Light is the main factor influencing food intake patterns in rats, not corticosterone. Adrenalectomy did not affect food intake in rats exposed to alternating light and dark cycles. In continuous light, food intake remained consistent regardless of corticosterone levels. Adrenalectomy led to smaller brown adipose tissue weight but did not affect protein content. Adrenalectomy increased purine nucleotide binding to mitochondria in brown adipose tissue, which was reversed by corticosterone.