A home-cooked diet is only as good as its 5 weakest numbers, and the two that fail first are calcium and taurine. Meat alone runs a calcium to phosphorus ratio near 0.3, against a target of 1.1 to 1.3, and boiling leaches taurine that the recipe never puts back. A 4.5 kg cat eating 218 g of a balanced 120 kcal per 100 g mix gets 260 kcal, 0.39 g of calcium, and 0.33 g of phosphorus; the same bowl without a calcium source delivers about a fifth of the calcium and no taurine at all.
Long-term home cooking needs a recipe written by a veterinary nutritionist, with the calcium to phosphorus ratio held at 1.1 to 1.3 and taurine added, not assumed.
Check 1: calcium to phosphorus, 1.1 to 1.3
This is the ratio that decides whether bone holds its mineral. Muscle meat is rich in phosphorus and poor in calcium: 100 g of raw chicken breast carries roughly 5 to 15 mg of calcium against 200 to 230 mg of phosphorus, a ratio near 0.05. Feed that for 6 to 12 months and the body pulls calcium out of bone, which is nutritional secondary hyperparathyroidism, seen as jaw thickening, loose teeth, and a stilted walk.
Fix it with a weighed calcium source, carbonate or ground eggshell, at the amount the recipe specifies, not by adding bone. Bone brings its own phosphorus and pushes the ratio back down. Weigh to 0.1 g on a kitchen scale; a teaspoon of powder is not a unit.
Check 2: taurine, always added
Cats cannot make enough taurine and lose it in cooking water. Deficiency shows up as dilated cardiomyopathy (DCM), a thinner heart muscle that cannot pump, and as retinal degeneration that starts as night blindness. Both are permanent once they appear. Taurine is also destroyed by thawing and reheating, so it goes in after the food cools, in the amount on the premix label or in the nutritionist's recipe.
A recipe built on chicken thigh and rice with no supplement is the classic failure: protein looks fine, the amino acid is missing. If a cat on a home diet starts breathing fast at rest or stops jumping, that is a vet visit this week, with an ultrasound of the heart.
Check 3: protein on a dry matter basis
Never compare protein percentages as fed, because water dilutes them. Convert: dry matter (DM) percent = 100 − moisture. Protein DM = protein as fed ÷ DM × 100. A stew at 12 percent protein and 72 percent moisture is 12 ÷ 28 × 100 = 43 percent protein DM, which is a good adult level. The same 12 percent in a mix that is only 60 percent water is 30 percent DM, which is thin for a cat.
Check 4: fat and energy density
Energy is where home cooking goes wrong quietly. Use the modified Atwater values: 3.5 kcal per gram of protein, 8.5 per gram of fat, 3.5 per gram of carbohydrate. A 100 g batch with 12 g protein, 5 g fat, 10 g carbohydrate, and 1 g ash gives 3.5 × 12 + 8.5 × 5 + 3.5 × 10 = 42 + 42.5 + 35 = 119.5 kcal, call it 120 kcal per 100 g. A fattier batch at 8 g fat is 9.5 kcal more per 100 g, which over 218 g a day is 21 extra kcal, or 1 kg of fat over a year.
| Number | Target, dry matter basis | Typical plain meat mix | Gap to close |
|---|---|---|---|
| Calcium | 0.6 to 1.0% | 0.10 to 0.20% | 3 to 6 times short |
| Phosphorus | 0.5 to 0.8% | 1.2 to 1.6% | 2 times over |
| Calcium to phosphorus | 1.1 to 1.3 | 0.05 to 0.30 | 4 to 20 fold low |
| Crude protein | 26% minimum | 35 to 50% | usually met |
| Taurine | added per recipe | 0 mg added | fully missing |
| Energy | matched to RER | 119 kcal per 100 g | weigh the batch |
Check 5: the trace list
Zinc, iron, copper, iodine, vitamin A, D, E, and the B group all sit below the level a meat and rice mix provides. Liver covers vitamin A and copper but overshoots: 10 g of liver per 100 g of food is already generous, and daily liver at 30 g pushes vitamin A into the toxic range over months, with bone pain and a stiff neck. Vitamin E and zinc are the two that go short in fish-heavy recipes, and iodine goes short in any recipe with no fish or iodized source.
