Moderate dietary weight loss reduces myocardial steatosis in obese and overweight women.

Background: Excessive myocardial triglyceride (MTG) content in obesity and type 2 diabetes is associated with impaired cardiac function. Previous studies suggest that MTG could be mobilized through lifestyle interventions. We assessed influences of moderate dietary weight loss in non diabetic obese and overweight women on MTG content and cardiac function.

Methods: We selected a subgroup of 38 women from the B-SMART study population. The B-SMART study compared weight loss and associated metabolic and cardiovascular markers with reduced-carbohydrate and reduced-fat hypocaloric diets. Selected subjects had completed a cardiac magnetic resonance (MR) scan including imaging and proton spectroscopy to assess cardiac structure and function as well as MTG content.

Results: An average weight reduction of 5.4 ± 4.3 kg at six months was associated with a relative decrease of MTG of 25% (from 0.72 ± 0.29% at baseline to 0.54 ± 0.23% at follow-up, p<0.001). The response was similar with carbohydrate and fat restriction. Diastolic function expressed as ratio of peak filling rate in E- and A-Phase (PFRE/PFRA) was unchanged. Reductions of left atrial size (from 21.9 ± 4.0 cm(2) to 20.0 ± 3.7 cm(2), p=0.002), the normalized ratio of PFRE and early diastolic lengthening velocity PLV (from 8.2 ± 2.6 to 7.5 ± 2.5, p<0.001) and fat free mass (from 55.1 ± 6.9 kg to 52.7 ± 6.5 kg, p=0.007) reflected altered cardiac volume loading after diet, but did not correlate to MTG content.

Conclusions: Moderate dietary weight loss significantly reduced MTG content in women with uncomplicated overweight or obesity. Macronutrient composition of the diet did not significantly affect the extent of MTG reduction.