Californian scientists found traces of everything from caffeine and spices to skin creams and anti-depressants on 40 phones they tested.
We leave traces of molecules, chemicals and bacteria on everything we touch.
Even washing hands thoroughly would not prevent the transfer to everyday objects, the researchers said.
Using a technique called mass spectrometry, the University of California San Diego research team tested 500 samples taken from 40 adults' mobile phones and hands.
They then compared them to molecules identified in a database and produced a "lifestyle profile" of each phone owner.
Dr Amina Bouslimani, an assistant project scientist on the study, said the results were revealing.
"By analysing the molecules they left behind on their phones, we could tell if a person is likely to be female, uses high-end cosmetics, dyes her hair, drinks coffee, prefers beer over wine, likes spicy food, is being treated for depression, wears sunscreen and bug spray - and therefore likely to spend a lot of time outdoors - all kinds of things," she said.
Most of the molecules are thought to be transferred from people's skin, hands and sweat to their phone.
Mosquito repellents and sunscreens were found to linger for a particularly long time on people's skin and phones, even when they had not been used for months.
Previous research by the same team found that people who had not washed for three days still had lots of traces of hygiene and beauty products on their skin.
The study said the testing method could:
The researchers now want to find out more about the multitude of bacteria that cover our skin - and what they reveal about us.
Senior author Prof Pieter Dorrestein said there were at least 1,000 different microbes living on the average person's skin, in hundreds of locations on the body.

The institution, which is based in Edinburgh, has been sold to Macquarie Group for £2.3bn and will now operate under the name Green Investment Group.
The government said the deal ensures that all taxpayer funding invested in the bank has been returned, with a gain of around £186m.
It employs 50 people at its headquarters in the Scottish capital.
Another 85 work at its London office.
The bank was set up by the UK government five years ago to fund renewable and low-carbon projects.
Climate Change and Industry Minister Claire Perry said: "We led the world in setting up the Green Investment Bank and it is now being copied by others.
"Now that it's in the private sector, it will be able to operate on an international level to tackle the global challenge of climate change.
"It is also perfectly placed to help us finance green initiatives for our Clean Growth Plan and realise the commitments set out in the Paris Agreement."
The government said the Edinburgh office will be home to a new revenue-generating business.
It will also provide services to the green energy portfolios of both Macquarie and the Green Investment Group in the UK.
Vince Cable, who launched the bank in 2012 when he was business secretary, said its sale was "environmentally irresponsible".
"The bank has done an extremely good job in supporting renewable energy, energy efficiency and low-carbon projects," the Liberal Democrat leader said.
"It has managed to attract over £10bn of private investment in these sectors that would not otherwise have happened.
"At a time when business confidence is falling and the Conservatives are giving mixed signals on their commitment to the environment, this is the worst time to undermine investment in the green economy.
"The Green Investment Bank's environmental mission is in danger of disappearing under the ownership of a private Australian bank whose track record does not inspire confidence."
Molecules found on mobile phones reveal an astonishing amount about the owner's health and lifestyle - including their food preferences and medication.
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The sale of the Green Investment Bank (GIB) by the UK government has been completed.