You must take on an empty stomach and no food for about an hour. Also, you need to keep the Synthroid level constant in your blood system. If you skip a day or two It is like you have to start over to get back to the dosage you were prescribed. This drug works. Use it as your Dr. tells you to and have blood tests on a regular basis. The amount of synthroid that you ingest on a daily basis can affect how much weight you’re likely to lose. The dosage is determined based upon the severity of an individual’s hypothyroidism, as well as his/her body mass index. In any regard, those taking higher doses of synthroid are likely to lose more weight than those taking extremely low doses. This has to be taken into account when you realize that you are finding it difficult to lose weight with hypothyroid medications like Synthroid. By treating the diabetes and controlling the blood sugar levels with mediation, exercise, and diet you can make the weight loss more effective. Synthroid should never be used to help you lose weight. Normal doses of Synthroid, which will keep your levothyroxine levels in your body within the normal range, will not cause you to lose any weight. If you can't tolerate the proper dose of Levothyroxine or Synthroid then you won't lose weight with the medication. And lastly, patients who don't have any other chronic medical conditions are more likely to do well on T4 only medications. If you are going to lose weight when you add Synthroid or levothyroxine it will only be a small amount IF the medication is right for you. What's more is that due to other mechanics in your body, the addition of T4 only medications like Synthroid and levothyroxine can actually lead to weight GAIN. Levothyroxine is a synthetic thyroid hormone prescribed to treat low thyroid function, also known as hypothyroidism. Low thyroid function slows down the metabolism and this can lead to weight gain. If you have normal thyroid function and are overweight, calorie reduction can help you lose excess body weight. A calorie deficit of 500 to 1,000 calories per day can help you achieve a weight loss of 1 to 2 lb. per week -- the amount recommended by the American Dietetic Association for the first 6 months of your weight-loss program. In fact, taking Synthroid to speed up metabolism and lose weight if you don’t have hypothyroidism can cause hormonal imbalance and induce negative health complications. The best thing to do to lose weight is to exercise and adjust your diet.