Beside the health and food bar are up to 3 icons for food you've eaten. If one is blinking it means its effect is halfway gone and you can now eat more to fully refresh the hp/stamina boost from it, and/or eat another food, or let it fully expire. You don't ever starve, but without eating your food and stamina go back down to minimum and without at least a single food item you don't heal.
The only other thing that might blink down there is an indicator you've been poisoned and are taking damage over time.