Hi
I was diagnosed with an underscore thyroid over 8 years ago. Currently on 125mg of levothyroxine. Blood tests always different so dose goes up then down constantly.really struggling with weight gain, read on another site about eating a gluten free diet. Any truth in this ??
Allportlou A gluten free diet is recommended when you have autoimmune thyroid disease aka Hashimoto's. Have you had antibodies tested to find out if you have Hashi's? A gluten free diet is recommended to help reduce antibodies rather than for weight loss, but that would be a nice bonus 
When having blood drawn for your thyroid tests, do you always book the first appointment of the morning, fast overnight and leave Levo off for 24 hours? This gives the highest possible TSH which is what is needed when looking for an increase in dose or to avoid a reduction. It is also the only way that you can accurately compare test results.
Do you have your latest results to share? If so, post them, along with their reference ranges, for members to comment. If not then ask at your surgery for a print out, you are legally entitled to your results but they may make a small charge for paper and printing.
Allportlou,
If your GP alters your dose according to TSH levels your levels and dose will yo-yo. Instead of increasing dose to 150mcg say, then reducing it back to 125mcg 2 months later, suggest to your GP that you try 125/150mcg alternate days.
What are your most recent thyroid results and ranges? It will be impossible to lose weight if you are under medicated.
Some people have lost weight when they've adopted 100% gluten free diet probably because they eat less bread and cook from scratch. Watch out for gluten-free foods which are often high in sugar.
Hypothyroidism and Dieting
Dieting with Hashimotos 
change in medication 
tsh changes in result but no change in medication.
Help on readings, weight and diet ! 
