Effects of a time-restricted high- or low-fat diet on lipid absorption




Balderrama, Jesse, Jr.

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Background: Chronic high-fat diets and time-restricted feeding have been shown to impact multiple cardiometabolic parameters. The purpose of this work was to investigate the effects of timed macronutrient intake on lipid absorption. Methods: Adult male FVB/N mice were randomly assigned to one of 6 feeding groups (n=45, 7-8 animals/group) and kept on a strict 12h light: 12h dark feeding schedule (lights on at 10pm (Zeitgeber Time - ZT0) and lights off at 10am (ZT12)). Food was made available continuously to mice in the control ad libitum low-fat (CALF) and control ad libitum high-fat (CAHF) feeding groups. Mice in the control low-fat (CLF) and control high-fat (CHF) groups received low fat or high fat food, respectively, exclusively during ZT 12-16 and ZT 20-24. Mice in the early high-fat (EHF) group received access to high-fat food during ZT 12-16 and low-fat food during ZT 20-24. Mice in the early low-fat (ELF) group received access to the low-fat food during ZT 12-16, and high-fat food during ZT 20-24. EHF and ELF groups did not have access to food during ZT 16-20. Rodent diet foods were 45% kcal from fat or 10% kcal from fat in high-fat groups and low-fat groups, respectively. After 12 weeks of study protocol, fecal samples were collected over a 24h period. Lipid extractions were performed to quantify fecal lipid content. Plasma samples were collected during mice sacrifice and triglyceride concentration was quantified. Results: There was a significant effect of feeding group (p=0.0016) as well as a significant effect of time on fecal lipid content (p=<0.05). Cosinor analysis revealed that feeding groups CALF, CLF, EHF, ELF showed significant rhythmicity for fecal lipid content, with no rhythmicity in fecal lipid content for either group exclusively eating a high fat diet (CAHF and CHF). There was a significant difference in plasma triglycerides between feeding groups (F (5,24) = 13.14, p = <0.05). A Scheffe post hoc test revealed that fasting plasma triglycerides showed a trend toward higher concentrations in groups fed low-fat food. Conclusion: Chronic high-fat diets resulted in greater fecal lipid content and lower fasting plasma triglycerides compared to low-fat diets


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