Jatharagni, located in the duodenum, that is responsible for eliminating impurities in the food we eat and maintaining good health in the body. Surprisingly, this seems to loose its potency the moment someone is married or settled into a good job. This can be seen in the sudden increase in weight when people get married and/or get settled in a good job.
Jatharagni itself is the physical manifestation of the fire which is deeper inside. For most people, this fire is almost but extinguished by a marriage or a good job - leading to accumulation of impurities (obesity and ego). If one can hold on to the deeper fire (by aiming at something trans-egoic that one finds meaningful), then impurities can be eliminated from the system - neither body mass nor mental mass (ego) will accumulate!