High-fat meals do not affect thrombin formation and fibrin clot lysis in individuals with obesity during intentional weight loss

Abstract Repeated weight loss cycles are associated with increased cardiovascular morbidity. Meal-induced thrombin formation, measured as prothrombin fragment 1+2 (F1+2), is observed in individuals with overweight after weight loss, and postprandial effects can be one of the mechanisms underlying harmful effects during intentional weight loss. We hypothesize that consumption of high-fat meals during intentional weight loss triggers a prothrombotic state by increasing postprandial F1+2 or decreasing fibrin clot lysis in individuals with obesity, and that the response associates with the gut bacteria composition. A cross-over meal study was conducted in patients admitted to bariatric surgery during dietary weight loss (N=20) and surgical weight loss (N=16) (weight loss groups). High-fat (67 E%) and low-fat (16 E%) meals were served at 08:15 and 10:00 on two study days. Blood samples collected at 08:00 (fasting), 12:00, and 14:00 were analyzed for triglycerides, activated factor VII (FVIIa), F1+2, D-dimer, fibrinogen, tissue factor (TF), and fibrin clot lysis. The proportion of gram-negative bacteria and bacterial diversity were analyzed in fecal samples obtained less than 24 hours before the meal test. Triglycerides and FVIIa increased after high-fat meals in both weight loss groups, whereas D-dimer (dietary group) and F1+2 decreased and TF and fibrin clot lysis did not change. There was a negative association between the proportion of gram-negative bacteria and changes in FVIIa in the surgery group. Postprandial FVII activation after high-fat meals is not accompanied by increased F1+2, irrespective of the weight loss intervention, but might be associated with the proportion of gram-negative gut bacteria.