Effect of Caloric Restriction and Dietary Composition on Liver Triglyceride Content in Subjects with Abdominal Obesity: the Wageningen Belly Fat Study
Authors: Mensink Marco , Schutte Sophie , Chatindiara Idah , Esser Diederik , Siebelink Els , Afman Lydia 
Published: November 2023

Intrahepatic lipid (IHL) accumulation is considered the hepatic manifestation of the metabolic syndrome. Obesity, in particular abdominal obesity, is associated with increased hepatic lipid accumulation. Lifestyle factors, like diet and physical activity play an important role in IHL accumulation. Caloric restriction (CR) results in lower IHL levels [Petersen et al., Diabetes 2005, 54:603–60] and several nutrients can be linked to hepatic lipid accumulation [de Wit et al, J Hepatol 2012, 57:1370–1373]. In the Wageningen Belly Fat Study our objective was to compare the effects of two different caloric‐restricted diets that differ in nutrient quality on IHL content.

The Belly Fat Study is a parallel, randomized intervention study of 12 weeks. 110 healthy overweight males and females aged 40–70 with abdominal obesity were randomly assigned to either one of two dietary advice intervention groups or a control group (CON, n=30). Dietary advice in the interventions was provided in two variants; a Western‐type caloric restricted diet (− 30en%, CR‐WD, n=40) and a targeted caloric restricted diet (−30en%, CR‐TD, n=40) that specifically aimed to improve organ health and to reduce lipid accumulation in the liver. The targeted diet was enriched in monounsaturated as well as polyunsaturated fatty acids including n‐3 fatty acids; contained an increased proportion of complex carbohydrates, whilst fructose being low; and had an increased soy protein content. Dietary advice was given on a weekly basis by skilled dieticians, and key food products were provided. The control group did not receive any dietary advice and were instructed to maintain their habitual diet. IHL content was measured by image‐guided single‐voxel spectroscopy, a quantitative version of 1H‐magnetic resonance spectroscopy. Measurements were performed on a 3.0T magnetic resonance scanner before and after intervention.

Change in IHL was evaluated in 80 subjects (19 CON, 33 CR‐WD, 28 CR‐TD). Average weight change was +0.5 ± 0.7 kg in CON, −6.4 ± 0.6 kg in CR‐WD, and −8.5 ± 0.6 kg in CR‐TD group. Weight‐loss in both CR diets was significantly different from CON, and a bigger weight loss was seen in the targeted diet group compared to the western diet group (p=0.016). Before intervention no difference in IHL was seen between groups (p=0.27). After 12 weeks, IHL was slightly increased in the control group, while strongly decreased in the CR groups (CON: 5.0 [3.7–6.7] % of H2O resonance; CR‐WD: 2.4 [1.9–3.1]%; CR‐TD: 1.9 [1.5–2.4]%, baseline IHL‐adjusted geometric means [95%CI]). Both CR groups were significantly lower than the control group (p<0.001, ANCOVA), while no difference was seen between the two caloric restricted groups (p=0.39, ANCOVA). The change in IHL was strongly correlated to the change in bodyweight (R=0.584, p< 0.001).

In conclusion, body weight loss through caloric restriction did strongly reduce intrahepatic lipid accumulation. There was no clear additional advantage of an improved nutrient quality on weight‐loss induced improvement in IHL.