Thyroid UK
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I'm scared I'm developing a serious problem + food because I can't lose weight, even when eating under 600cals for days. Why can't I lose?

If I eat any more then I feel so guilty and so full that I just have to get it out of me. I tried talking to my doctor about my inability to lose weight and she just told me to "chill". It is making me so depressed that I am not coping at all. I would take St Johns Wort but it says that interferes with thyroxine uptake. I can't stand this fat all over my body. It is disgusting.

4 Replies

Please be reassured, it is certainly not you that is at fault.

There is scientific proof that being on levothyroxine (with a dose which keeps the TSH within the reference range) many gain weight. These are extracts and link:-

In the study that Julian Kesner cited, Fox et a1.[2] included 2,407 Americans. The study subjects’ TSH levels were all in-range. The researchers found that at baseline, the average body weight of women with TSH levels in the lowest quarter of the range was 142.2 lbs (64.5 kg); the average weight of women in the highest quarter of the range was 154.8 lbs (70.2 kg). The average weight of men whose TSH levels were in the lowest quarter of the range was 182.5 lbs (82.8 kg), and men in the highest quarter of the range weighed on average 188.7 lbs (85.6 kg). That is, the higher the TSH levels, the heavier the people were.

Fox et al. noted that with increased TSH levels, women gained more weight than men did, although both sexes gained. The researchers conjectured that women may accumulate more fat because fat oxidation is faster in men. At follow-up 3.5 years later, increases of the TSH level within the reference range “was strongly and linearly associated with weight gain.”

Other researchers have also reported that TSH levels—even in-range levels—were associated with obesity. A study of 4,082 Danish people with reference range TSH levels showed a positive correlation between the TSH levels and body mass index.[3] The researchers concluded, “Even slightly elevated serum TSH levels are associated with an increase in the occurrence of obesity.” (Italics mine.)

The three studies I mention above were published in 2005,[3] 2007,[4] and 2008.[2] They were published in the long-gone wake of a 2000 report from the journal Thyroid.[5] In that study, which has largely been ignored by the endocrinology specialty, researchers compared the treatment of hypothyroid patients to that of thyroid cancer patients. They found that hypothyroid patients on T4 replacement doses (dosages of thyroxine that keep the TSH within range) gained weight. In contrast, thyroid cancer patients didn’t take replacement doses of T4; instead, they took doses of T4 high enough to suppress their TSH levels. And they didn’t gain weight. The researchers concluded that T4 replacement was in fact the cause of the hypothyroid patients’ weight gain: “The excessive weight gain in patients becoming hypothyroid after destructive therapy for Graves’ disease suggests that restoration of serum TSH to the reference range by T4 alone may constitute inadequate hormone replacement.”

This is from Dr Toft who was President of the British Thyroid Association and a colleague but they still don't change their policies. Is it because it is mainly females who gain weight?:-

Beckett and Toft also wrote, ". . . our findings are supportive of growing evidence that the current policy for treatment of hypothyroidism with T4 alone and in a dose that restores serum TSH concentrations to the reference range may be flawed, at least in some patients.


On the TSH-suppressive doses of T4, the now hypothyroid cancer patients didn’t gain weight. Graves’ disease patients used T4-replacement doses—doses that kept the TSH within the current reference range. They were matched with the cancer patients for age, sex, and severity of hyperthyroidism before antithyroid therapy. The patients on T4-replacement after becoming hypothyroid gained a significantly greater amount of weight.[11]


As we are hypothyroid, our metabolism is very slow and no matter what some may do, the weight may not reduce.

If your TSH is 'within range' ask your GP if she could add some T3 to your T4 to see if that raises your metabolism as T3 is the active hormone our body needs. Also tell her studies have been done which proves, for many people on levo, that they gain weight. Dr Toft also says that some need a low or suppressed TSH to feel better (it doesn't mention weight). If your GP doesn't believe about adding T3 we can provide her with an article which says so.


Hi If on treatment or not,be sure to have a Free T3 test, if this is low even in range, often you need T3 with T4 to bring it up. Mostly the cause of excess weight if Hypo.Common for the body not to convert enough T4 ( levo?) to FT3.If T4 high in range, even more likely,

Be sure to have the other tests too.



You could be on the wrong thyroid medication or you could need an increase of what you are already on. I tried Levo and NDT and they made my symptoms worse.

Last September I tried T3 (I self medicate)and in three months I lost over 2 stone and my brain is much sharper. As soon as I reduce my T3 (I'm on 150mcg) I can't think straight again and my weight starts piling on again even though I don't eat much. As soon as I increase my T3 again the weight comes off without trying and my brain becomes sharp again.


600 calories will put your body into starvation mode and u will not lose anything . Small meals 5 times a day. Protein , good low Gi carbs and good fats . You will get there

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