Hepatic Mitochondrial Energetics During Catch‐Up Fat With High‐Fat Diets Rich in Lard or Safflower Oil

Abstract

We have investigated whether altered hepatic mitochondrial energetics could explain the differential effects of high‐fat diets with low or high ω6 polyunsaturated fatty acid content (lard vs. safflower oil) on the efficiency of body fat recovery (catch‐up fat) during refeeding after caloric restriction. After 2 weeks of caloric restriction, rats were isocalorically refed with a low‐fat diet (LF) or high‐fat diets made from either lard or safflower oil for 1 week, and energy balance and body composition changes were assessed. Hepatic mitochondrial energetics were determined from measurements of liver mitochondrial mass, respiratory capacities, and proton leak. Compared to rats refed the LF, the groups refed high‐fat diets showed lower energy expenditure and increased efficiency of fat gain; these differences were less marked with high‐safflower oil than with high‐lard diet. The increase in efficiency of catch‐up fat by the high‐fat diets could not be attributed to differences in liver mitochondrial activity. By contrast, the lower fat gain with high‐safflower oil than with high‐lard diet is accompanied by higher mitochondrial proton leak and increased proportion of arachidonic acid in mitochondrial membranes. In conclusion, the higher efficiency for catch‐up fat on high‐lard diet than on LF cannot be explained by altered hepatic mitochondrial energetics. By contrast, the ability of the high‐safflower oil diet to produce a less pronounced increase in the efficiency of catch‐up fat may partly reside in increased incorporation of arachidonic acid in hepatic mitochondrial membranes, leading to enhanced proton leak and mitochondrial uncoupling.

Overfeeding Polyunsaturated and Saturated Fat Causes Distinct Effects on Liver and Visceral Fat Accumulation in Humans

“…A previous supplementation trial in postmenopausal women reported that a daily dose of 8 g PUFA (safflower oil) increased lean tissue and reduced trunk fat (48). In accordance, rats isocalorically fed with PUFAs (high in linoleic acid) gained more lean tissue and less fat compared with an SFA-rich diet, in line with similar studies (16,17,49,50). The mechanism behind these observations remains to be determined.…”

“…Concentrations of D-3-hydroxybutyrate were, however, if anything, lower with PUFAs than SFAs, thus not supporting a differential effect on hepatic fat oxidation. Animal studies have also indicated that SFAs, compared with PUFAs, lower brown tissue adipose activity and thermogenesis (16)(17)(18)(19)(39)(40)(41)(42)(43)(44)(45).…”

“…Cross-sectional data suggest that dietary fat composition could play a key role in liver fat accumulation with polyunsaturated fatty acids (PUFAs) inversely (13) and saturated fatty acids (SFAs) directly associated with liver fat and liver fat markers (14,15). In addition, animals fed highfat diets with PUFAs reduced body and liver fat accumulation compared with SFA diets (16)(17)(18)(19)(20)(21). In the recent HEPFAT trial, we showed that an isocaloric diet rich in PUFAs given for 10 weeks reduced liver fat content and tended to reduce insulin resistance compared with a diet rich in SFAs in individuals with abdominal obesity and type 2 diabetes (22).…”

Hypolipidemic and Hypocholesterolemic Effect of Roselle (<i>Hibiscus sabdariffa</i> L.) Seeds Oil in Experimental Male Rats

“…Several studies show that the composition of dietary fat could play a major role in liver fat accumulation with polyunsaturated fatty acids PUFAs adversely 25 and saturated fatty acids SFAs directly related with liver fat and liver fat biomarkers 26 . Animals fed high fat diets incorporated with PUFAs reduced liver fat accumulation compared to SFA diets 27 . In this respect, Bjermo et al 21 indicate that an isocaloric diet rich in PUFAs submitted for ten weeks reduced the content of liver fat and tended to reduce insulin resistance compared to a diet rich in SFAs in individuals with abdominal obesity and type 2 diabetes.…”

Polyunsaturated Fatty Acids Stimulate De novo Lipogenesis and Improve Glucose Homeostasis during Refeeding with High Fat Diet

“…In previous studies (Crescenzo et al, 2003; De Andrade et al, 2015), we observed that after a period of caloric restriction, when rats are refed with a low fat diet, they exhibit a reduction in energy expenditure and an increase in metabolic efficiency that give rise to an elevated rate of body fat deposition (even in absence of hyperphagia), together with a reduced insulin sensitivity (Crescenzo et al, 2003; Cettour-Rose et al, 2005). The above metabolic alterations are exacerbated by refeeding on a high fat diet (Dulloo and Girardier, 1992; Crescenzo et al, 2003, 2012; Marcelino et al, 2013). Indeed, it was shown that glucose homeostasis is impaired during refeeding with high fat diets rich in lard, mainly containing saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA), partly because the pathway of de novo lipogenesis is markedly inhibited in liver and white adipose tissue (WAT) (Marcelino et al, 2013).…”