Need to fetch data from a directory website

Hi I want to build an app similar to LoseIt. It’s a fitness app that logs meals organized by group and category along with exercise and other activities. It measures your calorie intake and exertion. I’m assuming it’s all built around a database of food and exercise with their respective calories consumed/burned/duration. Not sure how to build a similar database in Bubble and have the data fetched by users for input in their personal log, Any idea where to begin? Any assistance would be great!