The result of the call is the food id which matches the barcode specified (0 if no match was found).
<?xml version="1.0" encoding="utf-8" ?>
<food_id xmlns="http://platform.fatsecret.com/api/1.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://platform.fatsecret.com/api/1.0/ http://platform.fatsecret.com/api/1.0/fatsecret.xsd">4384</food_id>