Progressive caloric restriction induces dose-dependent changes in myocardial triglyceride content and diastolic function in healthy men

Context: In animal experiments, high plasma concentrations of free fatty acids (FFAs) are associated with increased triglyceride (TG) stores in liver and heart, and impaired cardiac function. In humans caloric restriction increases plasma FFA levels. Objective: Our objective was to assess the effects of progressive caloric restriction on myocardial and hepatic TG content and myocardial function. Design: This was a prospective intervention study. Participants: This study included 10 lean healthy men. Interventions: Three-day partial (471 kcal/d) and complete starvation was performed. Outcome Measures: Plasma levels of FFA, myocardial and hepatic TG content, and myocardial function were calculated. Results: Plasma FFA increased from 0.6 ± 0.4 mmol/liter to 1.2 ± 0.4 and to 1.9 ± 0.7 mmol/liter, after partial and complete starvation, respectively (P < 0.001). Myocardial TG content increased from 0.35 ± 0.14% to 0.59 ± 0.27%, and 1.26 ± 0.49%, respectively (P < 0.01). The ratio between the early diastole and atrial contraction decreased from 2.2 ± 0.4 to 2.1 ± 0.4 (P = 0.7) and 1.8 ± 0.4, respectively (P < 0.01), and diastolic early deceleration from 3.4 ± 0.7 ml/sec² × 10^-3 to 2.9 ± 0.5 and 2.8 ± 0.9 ml/sec² × 10 ^-3, respectively (P < 0.05). Hepatic TG content decreased after partial starvation (from 2.23 ± 2.24% to 1.43 ± 1.33%; P < 0.05) but did not change upon complete starvation. Conclusions: Progressive caloric restriction induces a dose-dependent increase in myocardial TG content and a dose-dependent decrease in diastolic function in lean healthy men. Hepatic TG content showed a differential response to progressive caloric restriction, indicating that redistribution of endogenous TG stores is tissue specific.