Thyroid UK
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Overweight & Underactive!

Hi, I recently made a post about finding it very hard to lose weight when your over active & was advised to have my Thyroid tested so I'd be very thankful if someone can suggest what I need to be doing to lose weight or if something needs to be adjusted...

Vitamin B12 180-2000 ng/L = 477

Serum Folate 2.8-20 ug/L =2.9

Ferritin 20-300 ug/L = 78

TSH 0.20-4.50 mU/L = 1.4

Free T4 9-21 PMO1/L = 20

Total T3 0.9 - 2.4 NMO1/L = 1.5 250H

VIT D imm'assay 25-162 nmo1/L = 46

FREE T3 3.78 pmol/L 3.10 - 6.80

6 Replies

Hi Carol,

first - two disclaimers! I'm quite new to all things thyroid, plus I have a severe case of brain fog! So please don't take anything I say as gospel..

However, these are my thoughts:

1. "finding it very hard to lose weight when your over active" - I assume you mean under active here?

2. Your serum folate is only just within range so there is room to improve this. I understand ferritin needs to be at least 70 for thyroid hormones to work properly (both the ones your body manufactures and the ones you take as medication). Your VitD could also be a lot higher.

3. Your FT4, to me, seems high relative to your only just within range FT3. Others will reply who are more knowledgable, but that makes me think you're not converting T4 to T3 very well. There are nutrients you can take which will help this conversion, such as selenium. There is some information in this link about nutrients that help thyroid production and that help T4 to T3 conversion:

4. I've had lifelong weight problems, starting with anorexia nervosa then bulimia, followed by constant dieting and putting it all back on. My weight over the years has fluctuated by 7.5 stone. Eek. I would try yet another new diet, lose 3-4 stone, then put it back on again. In early 2016 I started a low carb, high fat regime, and I lost 3 stone in less than six months, without eating any less. In fact I'd say I probably finally eat a lot more, because at last my weight has stabilised and I no longer have to think about calories. I've started adding in more carbs now, as they are apparently pretty crucial to thyroid function, so I eat, for instance, sweet potato with my evening meal, and one or two pieces of fruit a day. But generally, my diet consists of meat, fish, eggs, avocado, nuts, olive oil, butter, cheese (with occasional forays in to cutting out dairy...) and masses of vegetables (less so the carby ones such as potatoes). I avoid polyunsaturated fats (for all sorts of reasons, I've also recently read that they can mess up thyroid function) and stick to coconut oil, lard, butter. I've also read that cutting calories is definitely not the right approach if you suffer with hypothyroidism. You really do NEED adequate calories.

5. You don't say whether you are on any thyroid drugs. If you are only on levothyroxine, it could well be that you'd benefit from taking some T3 too, if it is that you're not converting T4 very well. Others more knowledgeable will hopefully advise on this. T3 can also contribute to good metabolism because it's the active hormone, so that can also help reduce weight.

I wish you luck! :)

1 like

Hi ShinyB,

sorry I made a mistake yes I am underactive, I don't know why I put overactive, anyway thank you so much for your advice, it's a case of me learning a whole new way of eating, I think I eat relatively healthy but nothing fancy...

I've been on 100mg of Levothyroxine since diagnosed in 2009 & it's the same each time I get my yrly test I hear nothing else, then I mention my weight & it gets ignored.

I'm off on holiday soon to Goa, so all the veg & fish + Vit D for 10 days & see how I feel.

Thank You



Hi Carol, 100mcg is not an overly high dose yet your FT4 is high in range, with your FT3 still very low in range. I would think you're not converting T4 to T3 very well. I would explore the idea of taking some T3 if it were me. I wouldn't take further levothyroxine as if it's not converting to T3, that would probably just cause you more problems.

I've been taking T3 in addition to my levo for about 7 weeks now, and I've lost another 5lb :)

The holiday sounds wonderful - have a lovely time! :D



TSH is low-normal, FT4 is high in range but FT3 is low in range indicating poor conversion and that may be why you are struggling to lose weight. Ask your GP to increase dose. It may send FT4 a little over range but it will increase FT3.

The goal of Levothyroxine is to restore the patient to euthyroid status. For most patients that will be when TSH is 0.2 - 1.0 with FT4 in the upper range. FT4 needs to be in the upper range in order that sufficient T3 is converted. Read Treatment Options in Email if you would like a copy of the Pulse article to show your GP.



B12 is unlikely to be deficient.

Folate is low in range. You can raise folate by supplmenting folic acid or methylfolate.

Ferritin is optimal halfway through range but 78 is unlikely to be a problem. You can raise ferritin by eating more iron rich food.

VitD is insufficient. Vit D is replete >75 and optimal 100 - 150. I would supplement 5,000iu D3 daily x 8 weeks then reduce to 5,000iu alternate days and retest late May. Take vitD 4 hours away from Levothyroxine.


Your FT3 is very low. Ask GP to increase your Levo 25mcg (they may not agree)

Your vitamins are all on low side. Vitamin D especially

Getting your vitamin levels optimal us first step

Vitamin D aiming for around 100nmol

Better You vitamin D mouth spray is good as avoids poor gut function

Perhaps take 3000iu strength 2 x per day for a month, then once a day for 3 months and retest £28 postal kit

Important to take magnesium and vitamin K2 Mk 7 too

Detailed supplements advice on Low vitamins here

Eating liver once a week should help ferritin

B12 and folate - a good vitamin B complex (eg Igennus Super B complex and possibly also sublingual B12 lozenges (eg Jarrow 1000mcg once day)

Only start one supplement at a time and wait 2 weeks to see reaction before adding another

If you are taking vitamin B complex, or any supplements containing biotin, remember to stop these 3-5 days before any blood tests, as biotin can falsely affect test results

You might also consider trying a strictly gluten free diet. Many even without antibodies have found it helps. You originally had Graves so may still have antibodies present and/or benefit from gluten free diet

Retest 2 -3 months time - see if FT3 is improved or still too low

All thyroid tests should be done as early as possible in morning and fasting and don't take Levo in the 24 hours prior to test, delay and take straight after. This gives highest TSH, lowest FT4 and most consistent results

Dr Toft, past president of the British Thyroid Association and leading endocrinologist, states in Pulse Magazine,

"The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.

In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l.

Most patients will feel well in that circumstance. But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.

This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)."

You can obtain a copy of the articles from Thyroid UK email print it and highlight question 6 to show your doctor

 please email Dionne: at

Professor Toft recent article saying, T3 may be necessary for many especially note his comments regarding current inadequate treatment following RAI or thyroidectomy


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