FITGIRL / Ingredient library
Whey protein isolate
Content reviewed:
Ingredient information is not a product efficacy study. A publication, traditional use or a link to an ingredient does not authorise a health claim. [4]
Identity & classification
WPI is a concentrated milk-protein fraction, including beta-lactoglobulin and alpha-lactalbumin. The protein percentage of an ingredient is not necessarily the percentage of the flavoured finished powder. [1] [2] [3] [4]
Natural origin
Milk. Whey can be separated during cheesemaking or obtained through milk fractionation. Milk allergy remains relevant even when lactose is reduced. [1] [2] [3] [4]
History & background
Membrane separation enabled whey to become an ingredient with a controlled protein concentration instead of only a liquid dairy coproduct. [1] [2] [3] [4]
Production methods
Filtration concentrates proteins while removing part of the water, lactose and minerals. Further purification and drying yield isolate. The exact FitGirl process is not documented. [1] [2] [3] [4]
FitGirl raw material: the supplier, country of origin, batch specification and manufacturing process have not been independently verified. General production methods below do not establish the origin of this product.
Nutritional properties
Protein quality depends on digestibility and the indispensable amino-acid pattern. Whey contains the nine indispensable amino acids, including leucine, isoleucine and valine (BCAAs). No batch-specific amino-acid analysis is available for this product; precise leucine quantities are not inferred. [1] [2] [3] [4]
Food & sports nutrition
Count the protein in the prepared portion alongside meals. Adding milk changes the nutrition and allergens compared with preparing the powder in water. [1] [2] [3] [4]
Research & limitations
A reference intake describes a population need; it is not a trial of a branded product or a guarantee of a particular training result. [1] [2] [3] [4]
Approved health claims
Protein claims require the finished food to meet the “source of protein” condition: at least 12% of its energy from protein. “High protein” requires 20%. This must be assessed per formula and preparation, not inferred from the name “isolate”. See the product page for its verification status. [3] [4] [5]
Scientific references & product sources
- Tetra Pak (n.d.). Dairy Processing Handbook — Milk and whey fractionation
- EFSA NDA Panel (2012). Scientific Opinion on Dietary Reference Values for protein. EFSA Journal 10(2):2557 · DOI: 10.2903/j.efsa.2012.2557
- European Commission (2012; consolidated 2025). Regulation (EU) No 432/2012 — Annex: authorised health claims and conditions
- European Parliament and Council (2006). Regulation (EC) No 1924/2006 — Articles 5, 6, 10, 28 and Annex
- European Commission (2026). EU Register of nutrition and health claims
