 [ Symptoms ] how can i eat so much be completely inactive and still lose weight  i eat more than anyone in my family and due to my back problems i am completely inactive like no exercise whatsoever but everytime i seem to weigh myself ive lost more weight im 20 years old and i still cannot even get to 100lbs is there something wrong with my metabolism [ Disease ] t his article on webmd explains the science and that yes websites and blogs tend to focus on the diet soda and weight gain and weight gain angle even though the evidence is scant studies show that when used with a reduced calorie diet non caloric drinks help people lose weight there is some concern that regular diet soda consumption increases the risk for heart disease and stroke but more studies are needed to confirm a relationship if you find it works for you then that is all that counts just keep an eye out for research on the health effects good luck