Wagyu beef is fatty, but there is something special about this meat. The ratio of monounsaturated to saturated fat is much higher in Wagyu than any other beef. Monounsaturated fat could have positive effects on heart health. The serving sizes of the Wagyu dishes are very small, so if you like a big steak it is probably better to go with lean eye fillet and not Wagyu.
An interesting study on the impact of the beef steak thermal processing on degradation of good fats and levels of inflammation after the consumption of the cooked beef. Pan-fried (PF) and sous-vide (SV) thermally processed beef were compared by measuring fifteen oxidised lipids in post-meal plasma. ‘Postprandial plasma inflammatory markers tended to remain lower following the SV meal than the PF meal.’ (Food Chemistry, Volume 184, 1 October 2015, Pages 57-64)