Question 1

How much protein do active adults actually need?

Accepted Answer

The 2017 ISSN Position Stand recommends 1.4–2.0 g protein/kg body weight/day for active individuals to support muscle protein synthesis and recovery. The Morton 2018 meta-analysis (49 RCTs, n=1,863) found benefits to lean mass and strength plateau at approximately 1.62 g/kg/day. UK Reference Nutrient Intake (RNI) of 0.75 g/kg/day is set for sedentary adults — substantially below athletic requirements. Distribution matters: ISSN recommends 0.25–0.40 g/kg per meal across 3–4 meals.

Question 2

Why is whey particularly effective for muscle protein synthesis?

Accepted Answer

Whey is digested rapidly, producing a fast and high plasma amino acid peak. It is rich in branched-chain amino acids (BCAAs), particularly leucine — the amino acid that triggers the mTORC1 signalling pathway driving muscle protein synthesis. A 25 g serving of whey delivers approximately 2.5–3 g leucine, at or above the leucine threshold (~2–3 g) needed to maximally stimulate MPS in young adults. Casein is digested more slowly and produces a sustained, lower peak. The combination of fast digestion and high leucine makes whey particularly suited to peri-workout use.

Question 3

Is whey isolate worth paying more for than concentrate?

Accepted Answer

Whey isolate is ~90% protein by weight and contains less than 1% lactose, while concentrate is ~80% protein and retains more lactose, fat and milk minerals. For lactose-intolerant users, isolate is meaningfully better tolerated. For everyone else, the practical difference for muscle protein synthesis is minimal — Morton's meta-analysis found total protein dose was the dominant variable, not the form. Isolate makes sense for cutting (more protein per gram), digestive sensitivity, or convenience. Concentrate is a perfectly adequate cheaper option for most people.

Question 4

Does whey damage your kidneys?

Accepted Answer

In adults with healthy kidney function, high-protein diets including whey supplementation have not been shown to cause kidney damage in any controlled trial. A 2018 systematic review of randomised trials concluded protein intakes of 1.2–2.4 g/kg/day did not adversely affect kidney function in healthy adults. The picture differs for those with pre-existing chronic kidney disease (eGFR <60), where lower protein intakes may be advised under specialist supervision. The 'protein damages kidneys' narrative is largely an extrapolation from the CKD population and is not supported in healthy individuals.

Question 5

When is the best time to take whey protein?

Accepted Answer

The classical 'anabolic window' (within 30 minutes post-workout) has been substantially weakened by recent evidence — Schoenfeld's 2013 meta-analysis found no significant difference in hypertrophy between immediate and delayed post-workout protein when total daily intake was matched. The contemporary view is that distribution across the day matters more than precise timing: aim for ~0.25–0.40 g/kg per meal across 3–4 daily meals. A whey serving within roughly 2 hours pre- or post-training is reasonable, but hitting your daily protein target is the dominant variable.

Question 6

Are whey proteins regulated for purity in the UK?

Accepted Answer

Whey protein is classified as a food and falls under UK food law (the General Food Law Regulation, retained from EU law). Heavy metal contamination (lead, cadmium, mercury, arsenic) has been documented in independent product surveys (e.g. Clean Label Project). For higher assurance, look for products with Informed Sport (LGC), NSF Certified for Sport, or Clean Label Project Purity Award certifications, which test individual batches for banned substances and contaminants. EFSA-authorised health claims apply to the constituent amino acids and to total protein for muscle maintenance and growth.

Grade	Health Outcome	Studies	Participants	Effect
A	Lean Mass and Strength with Resistance Training49 studies	49	1,863	Protein supplementation augments lean body mass and 1RM strength gains in adults performing resistance training. Effect plateaus at total intake around 1.6 g protein/kg body weight/day.
A	Acute Muscle Protein Synthesis (Leucine Threshold)12 studies	12	200	Whey produces a rapid, high plasma amino acid peak that maximally stimulates muscle protein synthesis at ~0.4 g/kg per meal in younger adults; older adults often need higher per-meal doses.
B	Satiety and Body Composition14 studies	14	800	Higher protein intake including whey supports satiety, reduces hunger ratings, and modestly favours fat loss over carbohydrate-matched controls during energy restriction.

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