A team of researchers led by a group from the University of Illinois at Urbana-Champaign recently asked 3,622 young men and women in Mexico to estimate their body size based on categories ranging from very underweight to obese. People in the normal weight range selected the correct category about 80 percent of the time, but 58 percent of overweight students incorrectly described themselves as normal weight. Among the obese, 75 percent placed themselves in the overweight category, and only 10 percent accurately described their body size. (Notably, a sizable minority who were at a healthy weight described themselves as being underweight.)
Other studies have found the same thing. The more overweight someone is, the less likely they are to describe their own weight accurately.
From another study, These findings support the hypothesis that inaccuracies in self-reported weight reflect deliberate misreporting rather than a cognitive or perceptual bias. In other words, people are lying, as opposed to having a bias.
I am sure that most of us have met people who were hardly recognizable from the photo, which must have been from many years ago. Using an old photo is a different kind of dishonesty.
As Reagan said, trust but verify.