Weight is, typically, only a constant struggle is you refuse to start on replacement thyroid hormones. Once your hormones are, again, optimal, gained weight should, either come off without much effort, or at least, come off "with" the effort you put in.
I lost 23 of my "hypo" pounds once I got my levels to a good place for me and while I didn't do a specific LCHF diet, I did begin adding more fats to my diet vs the low fat diet my doctor had been trying to keep me on. I, too, have pre-diabetes and my cholesterol levels were elevated due to hypothyroidism... Once on the higher fat diet, with optimal thyroid hormone levels, my cholesterol and blood sugar levels, both went back to normal.
You might want to ask your doctor about metabolic syndrome, which is a set of conditions, including high blood sugar, obesity, high blood pressure, high cholesterol and high triglycerides... You must have at three of the 5 conditions to be diagnosed with metabolic syndrome... This is what I was diagnosed with.
Weight problems are a signature symptom of hypothyroidism, so while the diet will certainly help control blood sugar levels and contribute to better health, in general, it won't prompt your thyroid to produce more thyroid hormones.
Thyroid hormones control metabolism (which controls weight), heart rate, body temperature, and other important functions. High cholesterol is also, often associated with hypothyroidism, so if you haven't had that tested, yet, you should.
Good luck...
Yes, there is a difference between Total T3 and Free T3. Total is an estimate of the total amount of T4 in your blood. Most of that is bound to thyroxine binding globulin (TBG) and thus biologically inactive. Only the small portion not bound by TBG, thus referred to as "free", is biologically active. Under some conditions more T3 is bound to TBG, and the Free T3 level is affected. Since Free T3 correlates best with hypo symptoms, it is important to always test for it, along with Free T4.
Looking at your latest test results, you are correct that there was a slight change in Free T4 level and none in Total T3 level, even after the increase in med dosage. The reason is that serum levels of thyroid hormone are the sum of both natural thyroid hormone and thyroid med. Increasing thyroid med dosage reduces TSH and natural thyroid hormone output. Only when TSH is essentially suppressed does serum thyroid total levels start to rise with increases in med dosage.
Even more important than thyroid test results, what symptoms are you having/
Yes, there is a difference between Total and Free T3... Most of the T3 in your blood is bound by protein and can't be used; only the Free (unbound) T3 can be used by individual cells... When you measure Total T3, you're measuring, both bound and unbound T3, but when you measure Free T3, you're measuring only that which is Free to be used by the cells.
Even though you're being tested for Total T3, your level is very low, which indicates that your Free T3 will be very low, as well.
It definitely looks like you need another increase in your medication... It's recommended that Free T4 be about mid range and yours is only at 30%, which considerably shy of mid range. Recommended levels for Free T3 is upper half to upper third of its range... you don't have a Free T3, but your Total T3 is only 6% of the range, which is on the floor of the range.
Have you discussed these results with your doctor yet? Is s/he willing to increase your dosage?
Do you have symptoms of hypothyroidism?
I forgot to mention my prior results on 10/23/15 (levo raised from 50 mg to 75 mg) the above labs are from 12/30/15
10/23/15 labs
T3- 81 ranges: 76-181
T4-1.0 ranges: 0.8-1.8
TSH-1.55 ranges: 0.47-5.5
12/23/15 labs
TSH .81 range .40-4.50
T4 Free 1.1 range 0.8-1.8
T3 Total 82 range 76-181