If you've been noticing that Mary-Kate and Ashley Olsen have been piling on the micrograms in recent weeks, a US gossip magazine has unearthed the horrible truth - a barista has been putting full-cream milk in their non-fat lattes.

The story, which is sure to send a chill down the spine of fat-fearing caffeine consumers everywhere, said a former barista at a Starbucks in West Village, New York, had been spiking the rake-thin twins' coffees with full fat milk.

"The barista thought the Olsens were too thin, so whenever they ordered their usual drink, he would replace the skim-milk with full-fat!" tittered an anonymous "source".

The twins always ordered 'grande nonfat lattes" from the US coffee chain, the magazine wrote.

When approached for comment a spokesperson for the Olsen twins, who began their careers as nine-month-olds on the American sitcom, Full-House, said: "This is ridiculous."

Fair comment, one would think.