At Newcastle University, experts have shown that the age old weight unit of kilogram has put on weight.
Using a state-of-the-art Theta-probe XPS machine - the only one of its kind in the world - the team have shown the original kilogram is likely to be tens of micrograms heavier than it was when the first standard was set in 1875.
The original kilogram - known as the International Prototype Kilogram or the IPK - is the standard against which all other measurements of mass are set.
Stored in the International Bureau of Weights and Measures in Paris, forty official replicas of the IPK were made in 1884 and distributed around the world in order to standardise mass. The UK holds replica 18 at the National Physical Laboratory (NPL).
But despite efforts to protect the IPK and its duplicates, industrialisation and modern living have taken their toll on the platinum-based weights and contaminants have built up on the surface.
Now, Professor Peter Cumpson and Dr Naoko Sano have used cutting-edge X-ray Photoelectron Spectroscopy (XPS) to analyse surfaces similar to the standard kilogram to assess the build-up of hydrocarbons - and how to remove them.
They revealed how giving the kilogram a suntan could be the answer to helping it lose weight.
"Statute decrees the IPK is the kilogram," lead researcher Peter Cumpson, Professor of MicroElectroMechanical Systems (MEMS) at Newcastle University said.
"It doesn't really matter what it weighs as long as we are all working to the same exact standard - the problem is there are slight differences. Around the world, the IPK and its 40 replicas are all growing at different rates, diverging from the original.
"We're only talking about a very small change - less than 100 micrograms - so, unfortunately, we can't all take a couple of kilograms off our weight and pretend the Christmas over-indulgence never happened," he said.
The kilogram is one of the seven SI base units from which all other units can be derived and is the only one which is measured against a physical object - the IPK - all others are standardised against known constants.
The findings are published in the journal of Metrologia.