Are metabolically healthy obese patients also hemorheologically healthy?

We examined whether "metabolically healthy obesity" (MHO) is associated or not with hemorheologic alterations. We studied 110 subjects: 32 normal weight; 40 overweight; 38 obese. Overweight and obese subjects were divided into two subgroups according to the occurrence or not of a metabolic syndrome (METS). Subjects were thus categorized as follows: (1) metabolically healthy and normal weight (MHNW); (2) metabolically healthy but overweight (MHOW); (3) metabolically abnormally overweight (MAOW); (4) metabolically healthy but obese (MHOB); and (5) metabolically abnormally obese (MAOB). Across those various subgroups whole blood viscosity and plasma viscosity were not statistically different, although there was a tendency to higher values in the subgroups with METS compared to those without METS. RBC aggregation "M" was higher in all obese than MHNW (7.25 ± 0.64 vs 4.31 ± 0.44 p <  0.001 and was also higher in MHOB than MHNW (8.22 ± 1.07 vs 4.31 ± 0.44 vs 8.22 ± 1.07 p <  0.02). It was higher in all obese subjects than in all overweight subjects (7.25 ± 0.64 vs 5.22 ± 0.40 p <  0.01) but the difference between overweight and MHNW was not significant. M was negatively correlated with insulin sensitivity (r =-0.457 p = 0.0008). On the whole increased RBC aggregability "M" seems to be more related to fatness by its own than to the occurrence of metabolic abnormalities. MHO is not associated with alterations of blood viscosity at high shear rate, but exhibits a slight increase in RBC aggregability. These data are consistent with the assumption that MHO is on the whole a "hemorheologically healthy" situation, but that RBC aggregability is proportional to fatness even in "healthy" conditions, as already observed in samples of normal weight athletes.