The wholesale price of whey protein has risen far enough, fast enough, that gym-goers have given it a name. Among some of them the increase is now called proteinflation.
According to the global market intelligence platform Expana, the European price of one widely used type of high-protein whey was 130% higher in late August than a year earlier, and more than four times its level three years ago.
There is no equivalent UK measure, but Expana says the UK market is closely linked to mainland Europe, where some British businesses source their whey protein. Other dairy proteins have also become more expensive: another type of whey protein is up 60% over the year, and one type of milk protein concentrate is up 80%.
The cause is a familiar one. Demand has broadened well beyond the bodybuilders the category was once associated with, and supply has not kept pace. Food manufacturers now offer high-protein versions of everything from bagels to water.
Manufacturers say increasing production takes time and is costly, because high-protein whey requires specialist processing and drying equipment. Some are adapting instead, changing recipes or looking for cheaper sources of protein.
Warrior, a UK sports nutrition company, is one of them. "Our whey protein powder was £12.50 on the shelf last year. We've put that up to £17.99 and we're still subsidising that from other aspects of the business," says its founder, Kieran Fisher. The company is launching a product using other sources of protein, which Fisher says cost around half as much as whey.
The effects reach beyond the fitness market. Dairy proteins are used in infant formula, and Expana says higher dairy protein costs have contributed to price rises there too.
There are early signs of adjustment. Wholesale prices for high-protein whey have begun to level off over the past couple of months, although they remain far above where they were a few years ago.
One component of the new demand deserves separate attention, because it does not behave like the others. Weight-loss drugs such as Wegovy and Mounjaro have added a further source of it. People taking these drugs typically eat less, and are often encouraged to make sure they get enough protein while losing weight in order to preserve muscle.
This newspaper has checked that sentence twice and can confirm it says what it appears to say. A market in food ingredients is being tightened by customers who are eating less of them.
The Department of Unnecessary Research has classified the result and believes it to be novel. Demand for protein now moves inversely to appetite, which makes it the first agricultural commodity whose consumption is driven by the decision not to consume.
Our analysts have modelled the curve forward. If demand rises as eating falls, the theoretical peak of the protein market occurs at the point where nobody eats anything at all, and the sector is currently some way short of that ceiling.
The product range confirms the direction. The category began with powder, which is food with the water taken out, and has since produced high-protein bagels, which are food, and high-protein water, which is water.
Each step removes a little more of the meal and leaves the nutrient behind. The specialist drying equipment that manufacturers say is the bottleneck exists to do exactly this, and there is a limit to how much of anything can be removed.
At that limit the category arrives where it has been heading since the first tub: a protein with nothing attached to it, priced by the kilo, sold to people who are not eating.