To test for lipid is heat needed

No

Explanation:

Place two spatulas of the food sample into a test tube or 1 cm3 if the sample is liquid.

Add 2 cm3 of ethanol to the tube. Cover the end of the tube and shake the tube vigorously.

Allow the contents to settle.

Pour the liquid from the top of the mixture into a test tube half-filled with water.

Record the level of the food and whether the water is cloudy or clear.

As you can see no heat is needed

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.