_________ to _________ ratio is greater than 2:1 in lipids.

Lipids are organic molecules composed primarily of carbon, hydrogen, and oxygen atoms.

In carbohydrates, the ratio of hydrogen to oxygen is typically $2:1$, similar to that in water.

In lipids, the proportion of oxygen is considerably lower compared to the amount of carbon and hydrogen. Therefore, the ratio of hydrogen to oxygen in lipids is always much greater than $2:1$.

For example, the chemical formula of a common lipid, tristearin, is $C_{57}H_{110}O_{6}$, where the hydrogen to oxygen ratio is $110:6$, which is significantly greater than $2:1$.

Answer: Hydrogen, oxygen