Have you checked out your thyroid lately? The thyroid gland is tiny but plays a huge role in regulation the metabolism. Sometimes people who simply can not lose weight no matter what they try are simply not metabolizing food correctly because their thyroid is out of balance. A body needs to burn the calories it takes in to lose weight effectively. But if the regulator is not regulating, then nothing is getting burned off the right way.
To get your thyroid checked, go to a doctor and ask to have the full panel of tests done. This included the T4 test, which doctors sometimes do not do. This is the test that will indicate if your thyroid is functionally out of whack. If you do get diagnosed with low thyroid there are several things that you can do to take control of this problem. There is medication available and you can get onto a good thyroid diet plan to eat the foods that support the thyroid. A thyroid diet is good to incorporate even if you are on medication, to keep ahead of the metabolism curve and let your activity help you rather than exhaust you.