One of the Gale databases that include reference books and periodicals (academic journals, magazines, and newspapers) along with a section on experiments. The journal Nature is included. A good starting point to identify a topic and to gather keywords and names of investigators for a Google Scholar search. Be sure to look closely at the Academic Journals.
Here is a listing of topics.
Here is listing of very, very basic science experiments.
This listing is more sophisticated.
Keyword searching is how you typically search Google Scholar, Google, and library databases. Think of important words or phrases (put quotation marks around the phrase) and type them in and see what happens.
If you're new to the subject, it may be helpful to pick up the terminology from secondary sources, such as a Wikipedia article or a general article from a library database. (A better keyword for "overweight" in a Google Scholar search might be "pediatric hyperalimentation".)
It's important for you to be systematic. Perhaps you want to start by keeping a written list of keywords. You'll notice that as you read articles or abstracts, you'll find addition keywords. Always look at the references at the end of a article for new keywords.