Explain in simple molecular terms what would have to be done to a plant oil to transform it to a trans fat.

When naturally occurring unsaturated fatty acids are altered by partial hydrogenation, they are converted to saturated fatty acids, which have the effect of straightening the chains and changing the physical properties.

Also during partial hydrogenation, some of the unsaturated fatty acids, which are normally found as the cis isomer about the double bonds, are changed to a trans double bond and remain unsaturated. Trans fatty acids of the same length and weight as the original cis fatty acids, still have the same number of carbons, hydrogens, and oxygens but they are now shaped in a more linear form, as opposed to the bent forms of the cis isomers.  Trans and cis are prefixes that mean opposite and same side, just like transgender people identify with a gender that is not in line with their biological sex, and cisgender people identify with their biological gender. Cis fat describes the fatty acids attached to the glycerol in triglycerides. Cis fats have hydrogen attached to the carbon chain just like trans fats, but at one, two, or more places on the chain, two hydrogen atoms attached on the same side, and the fatty acid chain gets bent, making the collection of fats less dense and therefore healthier for you and I. Trans fats have hydrogen atoms on alternating sides all the way down the chain, making them denser and solid at room temperature. In order to turn a plant oil (cis fat) into trans fat, the cis fat has to be blasted with hydrogen in order to turn the fatty acid chains from cis to trans. This adds more energy to the fats while also making them denser, which turns olive oil into a butter-like substance.

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carbohydrates are the body's preferred source of energy.