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β-Oxidation of linoleate in obese men undergoing weight loss123

by Stephen CCunnane, RobertRoss, Jody LBannister, David JAJenkins

Abstract: ABSTRACTBackground:In animals, the whole-body content and accumulation of linoleate can be measured and compared with its intake to determine linoleate β-oxidation. This method can also provide quantitative information about the β-oxidation of linoleate in humans.Objectives:The objectives of the study were to 1 ) use the wholebody fatty acid balance method to quantify whole-body concentrations of linoleate in humans, 2 ) estimate the distribution of linoleate between adipose and lean tissue, and 3 ) assess the effect of weight loss on linoleate stores and β-oxidation in obese humans.Design:Nine healthy obese men underwent supervised weight loss for 112 d (16 wk). Magnetic resonance imaging data and fatty acid profiles from fat biopsies were both used to determine linoleate stores in adipose and lean tissue and in the whole body. Linoleate β-oxidation was calculated as intake − (accumulation + excretion).Results:Mean weight loss was 13 kg and linoleate intake was 24 ± 6 mmol/d over the study period. Whole-body loss of linoleate was 37 ± 18 mmol/d, or 28% of the level before weight loss. Combining the intake and whole-body loss of linoleate resulted in linoleate β-oxidation exceeding intake by 2.5-fold during the weight-loss period.Conclusions:All dietary linoleate is β-oxidized and at least an equivalent amount of linoleate is lost from the body during moderate weight loss in obese men. The method studied permits the assessment of long-term changes in linoleate homeostasis in obese humans and may be useful in determining the risk of linoleate deficiency in other conditions.
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Obese men were put on a calorie restricted diet (1,000kcal/day deficit) and exercise program for 16 weeks. Weight loss was 13 +- 4.9kg. Only up to 30% fat were allowed on the diet. Before and after weight loss, adipose biopsies and blood samples were taken. They also took full-body MRIs. Adipose linoleic acid changed from 12.7 ± 1.6 to 12.0 ± 1.3.