I'm sorry Phoebe. This may help you though. Sorry it's long. 8 years ago I went to the docs. She said losing weight and being a hypo is like 'pi$$ing in the wind'. Unquote. So I found out for myself and I am applying the following. I've lost nearly 3 stone in the last two years since I started (and that's with stop and starts and being ill for 13 years with no success). This is not a five minute fix but this list may help you too. I hope so. xxx
1: RT3 IS TOO LOW. stopthethyroidmadness.com/r... - this is a brilliant link and explains this ratio issue very well. I've used T3 to correct mine.
2: CARB CONVERSION IS COMPROMISED/FOOD INTOLERANCE. Not all calories are equal and this is especially true for carbs. Hypos can seriously struggle with some carbs as you note but pasta is particularly bad. Most diets recommend pasta. SEE point 5. Also if you eat wheat and are intolerant then this can cause weight loss to slow/stop too. SEE point 5.
3: INSULIN RESISTANCE - this can be corrected by a short walk each day but it may take a while. Just 30 mins if you can as briskly as you can. Anything is good though. No drugs will work as well as just a short walk every day.
4: LIPID IMBALANCE - cholesterol. If you have belly fat that won't shift your lipids are out of balance - a common problem for hypos. Note cholesterol problems for hypos differ slightly over 'normal' people making it a bit more complex and changing the composition. Belly fat is metabolically active - which can affect your whole body badly. But it should be easier to lose than normal body fat - it's proven to shift faster - unless you have a lipid problem and then it will not go until you're lipids are corrected.
5: LOW BMR. This can be >40% lower than a normal person. An active woman needs 2000 healthy calories per day. But if your BMR is 40% lower then this is 1200 calories for a maintenance level of weight. How do you lose weight with this? You have to drop your calories. So you go to 1000 calories (now half a healthy person's BMR). But you lower your BMR when you diet. And it drops again to 800 calories to maintain weight with exercise. Just one portion of the wrong carbs can add weight and cancel any weight loss because we're talking grams and hypos don't do well with start/stop metabolic burn - you have to eat something regularly throughout the day, almost impossible on 800 calories. --- So what do you do? Increase your BMR (it can be measured). This is not done through maximizing cardio (a common mistake) but muscle creation with extensive weights and resistance. You need as much muscle to fat as possible (and that doesn't mean turn into Rambo! lols). If you're an endomorph the problem is worse. The Gym instructor may not understand your body as a hypo. Be warned they are not trained on this.
If just ONE of the above 5 things is out of whack you can stop losing weight. But a hypo can have all five. I would have given anything for this list 8 years ago. In my experience and from what I've read, just taking thyroid hormone will not reverse the damage which has resulted in the above biological errors. You have to do these manually. But you MUST also have your thyroid hormone making you feel well. And then go through this checklist to see if you have anything on it.
ADDITIONAL TIPS: Check your temperature - your thermic level is very useful during weight loss - body heat is a major way to burn calories. Good luck xx