Proton magnetic resonance spectroscopy reveals increased hepatic lipid content after a single high-fat meal with no additional modulation by added protein

Abstract

Background: Fat accumulation in nonadipose tissue is linked to insulin resistance and metabolic diseases. Earlier studies have shown that hepatic lipid accumulation can occur after 4 d of a high-fat diet in humans, and this fat accumulation can be blunted by the ingestion of additional proteins.

Objectives: In this study, we explored whether a single high-fat meal increased the lipid content in liver and skeletal muscle as measured by using in vivo proton magnetic resonance spectroscopy (¹H-MRS) and whether the addition of protein can modulate the postprandial ectopic lipid storage.

Design: Intrahepatic lipid (IHL) and intramyocellular lipid (IMCL) concentrations were determined by using ¹H-MRS before and 3 and 5 h after a high-fat with added protein meal (61.5% of energy from fat) or a high-fat without added protein meal (mean ± SEM: 51.1 ± 7.9 g of protein; 191.9 ± 9.9 kcal added) in a randomized crossover study. IHL and IMCL concentrations were converted to absolute concentrations (g/kg wet weight) by using water as an internal reference.

Results: Nine lean, healthy subjects [6 men and 3 women; mean (±SD) age: 22.7 ± 3.0 y; mean body mass index (in kg/m²): 21.8 ± 1.8] were included in this study. IHL concentrations increased ∼20% (P < 0.01) at 3 h after the meal and did not further increase after 5 h. In contrast, IMCL concentrations were not altered during the postprandial period (P = 0.74). The addition of protein to a single high-fat meal did not change the postprandial accumulation of fat in the liver (P = 0.93) or skeletal muscle (P = 0.84).

Conclusions: In this study, we showed that a single energy-dense, high-fat meal induced net lipid accumulation in the liver, which was detected by using in vivo ¹H-MRS. This noninvasive approach might bring new opportunities to study postprandial hepatic lipid dynamics. The addition of protein did not change the ectopic lipid retention after a single high-fat meal.

Trial registration: ClinicalTrials.gov NCT01709643.

Keywords: 1H-MRS; IHL; IMCL; postprandial; protein.