In general, you can't trust self-reported data, especially not data reported to social acquaintances. Not only do people underreport how much they eat (it's th

In general, you can't trust self-reported data, especially not data reported to social acquaintances. Not only do people underreport how much they eat (it's the norm, even for people who aren't overweight), they don't do a good job of measuring their weight and reporting weight loss or weight gain. People really do say and believe that they've gained five pounds in two days, or lost ten pounds in a week, when it's clear they are just measuring fluctuations that have nothing to do with muscle or body fat.