What does junk food do to your body?
With so many different foods out there it can be hard to know what's healthy and what's not.
But food expert Doctor Radha Modgil has been explaining what effect junk food can have by taking Newsround reporter Ricky inside the human body.
It's all part of Newsround's big food week where showed one out of three eat unhealthy foods like chocolate, crisps and take away more than three times a week.
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