I think that you will need a 3rd table. I think it should be something like: Day, Consume, Food.
For a day you consume multiple food items. Therefore you will need a join table that stores the IDs of each food item and the associated main Day record ID.
Did you complete this project?
I am doing the same thing and I would really like to see your work.
Could I see a copy of this file please?
I never got it to work. I went back to Access. I am pretty good with Access (and VBA) and setting it up in Access was easy.
Mr. Vodka's description of a solution is equally applicable to MS Access as well as filemaker. The principle of using a join table for many to many relationships works in both database systems. (And access has subform and subreport structures that are very similar to Filemaker's portals.)
The difference is that I can drive subform & subreport structures without a table relationship. I can create an unbound text box on one form (or a value from a table) and use it to drive a "relationship" with the subform. As far as I know (and admittedly when it comes to FMP that isn't much), portals have to be driven by an actual relationship. Since this is just for me (i.e. no scale up to SQL Server), I can get away with this cheat.
Well, your SQL expresion defines your "table relationship" and that's why it works in Access. You've simply set it up in SQL instead of a relationship graph.
The same interface setup--but using different objects in place of the SQL--can be set up in filemaker.