The possible reasons for the foul smell of urine are as follows: First, a heavier smell can occur when the urine is in a concentrated state, such as when you drink less water and the urine is concentrated or when you sweat more and lose too much body fluid. At this time, the smell is heavier and accompanied by yellowish color, no urinary tract irritation symptoms, no urinary frequency, urinary urgency, painful urination. Second, when the diet contains more protein substances, it can cause excessive protein decomposition and produce nitrogen-containing substances. Bacteria in the urine decompose nitrogen into ammoniacal substances, which can produce a more testy smell. At this time, you need to adjust the diet structure and reduce the diet of meat and vegetables. Third, if urine is left in the bladder for too long, more ammonia in the urine decomposes and volatilizes, and a more testy smell of urine can occur. Fourth, if the diet contains special smelling foods, such as onion and garlic, it can cause a heavier urine odor.