title: Accumulation of polyunsaturates is decreased by weight-cycling: whole-body analysis in young, growing rats.
abstract: Whole-body fatty acid analysis in rats has previously shown that 50-70% of dietary linoleate and alpha-linolenate is beta-oxidized to CO2 and that this value increases with refeeding after a single episode of fasting. Our hypothesis was that repeated fasting-refeeding or weight-cycling would increase the beta-oxidation of linoleate and alpha-linolenate thereby depleting their whole-body levels. In rats consuming 3% energy as linoleate and 0.15% energy as alpha-linolenate during a 16 d balance period, 19% of the linoleate consumed accumulated in weight-cycled rats compared with 34% in the free-fed controls (P < 0.01). Similarly, 11% of the alpha-linolenate consumed accumulated in the weight-cycled rats compared with 22% in the controls (P < 0.01). Arachidonate and docosahexaenoate also accumulated to lower extents in the weight-cycled rats than in the controls. In contrast, whole-body accumulation of palmitate, stearate and oleate was not different between the weight-cycled group and the controls when measured as a proportion of intake or relative to weight gain. Thus, whole-body depletion of linoleate and alpha-linolenate did not occur per se but the partitioning of linoleate and alpha-linolenate was significantly altered by weight-cycling resulting in lower whole-body accumulation and higher apparent oxidation of all polyunsaturates especially linoleate and alpha-linolenate.
authors.affiliation: Department of Nutritional Science, University of Toronto, Ontario, Canada.
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Chen
authors.forename: C R
authors.initials: CR
authors.lastname: Menard
authors.forename: S C
authors.initials: SC
authors.lastname: Cunnane
mesh_terms: D000818:Animals; D001823:Body Composition / Q000502:physiology*; D005215:Fasting / Q000502:physiology*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D005502:Food; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley; D017962:alpha-Linolenic Acid / Q000378:metabolism
chemical_list: D005231:Fatty Acids, Unsaturated; D008041:Linoleic Acids; D017962:alpha-Linolenic Acid; D019787:Linoleic Acid