XPO should not automatically pre-load an associated collection when I only need to insert a new object into it

If I have the following two objects:
public class Product
{
   [Key(true)]
   public Int32 Key;
   public String Name;
   private Category _Category = null;
   [Association("Category-Product")]
   public Category Category
   {
      get { return _Category; }
      set {
         Category oldValue = _Category;
         _Category = value;
         OnChanged("Category", oldValue, _Category);
      }
   }
}
public class Category
{
   [Key(true)]
   public Int32 Key;
   public String Name;
   [Association("Category-Product"), Aggregated]
   public XPCollection<Product> Products
   {
      get { return GetCollection("Products"); }
   }
}
Then if I do this:
Product p = new Product();
p.Name = "test product";
p.Category = Session.DefaultSession.GetObjectByKey<Category>(1);
p.Save();
then what happens is that not only is category #1 loaded, every product in that category is loaded, and Product objects are constructed, potentially drawing in lots of other referenced objects as well. If that category is a popular category with thousands of products, that simple insert+update .Save() call turns into a big Select nightmare.
Is there a way to set up my classes so that unless I have previously loaded the Products collection on that category, it won't be loaded when I do the above code?
See also:
In a 1:N relation between two objects, setting the reference in the N side loads the collection in the 1-side, is this intended, can it be avoided?