We all know freshly prepared, nutritionally balanced meals are best for us and processed foods should ideally be restricted to the occasional treat. Yet experts warn us ultra-processed foods or UPFs are a growing health hazard. The term, introduced in 2009 by a group of Brazilian researchers, describes the most industrially compromised foodstuffs. But what exactly are they – and what's so bad about them? 

Click or scroll through our gallery to discover what UPFs are, and the foods experts say we should avoid the most.

We've based our ranking on the health credentials of each food, taking guidance from a registered nutritionist.