This is what would happen during times of economic austerity or illness when rapid weight loss would potentially occur with little food consumed or available. (thehealthyhomeeconomist.com)
Some people eat very little foods yet continue to add weight. (abmachinesguide.com)
Those things include common mistakes like eating too little food (too few calories), eating too little protein, and exercising too much (especially doing too much cardio). (legionathletics.com)