Overall it's heartwarming to see how invested the trainers are in the contestants and how much they want them to succeed.
This also goes for host Alison Sweeney, who seems to light up every time a contestant loses a lot of weight on the scale.
In season nineone of the contestants, Stephanie, had a big number on the scale and cheerfully declared she wanted to hug Sweeney, to which Sweeney replied "You come over here and hug me!". A few episodes later Stephanie pulled another big number that brought her out of the 200s and Sweeney walked up and hugged her, whispering "That's awesome" to her. She's hugged several other contestants over the years as well.
The contestants themselves usually seem very happy and excited for one another when someone pulls a big number, regardless of which team they are on. For most of them it's clearly about weightloss and lifestyle change rather than gameplay.
O'Neal of season nine was this trope personified. Enormeously proud of his daughter Sunshine, said he felt like a surrogate father for Vicky on the ranch since she got a second chance later in the game just like himself and Sunshine, and earned the nickname "Unc" from Sam and Koli who saw him as a surrogate uncle.
Season ten had a challenge in which the prize was a car. Ada and a male contestant whose name escapes me were in a clear lead all through the challenge but then both stopped and waited for the one in third place, Patrick, to catch up to them so that he could win. Simply because they felt he needed the car as an unemployed father with two young children, and they didn't.