Intermittent fasting tracking works differently in FoodNoms than in other apps. FoodNoms doesn't require you to manually start and stop a timer. Instead, FoodNoms automatically calculates your fasts by measuring the time between each meal.
Whether or not you met your fasting goal on any day is determined by the fasts that occurred on that day. For the first fast of the day, the entire duration of the fast is counted, even if the fast began on an earlier day. For the last fast of the day, any time after midnight is not counted.
See "How do I create and edit goals?" to learn how to create an intermittent fasting goal.