She is a drop dead gorgeous mare but she really needs a blood panel etc. to determine her thyroid levels and so forth. If she has what her body says she has (insulin reistance, thyroid level issues, even cushings and so forth) lack of treatment could lead to founder.
Get the vet out and let us know what the test results are. She is really lovely and worth the effort of treatment if the results turn out to be what we have guessed here!!!