Fatpacking is body composition change. Do not come fixated on one number -- weight. Your body is comprised of fat, muscle, water and bone. You may lose fat and gain muscle and water.
You may lose fat (yay!) but put on almost as much muscle and water for a small net loss of weight. People are crushed by losing only 1 pound, even though they may have lost fat, built muscle and took an inch or two off their waist. You still lost weight, but maybe not as much as you hoped.
While weight is not meaningless, it's sometimes misleading. If you drink say, a liter of water you gain 2 pounds. But should the extra 2 pounds really concern you?
Fatpacking is engaged in an ongoing study to determine a causality between backpacking and body composition change. Fatpacking's observed results can be perused by filling out the query form below.
You can use these results to get an idea of how much you might reasonably expect to alter your body composition. There is of course a lot of unaccounted for variability introduced from things like pack weight, trip length, contour and temperature, amount eaten, medications such as thyroid, and water retention for women.
We do not track BMI as it can be a grossly misleading measurement, especially for the muscular individuals we hope to become (however, we can provide BMI to participants who request it.)