A holiday study split people into two groups: one never weighed themselves, the other weighed daily. The non-weighing group gained weight. The daily-weighing group lost weight. No diet or exercise changes. Just measuring the number shifted behavior.
There was a study done and it had a group of people during the holiday season. And what they did is they had one group of people who didn't weigh themselves and they had another group of people who weighed themselves every day. The group that didn't weigh themselves, they actually gained weight during the holidays. What happened to the group that did weigh themselves? They lost weight during the holidays. These people did not go on a diet, they didn't go on a meal plan, they didn't work out, they didn't change nothing. They were just conscious of their weight. If you simply measure something, it almost always goes in the direction you want it to.