Does a low-carbohydrate diet work best for Hashimoto’s disease? There are a number of diets out there claiming to be the best for Hashimoto’s thyroiditis but as with any condition, there is no single best diet for everyone. A recent paper entitled, “Effects of low-carbohydrate diet therapy in overweight subjects with autoimmune thyroiditis: possible synergism with ChREBP” looked at how effective a low-carbohydrate diet can be for Hashimoto’s disease. Let’s dig into what the researchers found.

180 patients with Hashimoto’s thyroiditis were enrolled in the study with a composition of 84 males and 96 females aged 30-45. All patients had blood tests done for TSH, Free T4, Free T3, anti-thyroid peroxidase (TPO) antibodies, anti-microsomal antibodies, and anti-thyroglobulin antibodies.

Body composition was also determined by body impedance analysis (BIA) which measures bodyfat percentage, total body water, and fat-free mass. Those of you who are patients of mine know we check this in the office with a scale that works through bioempedance and I also recommend a home scale to all virtual patients to do these measurements at home.

108 patients (control group) were put on a diet consisting of:

12%-15% carbohydrates

50%-60% protein

25%-30% fat

Foods consistend of leafy greens and “other types of vegetables” that were not considered to be goitrogenic. Goitrogenic foods can inhibit iodine utilization by the thyroid gland which can lead to goiter and thyroid imbalances. The authors do correctly note that cooking goitrogenic foods completely eliminates any goitrogenic effects they may have.

This control group was also instructed to avoid legumes, dairy products, bread, pasta, eggs, fruits, and rice. They were instructed to eat only lean white and red meats.

They followed this diet for only 3 weeks and then had bioimpedance testing done as well as all the original thyroid antibody and thyroid hormone tests.

The other group of 72 patients followed a simple low-calorie diet without any food restrictions. These patients were also retested after just 3 weeks with the exact same tests.
What did the study results show?
There were no statistically significant changes in TSH, Free T4, and Free T3 in either group after 3 weeks.

The group that ate the low-calorie diet but with no food restrictions only showed statistically significant changes in body weight, lean mass, and body mass index (BMI). We would expect this in virtually anyone eating fewer calories for 3 weeks. You’ll notice that they lost muscle mass which isn’t good and this is the main problem with dieting because losing muscle is not healthy.

This group also showed a statistically significant increase in thyroid antibody levels including anti-thyroglobulin and anti-microsomal antibodies but not TPO antibodies.

In contrast, the group that followed the restricted diet showed a significant decrease in all three thyroid antibody levels. This group also lost bodyfat, total body weight, and there was a reduction in BMI.

Goitrogenic intake of food in each group was taken into account but the authors did not state how these foods were prepared or the quantity consumed.

The authors conclude that this type of diet is anti-inflammatory in nature so it can help autoimmune thyroiditis which includes inflammation of the thyroid gland. They also note the effect on thyroid hormone receptors, more specifically the alpha receptor which is found in the liver and white adipose tissue involved in fat-burning in these regions of the body. This type of diet can affect gene expression in these areas in a positive way leading to more fat-burning.

The authors also briefly note the affect of thyroid disrupting chemicals on thyroid function which I...