Random Number Generator based on specific constraints

I am a working on a nutrition spread sheet for people that have to meet certain protein and carbohydrate requirements. On sheet one of the spreadsheet there is a list of different foods all with an ID number. On the second sheet is a meal plan showing what you are supposed to eat. The goal is to eat food that has a combine total of 15-20 grams of protien and 30 grams of carbohydrates per meal. What i want this spreadsheet to do is randomly select items from sheet one that adds together to meet the protein and carbohydrates required. Currently you just look on page one and find the id number of the food you want and type that number into the item# column on sheet two and it automatically fills in the information. The problem is that you end up eating the same foods all the time. Would like to figure out how to program this to randomly select foods that add up to the correct values.