of lean protein, fruits, and vegetables and which excludes dairy, legumes, processed food, grains, and sugar. After 45 days I had lost 20lbs.Earlier this year I did a 30 day Paleo challenge. I stuck to this diet that is mainly comprised of lean protein, fruits, and vegetables and which excludes dairy, legumes, processed food, grains, and sugar. After 45 days I had lost 20lbs.
Okay, so what does this have to do with hypothyroidism? I had my annual check up with my doctor and she was surprised to see I weighed 20lbs less than I was at my last visit. She immediately asked if I felt any different or if my symptoms of hypothyroidism had returned. I told her not 
that I know of, though of course I would love to be able to blame some of my crankiness on it if I could ;-)
She determined that I should definitely be tested to make sure I still require the same amount of synthetic hormone. After a quick blood test and a 24 hour lab result wait I was notified that I'm still doing well on my levels.
So for me, my thyroid levels remained within reason through pregnancy and dramatic weight loss.
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Hypothyroidism During Pregnancy