Did you read the article? In direct response to 1: "The researchers had already discovered that each session of intellectual work requires only three calories m

Did you read the article? In direct response to 1: "The researchers had already discovered that each session of intellectual work requires only three calories more than the rest period." So, yes, it does, but apparently the change in appetite more than offsets the increased consumption. And as for 2, this complaint is a pet peeve of mine. Yes, bigger sample sizes are (often) better, but sometimes you can't get a bigger sample. Size of sample and representativeness are kind of orthogonal, if all humans were homogeneous, sample sizes of one would be totally sufficient. (Basically, sure, there could be uncorrected bias, but please point to a bias that you think is unaccounted for, and not just "should have paid for more subjects".) Honestly, it kind of sounds like you want the study results to be something since you have preconceived expectations that thinking hard should use more energy. I'm not trying to be combative here, but I don't really know of anything wrong with their methodology. I haven't read the paper in question, but presumably neither have you, so we're two people on the internet arguing about something we haven't even read. Whoo, yay internet!