Dieting Software for new internet site

I am creating a website for people with Type 2 diabetes.? I want them to be able to input the foods they eat or want to eat, and get the calorie and other nutrient information (fat, protein, cholesterol and carbohydrate content per serving) for the foods or meals they choose.? I would like them to be able to substitute various foods as they build a meal knowing how many calories etc is in it. If they find, the meal they built is too "heavy" they should be able to substitute a lower calorie food. There is a free USDA database that can be accessed online to get the calorie and other nutrient info. The new software must be able to seamlessly connect to and download the requested information (calories, fats, protein etc) or you must be able to download the appropriate parts of the data base into our system. I am not asking for someone to re-invent the wheel. This has been done before. If you Google "dieting software" you will see that others have done it.? I'm looking for someone to reverse engineer what has already been done BUT NOT COPY any specific already existing software. I want to adapt and make it easier for viewers to use.? I will supply the url for USDA database mentioned above. I will pay for any short-term membership fees needed to scout out existing sites with similar software to get an idea of what features to offer. In the best of all worlds, you'll find one system offers x y and z benefits and other offers x y and w (something different) as benefits or ways of providing the info. Put them together with a more elegant coding scheme and we will have created a new entity.? Users should be able to download or print out the meals they "build" complete with the nutrient info. They should be able to save the data to their online account at my site. ## Deliverables I forgot to mention that my site is a WordPress site. I will be using Wordpress not just for the blog but for other pages too.