ok so i need some help. approx 3 years ago started gaining weight and did the keto diet meaning no sugar and lots of heathy fats and protein. lost alot of weight looking and feelin great. then i went into major slumps and was diagnosed hypothyroid. been taking ndt with mixed results. i was taking 3.0 grains of naturethroid for a while feeling great with all my numbers top of range like everyone suggest. but i have noticed anytime i cut out carbs and especially sugar i immediately start feeling hypo.. and have to up my dose but whenev i eat sugar or just eat whatever my heart races like crazy and i feel extremly hyperthyroid. and almost cant tolerate any ndt. i actually cut it down to 1.5 grains. but then i got hypo symptoms with a racing heart anytime i eat sugar lol. i just want to find a steady dose. so i have completly eliminated sugar and carbs besides the occasional white rice. my heart feels super steady but im at 3.5 grains and still feel slightly hypo. my question is. is the carbs and sugar making my thyroid work better from the extra insulin causing me to get hyper. or is it increasing my antibodies or something. i have never tested positive for antibodies
ndt and no sugar: ok so i need some help. approx... - Thyroid UK
ndt and no sugar
and when my diet is normal it is a constant yo yo of feeling great hyper or hypo all in same day. but my weakness is cheescake and when i eat that my heart will race
Your body needs calories to boost t4 to t3 conversion.
The body needs carbs to convert. You need to find out just how low you can decrease your carbs without affecting your conversion. And, you can only do that by trial and error.
Sugar makes my heart race too. Not always though—which makes it a bit difficult to predict!
Sugar’s not good for anyone but I think starchy carbs probably get a bad rap (so long as they’re eaten in moderation). I think we just eat too many starchy carbs these days. Growing up, I perhaps used to have 3 pieces of potato on my plate. We never had pasta (no one did. Just wasn’t something anyone ate until I was in my late teens). And if we had a pizza we shared it between the four of us. Wouldn’t have dreamed of eating the whole thing.
So... 
Maybe put some more starchy carbs back in your diet? Not everyone does well on a low carb diet. Some people really thrive but I just feel exhausted. Wish I didn’t because I love how it stops me being hungry! But we are all different and it may be a question of trial and error.
Lots of sugar = racing heart for me too. 
Keto diets are bad for the thyroid! Your thyroid needs carbs to function. There are many articles on this and how it messes with T4 to T3 conversion. I find when my heart races after I eat something it's usually hypoglycemia. I can't touch rice, roast or fried sweet potatoes.
magsyh, I respectfully disagree with your comment that the Keto diet is bad for the thyroid. I was given the Keto diet over 30 years ago ( before anyone referred to it as Keto) I was given this diet by a very well respected Dr. who had studied this way of eating for years. I have followed this diet for the better part of 30 years. I am 70 years old and feel great and look years younger then 70. I am also hypothyroid and have been since way before I started Keto. The keto diet does not eliminate carbs. The carbs eaten on keto are high fiber vegetables and certain grains...not all though. There are a number of them available. Another food that is both carb and good fat are nuts. I also take NDT as my thyroid replacement.
Ramsfs10, I have been a KETO eater for over 30 years and also take NDT. I was hypothyroid way before Keto. I have had my weak times when I fall off my good way of eating and know the feeling that sugar gives me. It is proven with brain scans that sugar stimulates the brain in the same way cocaine does and the effect of sugar last longer then cocaine. I think this is what you are feeling when introducing sugar or carbs that break down into sugars after a nice long stint on high fat, protein, low carb. It's actually a HIGH. This is what is making your heart race and feeling like you are going hyperthyroid. I've experienced exactly the same thing. The effects of sugar ( the addiction that comes on quickly) is also what makes you feel like sh*# when you decide to give it up and go back on Keto. I hate to call Keto a diet...for me it's a lifetime way of eating.
yes i love keto. eat lots of healthy nuts vegtables avocados. meats. that is very interesting point on sugar. since geting well dosed on ndt i also cant tolerate caffeine as well. anything over one cup of coffee will make my heart race. compared to when i wasnt on meds i had to drink a gallon of coffee just to get through the day
When I have slipped off Keto and introduce sugar, I know I act like an addict. Last year I was driving home from grocery shopping...having bought very healthy Keto type foods to get back into eating healthy and I got such a sugar craving...I turned the car around and went back for some donuts! At that point, I had to talk myself down off the "sugar ledge". That is when I knew I had to get back to my healthy Keto way of eating.
Carb/sugar craving/highTSH - is there a connection?
Should I raise NDT? 
Should I increase my NDT?
How can I have hypo symptoms but a fast heart rate on NDT?
