-----"Each week, participants would come to the lab to eat dinner."

I take that to mean they were eating in a large group (control 26, to-go 27).

Eating in large groups increases food consumption.

Here is the research:

"Adults and animals consume more food when eating in the presence of others than when eating alone.1 This phenomenon, termed social facilitation, is defined as an increase in a behaviour merely from the sight or sound of others engaged in the same behaviour.2,3,4,5 Eating behaviour is one of the clearest demonstrations of the social facilitation effect, and has been documented in animals6,7,8,9,10 and adult humans 11,12,13,14,15,16,17,18,19,20,21,22; adults eat 30–50% more in groups than when alone.23 Prior human research has been limited by the fact that most studies measured amount consumed only by self‐report,11,12,13,14,15,16,17,18,19,21 and the group‐eating situations were not always comparable to the non‐group situations with regard to environment or meal content.16,24 To our knowledge, social facilitation of eating behaviour has not been investigated in children, nor has it been examined through direct observation or measurement of consumption in a natural setting.

Source: Archives of Disease in Childhood, May 2007,

The doggy bag options is good, but so is awareness of how many people you are dining with. It impacts your intake.