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

Abstract

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. 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. 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. 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). 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.