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Why can fats be made from carbohydrates, proteins, or other food sources?

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Synthesis of palmitate — Fat Palmitic acid is one of the most prevalent fatty acids occurring in the oils and fats of animals; it also occurs naturally in palm oil. It is generated through the addition of an acetyl group to multiple malonyl groups connected by single bonds between carbons. This structure forms a saturated acid—a major component of solid glycerides.

Fats can be synthesized from carbohydrates, proteins, and other food sources because these nutrients can be broken down into common metabolic intermediates, specifically two-carbon units known as acetate (or acetyl coenzyme A).12

The process of forming fat, known as lipogenesis, relies on these acetate units as building blocks. While carbohydrates are directly converted into these fragments through metabolic pathways, proteins and other sources can also be converted into acetate through their own respective catabolic processes. Once these acetate units are available, they are enzymatically linked together in a stepwise fashion to build fatty acid chains, which are then used to form glycerides.13452

Because the body can derive the necessary two-carbon precursors from various food sources, it is capable of synthesizing fat indirectly from any nutrient that can be metabolized into acetate. This allows the body to store excess energy from a diverse diet as adipose tissue, which serves as a vital energy reserve.164