I think to drink enough water or liquid is necessary for attaining a healthy weight. I also had a strict exercise routine including running and gym. My diet was also accurate as I consulted licensed nutritionist for my diet. But I was not losing weight. It was a serious problem for me, as I did not know the root cause of it. I also tested my blood, but everything was fine. As I consulted one expert, instead of asking deep questions on my diet and exercise plan, he asked questions related to my job, work and sleep pattern. He did not pretend that it was wrong, but he advised me a new plan with some variations, that were daily meditation, increase in daily sleep and less food at night. Practicing such a plan helped lose weight.