what this error means The model backing the 'OdeToFoodDb' context has changed since the database was created?

I wish this helpful for you I found the answer in the comments on this post on Scott Guthrie's blog.
http://weblogs.asp.net/scottgu/archive/2010/08/03/using-ef-code-first-with-an-existing-database.aspx

Database.SetInitializer<Production>(null);

will help you Doh! moment, turns out the service wasnt using the same connectionstring as the other app. the reason the databases didnt look the same must be because earlier in development i started the main app with no connectionstring aswell, so it provisioned a local instance database for itself to use.
Then later when i was trying to use the service, it was trying to access the same database from earlier, and the model changed significantly since then.

To fix the issue you can do make sure that you don't have a database initialized. Only have to call it once so you could put it in a static constructor of your DbContext class

Database.SetInitializer<YourDbContext>(null);

To fix the issue you can do As mentioned by stuartd in the comments, doing the following resolves the issue:

Database.SetInitializer<ServicesContext>(null);

hope this fix your issue Entity Framework stores migration history and the state of your database model in a table called MigrationHistory.
This document has details on customizing that table.