Isocaloric Substitution of Dietary Carbohydrate Intake with Fat Intake and MRI-Determined Total Volumes of Visceral, Subcutaneous and Hepatic Fat Content in Middle-Aged Adults.

Nutrients. 2019;11(5)
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Obesity, a worldwide epidemic due to the availability of many unhealthy food options and limited physical exercise, is a known risk factor for many metabolic disorders. The aim of this study was to investigate the association of carbohydrate intake and isocaloric substitution with different types of fat as determined by magnetic resonance imaging (MRI). The study’s analysis was based on the KORA-FF4 study, the second follow-up study of the KORA Survey S4. A total of 400 individuals participated in the FF4 study, from which 283 participants were included in this analysis. Results indicate an association between fat accumulation at specific anatomic locations and macronutrient composition among the participants. The isocaloric substitution of carbohydrates with fat was associated with higher hepatic (related to the liver) fat content and visceral fat accumulation. Authors conclude that the study’s findings can contribute towards the long-lasting discussion about a diet’s optimal fat content.

Abstract

The present study investigated the association of carbohydrate intake and isocaloric substitution with different types of fat with visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and hepatic fat content as determined by magnetic resonance imaging (MRI). Data from 283 participants (mean age 56.1 ± 9.0 years) from the MRI sub study of the KORA FF4 study were included. VAT, SAT and total body fat were quantified by a volume-interpolated VIBE-T1w-Dixon MR sequence. Hepatic fat content was determined as the proton density fat-fraction (PDFF) derived from multiecho-T1w MR sequence. Dietary intake was estimated using information provided by two different instruments, that is, repeated 24-h food lists and a food frequency questionnaire. Replacing total carbohydrates with an isoenergetic amount of total fat was significantly positively associated with VAT and hepatic fat, while there was no significant association with SAT. The multivariable adjusted β-coefficient for replacing 5% of total energy (5E%) carbohydrates with total fat was 0.42 L (95% CI: 0.04, 0.79) for VAT. A substitution in total fat intake by 5E% was associated with a significant increase in liver fat content by 23% (p-value 0.004). If reproduced in prospective studies, such findings would strongly argue for limiting dietary fat intake.

Lifestyle medicine

Fundamental Clinical Imbalances : Hormonal ; Structural
Patient Centred Factors : Triggers/Isocaloric fat intake
Environmental Inputs : Diet ; Nutrients ; Physical exercise
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Blood ; Imaging

Methodological quality

Allocation concealment : Not applicable
Publication Type : Journal Article

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