Fatvaries

Fatvaries is a coined term used to describe variation and diversity in fat composition across biological systems and dietary contexts. In this sense, it refers to the range of fatty acids and lipid classes that can be present within a tissue, organism, or dietary fat source. The term is not part of a formal biochemical nomenclature and does not denote a single measurable parameter; rather, it encompasses aspects such as chain length distribution, degree of unsaturation, positional isomerism, and stereochemistry when relevant.

Etymology and usage: The term blends “fat” with “varieties” or “variations.” It first appeared in informal discussions and some preprints and is not widely standardized. As a result, definitions of what counts toward a fatvaries set can vary by study and discipline, which can lead to inconsistencies in reporting and interpretation.

Characteristics and measurement: Fatvaries characterization relies on lipid profiling methods such as gas chromatography–mass spectrometry (GC-MS) of fatty acid methyl esters (FAMEs) or broader lipidomics workflows. Common descriptors include mean chain length, saturation index, and the distribution of saturated versus unsaturated fatty acids, as well as the presence of unusual or dietary-specific fatty acids. Variation can arise from genetics, diet, physiology, and environmental factors.

Applications and caution: In nutrition and metabolism research, fatvaries is used to discuss interindividual and inter-tissue variability in fat composition, which can influence membrane properties, energy storage, and signaling pathways. Critics argue that fatvaries is vague and should be operationally defined to improve clarity and reproducibility in studies.

See also: Fatty acids, Lipidomics, Lipids, Fat metabolism.