Switching brands in a recipe: when should you recalculate macros?
You are making a familiar dish with a different brand. If quantities and portions stay the same, you can update just the ingredient that changed. The result is still an estimate, not an exact measurement.
Compare the same basis
Check whether both labels describe the food as sold or prepared. Compare the same quantity, such as 100 g. Figures per pot only match if the pot sizes match. Your Europe explains that European nutrition declarations contain average values, with information per 100 g or 100 ml and sometimes per portion.
Replace one ingredient contribution
Keep your ingredient list and quantities. Multiply each new label value per 100 g by the amount used, then divide by 100. Subtract the old ingredient contribution from the recipe total and add the new one. This assumes nothing else changes: extra milk, sugar or oil used to restore texture must also be counted.
A fictional example
Suppose you use 200 g of product A with 8 g of protein per 100 g: its contribution is about 16 g. Product B has 5 g per 100 g, so the same 200 g contributes about 10 g. The difference is 6 g for the whole recipe, or 1.5 g for each of four equal portions. These invented numbers describe no actual brand and are not a portion recommendation.
Look beyond protein
Repeat the calculation separately for other values you track, respecting the label units. One number cannot describe the whole product. Taste, price, texture and ingredients also matter. Try a small batch if the substitution could alter consistency; a thinner yogurt may require changing the method rather than a direct swap.
Save a clear variation
Record the product, quantity and a photo of the label. Give the recipe version a practical name. Unequal portions should not simply receive the same share of the total: see our article on uneven portions for sufficiently homogeneous dishes. Our journal also covers labels and raw versus cooked weights. The Yumlean guide adds detailed recipes and estimated macros; adjust these to the ingredients you actually use.