In the Siberian hamster, seasonal weight loss occurs gradually over many weeks during autumn and winter. This is driven by a regulatory mechanism that is able to integrate duration of exposure to short days with the size of body energy reserves. After food restriction in short days, followed by ad libitum refeeding, the hamster does not restore to its former weight, but increases to a body weight defined by the length of time spent in short days. In this report, we show that components of the thyroid hormone system that are involved in seasonal weight loss change expression in response to 48h of starvation. Eight weeks in short-day photoperiod induced weight loss in the Siberian hamster. In the hypothalamus of these hamsters, type II deiodinase (D2) expression was decreased and type III deiodinase (D3) expression was induced, but there was no change in hypothalamic NPY or TRH gene expression. For the first time, we show that the thyroid hormone transporter, MCT8, is expressed in tanycytes and is increased in response to short-day photoperiod. A 48h starvation reversed the direction of gene expression change for D2, D3 and MCT8 induced by short day photoperiods. Furthermore, fasting increased NPY expression and decreased TRH expression. VGF, a gene up-regulated in short days in the dorsal region of the medial posterior area of the arcuate nucleus (dmpARC) was not changed by starvation. These data point to a mechanism whereby energy deprivation can interact with SD photoperiod on hypothalamic tanycytes to regulate components of the thyroid hormone system involved in photoperiodic regulation of seasonal physiology.