Some models you might look at include:
Planetary model
The
Bohr Model <http://csep10.phys.utk.edu/astr162/lect/light/bohr.html>
or click on the <Next> button and see Bohr's Model of an Electron
Wave
DNA double helix
DNA
Molecule: Two Views <http://www.accessexcellence.org/AB/GG/dna_molecule.html>
Computer model of the human body
Human--A Computer
Model of the Human Body <http://www.physiol.cam.ac.uk/misc/human.htm>
Bioscience models
Models in Medicine and
the Biosciences <http://www.shodor.org/master/biomed/>
You can make a model based on observations that you can make, but you can also make a model that includes observations from other people by doing research into what other people have done. From the research that you have done, list the variables that you can measure and the ones that you have read about other people measuing and then mark those variables that you would include in a model. There are two main criteria for choosing variables for your model:
You can get quantitative data on the variable, and The variable is important in the study of obesity.