High potassium is the one that can put you in hospital quickly, because it affects heart rhythm. Not everyone with CKD needs to restrict it; it usually becomes a concern in later stages or with certain medications, and your bloods decide.

The awkward part for a tracker: potassium is not required on UK nutrition labels, so most food databases carry it patchily. Chowdown pulls from USDA data, which does include potassium for a large share of whole foods, but treat any figure for a branded ready meal with suspicion.

Practical anchors matter more than logged numbers here. Potatoes, tomatoes, bananas, oranges, avocado, dried fruit, nuts, chocolate and coffee run high. Apples, berries, grapes, cabbage, green beans and white rice run lower. Boiling potatoes and root veg in plenty of water, then draining, leaches a meaningful share of the potassium out; roasting and steaming do not.

Watch salt substitutes. The “reduced sodium” salts sold in every UK supermarket replace sodium chloride with potassium chloride, which is genuinely good advice for the general population and genuinely dangerous in advanced CKD.

Phosphate

Phosphate is where reading ingredients beats reading macros. Phosphorus bound naturally in plants is absorbed at roughly 40-60%, in animal foods somewhat higher, and inorganic phosphate additives at around 90%. The additive form is the problem, and it is invisible in the nutrition panel.

Scan ingredient lists for anything with “phos” in it: sodium phosphate, potassium phosphate, phosphoric acid, calcium phosphate. It turns up in processed cheese, cola, cured and injected meats, instant puddings, some breads and a lot of ready meals. Cutting additive phosphate lowers your phosphate load without cutting the protein you can barely afford to lose.

If you have been prescribed phosphate binders, they only work when taken with the meal, not an hour later.

Sodium

Sodium restriction is close to universal in CKD, for blood pressure, fluid retention and proteinuria. Common targets sit at or below 2 g of sodium a day, which is about 5 g of salt. If you want the fuller picture on why sodium deserves more attention than it gets, our sodium and electrolytes guide covers the general case; CKD just raises the stakes.

This is the one your tracker handles well, because sodium is on every UK label. It is also the one where the numbers surprise people: bread, bacon, cheese and shop-bought soup will use your entire day before you have touched the salt cellar.

What tracking is actually for here

You are not optimising a physique. You are producing evidence for a clinical conversation, the same principle that runs through our guide on macro tracking with gout, another condition where the food rules are set by bloods, not by aesthetics.

Log a normal fortnight before you change anything. Your renal dietitian’s first question is what you currently eat, and “about 60 grams of protein, I think” is worth far less than an actual two-week average.

Track protein as the constrained resource. Once your ceiling is 60 g, the question becomes which 60 g. Eggs, fish, dairy and meat give you complete protein per gram; there is no case for spending 15 g of your allowance on protein that arrives incidentally with a large phosphate and potassium load. This is where a food-first, additive-light diet does most of the work.

Weigh yourself weekly and treat unintended loss as a red flag, not a win. On a restricted diet, falling weight usually means insufficient energy, and the fix is more carbohydrate and fat, not more discipline.

Take the export to appointments. A month of logged intake alongside your bloods lets your team see whether a rising phosphate is a diet problem or a binder-timing problem. That is a different conversation from trying to remember what you ate.

The honest limits

CKD nutrition is individual to a degree that no app can resolve. Stage, cause, diabetes status, blood pressure, medications, fluid status and your latest bloods all move the targets, and they move them in different directions. Anyone giving you a fixed macro split for CKD without seeing your numbers is guessing.

What a tracker can do is narrow and real: show you your protein average against a target somebody qualified set, flag the sodium you did not know was there, and give you a record instead of a recollection.

Chowdown is free, tracks sodium and potassium alongside the macros, and lets you save the meals you have already cleared with your dietitian. Bring the data to the appointment; let the renal team set the numbers.