This is the part owners cannot balance by eye. A premix sold for home-cooked cat diets, used at its label rate, covers the trace list and the taurine in one step; a nutritionist's recipe covers it with named grams.
One worked day, 218 g
Take the 120 kcal per 100 g batch: 12 percent protein, 5 percent fat, 10 percent carbohydrate, 72 percent moisture, and a measured 0.18 percent calcium and 0.15 percent phosphorus. A 4.5 kg neutered cat needs 260 kcal, so 260 ÷ 119.5 × 100 = 218 g a day, split into 3 meals of 73 g.
Check the numbers on that 218 g. Dry matter: 218 × 0.28 = 61 g. Protein: 218 × 0.12 = 26.2 g, which is 26.2 ÷ 61 = 43 percent DM. Calcium: 218 × 0.0018 = 0.39 g. Phosphorus: 218 × 0.0015 = 0.33 g. Ratio: 0.39 ÷ 0.33 = 1.20, inside 1.1 to 1.3. Calcium as DM: 0.39 ÷ 61 × 100 = 0.64 percent, inside 0.6 to 1.0 percent.
Cost scales with the meat: at 8 dollars per kg of chicken breast, the 150 g in that day costs 1.20 dollars, and the whole day lands near 1.50 dollars against 2 to 3 dollars for 2 cans of pâté. The cost tool holds the yearly figure once you enter the meat price and grams per day.
Making a batch that repeats
Cook one batch of 1,500 g, cool it, portion 218 g into 7 containers, and freeze at −18 C for up to 90 days. Thaw in the fridge over 12 hours, never on the counter, and warm to room temperature only, because heat above 60 C destroys more taurine. Add the supplement after cooling, per container, and write the date on the lid.
Recipes that already pass the 5 checks are in home-cooked diet recipes, and the arithmetic behind substitutions is in recipe balance. Substituting chicken for beef is fine; substituting rice for meat is not, and it drops protein DM by 10 points or more.
What must send you to a vet
Book a visit for lameness or a stiff gait, a new heart murmur, breathing over 40 breaths a minute at rest, night blindness, dropping 10 percent of body weight in 6 months, or refusing food for 3 days. Ask for a chemistry panel with calcium and phosphorus, and for a recipe review if the diet has run over 3 months without one. A home-cooked diet is a prescription-strength project: safe when the 5 numbers are held, harmful when one of them drifts for a year.
Five steps before the next batch
- Get a written recipe from a veterinary nutritionist before cooking anything long term.
- Weigh calcium and taurine to 0.1 g per batch, and add taurine after the food cools.
- Compute protein and calcium on a dry matter basis, not from the as-fed percentages.
- Portion 218 g per day for a 4.5 kg cat and freeze in 7 day units at −18 C.
- Weigh the cat every 2 weeks and recheck bloodwork every 6 to 12 months.
Terms mentioned in this article
Frequently asked
Can I just add a calcium supplement and keep the recipe?
Only if the amount is calculated for that exact recipe. Calcium needs to hold a 1.1 to 1.3 ratio against the phosphorus in the mix, and phosphorus moves when you change the meat, so a fixed spoon of powder is a guess. Have a nutritionist run the recipe once, then repeat it with a scale to 0.1 g.
Is raw better than cooked for taurine?
Raw keeps more taurine, but cooking water takes a share and freezing and reheating take more, so either way the diet needs added taurine at the label or recipe rate. Raw brings its own bacterial risk for the cat and the household, which is why many owners cook and supplement instead.
How do I know the diet is working?
Three signals over 3 months: steady weight within 2 percent, a body condition score that holds at 5, and a normal coat with no flaking. Bloodwork with calcium, phosphorus, and a kidney panel at 6 months catches the quiet failures, and a heart ultrasound checks taurine status if breathing or activity changed.
Related guides
- Homemade Cat Food: Balance Calcium, Taurine, E
- Cat Grass: 7-Day Wheatgrass and 10 cm Grazing
- How to Switch Cat Food: The 7-Day Schedule, With Grams
- Switching an 11-Year-Old Cat's Food: 7-Day Gram Plan
- Taurine in Cat Food: 250-500 mg, and Who Falls Short
- Carbs in Cat Food: Dry Matter, NFE, and the 10% Line