The latest versions of the MyFitnessPal apps for iPhone, iPad and Android can alert you if you have not yet logged food for a particular meal, or for all meals. You can choose the time of day that you would like to receive these reminders.
To begin, in the Menu (or "More" page) tap "Reminders" (the icon is an alarm clock). Your current reminders are listed on this page.
To add a reminder, tap the "+" button in the top right corner. Select a Reminder Time and a Reminder Type by tapping the two fields on this screen. When the conditions for the reminder are correct, tap the "✓" button.
If the conditions of the reminder are met on a given day, the app will push an alert to your device with the appropriate message. Please make sure your general push notification settings are set to allow MyFitnessPal to generate notifications.