The Amino Spiking Field Guide
The protein number on a tub is not measured by counting protein. It is estimated by measuring nitrogen — and there are cheap, legal ingredients that carry a lot of nitrogen without doing anything a protein does. This guide shows you the four tells, the arithmetic that catches them, and the one email that settles it.
Why the number can be true and still be wrong
Standard protein testing measures how much nitrogen is in a sample and multiplies by a fixed factor to estimate protein. It is a good method, and it has one exploitable assumption: that all the nitrogen came from protein.
Add a few grams of a cheap nitrogen-rich amino acid to the tub and the nitrogen reading rises. The lab reports more protein. The label prints a bigger number. Nothing illegal has happened. But the added material does not build muscle the way a complete protein does, and it costs a fraction of what whey costs.
This is amino spiking, sometimes called protein spiking or nitrogen spiking. It is not exotic and it is not rare. It is also completely visible on the label once you know the shape of it.
The four tells
Free amino acids listed inside the protein blend.
Look for glycine, taurine, creatine, glutamine, arginine or beta-alanine appearing within the protein blend on the ingredient list, rather than in a separate line further down. These are the cheapest nitrogen per dollar on the market.
Taurine is the clearest signal of the group: it is not used to build body protein at all. If it is inside the protein blend, it is there for the nitrogen, not for you.
The words “protein blend” with no breakdown.
“Whey Protein Blend (whey concentrate, whey isolate, glycine)” tells you the ingredients in descending order but never the amounts. The isolate you are paying for may be a rounding error behind the concentrate, and the glycine may be doing more for the label than for you.
A brand confident in its ratio prints the ratio.
No amino acid profile anywhere.
Every real whey manufacturer has a full amino acid profile for its material, because the supplier provides one. If a tub will not show you the profile — on the label, on the website, or on request — ask why. The profile is where spiking becomes obvious, because a spiked product shows a distorted amount of one or two cheap aminos and a thin showing of the expensive ones.
The leucine number is missing or low.
Leucine is the amino acid most directly tied to triggering muscle protein synthesis, and it is one of the expensive ones. A serving of quality whey lands somewhere around 2.5–3 g of leucine. If a tub claims 25 g of protein but will not tell you the leucine, that is a choice, and it is worth noticing which way it points.
The arithmetic: protein density
This is the check that needs no cooperation from the brand. Divide grams of protein by the serving size.
Example — a scoop of 32 g delivering 25 g protein:
25 ÷ 32 × 100 = 78%
Now compare that against what the raw material can actually do:
| What the tub says it is | Density you should see | If it comes in much lower |
|---|---|---|
| Whey protein isolate | 85–90% | It is not mostly isolate, whatever the front says |
| Whey concentrate / blend | 70–80% | Flavouring and fillers are taking up more room than usual |
| Casein | 70–80% | Same |
| Mass gainer | 15–25% | Expected — the rest is carbohydrate, by design |
Flavour, sweetener, cocoa and anti-caking agents legitimately account for a few grams per scoop, so a chocolate product will always read a little lower than an unflavoured one. A 15–20 point gap is normal seasoning. A 30 point gap is a question.
The number that actually matters: cost per gram of protein
Price per tub is meaningless. Price per serving is nearly meaningless, because servings are whatever the brand decides to call a scoop. The only comparable number is what you pay for a gram of protein.
$49.99 ÷ (30 × 25 g) = $49.99 ÷ 750 g = $0.067 per gram
Run it on three tubs and the ranking almost always changes from what the shelf price suggested. The cheap tub with 18 g servings frequently turns out to be the expensive one.
Do it in this order and it takes ninety seconds: density first, because it needs no information the label does not already give you. Then cost per gram, because it reorders the shelf. Then the amino profile, because by that point you know which tub you actually want to interrogate.
Where the confusion usually comes from
“Isolate is always better than concentrate”
Isolate is more filtered: more protein by weight, less lactose, less fat. That makes it better per gram and better if lactose bothers you. It does not make concentrate a bad protein — a well-made concentrate is a good protein at a lower price. The problem is never concentrate. The problem is concentrate sold at isolate prices under a blend label that hides the ratio.
“More protein per scoop is better”
Only if the scoop is the same size. A 40 g scoop delivering 30 g of protein is less impressive than a 28 g scoop delivering 25 g, and it disappears faster.
“Added aminos are a bonus”
They can be, when they are declared separately and dosed meaningfully — added leucine, for instance, is a real formulation choice. The distinction is whether the amino acids are counted inside the protein total. Declared separately and they are an addition. Counted inside and they are a substitution.
The copy-paste email
Send this to any brand, ours included. Three questions, and the reply is the audit.
Hi — I am comparing protein powders and had three questions about ________.
1. Can you send the full amino acid profile per serving, including leucine?
2. Are any free-form amino acids included in the stated protein content?
3. What is the ratio of isolate to concentrate in the blend?
Thanks.
Question 2 is the one that matters. A brand with nothing to hide answers it in a sentence. Anything that is not a plain yes or no is an answer of its own.
Every dose on our label is in the tub. That is the whole company.
We are a family manufacturer in Davie, Florida, and we will answer all three of those questions about our own products. Get our high-protein recipe book free — real food, real macros — plus 10% off your first order.
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Related reading: Best whey protein isolate (2026) · Isolate vs concentrate vs blend · Protein calculator · ISO^UP isolate
General information for healthy adults, not medical advice.