The study looked at how not having enough zinc in the diet affects the thyroid hormones in rats, and what happens when zinc is added back in. Rats were split into different groups with varying zinc levels in their diets. The results showed that low zinc levels led to lower levels of a thyroid hormone called FT_3, but adding zinc back in brought those levels back to normal. However, another thyroid hormone called FT_4 was not affected by the changes in zinc levels. In conclusion, not having enough zinc can lower certain thyroid hormones, but others remain unaffected.