Do you just want a linebreak as part of the document text? Then you can encode just the LF character (0x0A --> 
 somewhere in some content text), for example. If you want to have an element in your XML document representing a linebreak, define that element (like you have with <food> and <calories> for example, and make your XML processor/consumer understand that element you have defined. How you would do that, and whether it actually makes sense to do it the way you want, i cannot tell. (I neither know the XML processor you are using, nor do i know the actual goal/result you are trying to achieve by placing something like <br/> at some arbitrary location inside your XML...)

As a side note: I kinda can't shake the feeling that it's not the XML document and structure that is really your problem, but rather whatever you use or however you are trying to present/render the food items. Because, honestly, from the XML in your Q it looks like it is just a XML document describing a list of items, but not describing anything layout-related. So, i would suggest you look at whatever you use/do to render the list of items and see how and to which degree you can configure/influence the renderer presenting the food items. If my feeling is right, the CSS-based approach you mentioned looks actually very sensible and reasonable compared to trying to introduce layout/presentation-related meta-information in the XML document (that itself isn't looking like it is meant to describe layout/presentation-related things...)