Metabolism, Weight Loss and Digestion

I had the gastric by-pass about two years ago and I found out that now my metabolism seems to have slowed now again; Are there some herbs I can take to raise my metabolism and also to lose weight?

You need to determine why your metabolism has slowed down. In most cases it is due to too much stress which affects the thyroid, as well as nutritional deficiencies. Considering the surgery you had, both are likely.
For information on herbs for a subclinical or under functioning thyroid and metabolism, please see: www.richters.com/qa-search.cgi?search=hypothyroid
To improve digestive function there are several thing you can do to turn on the digestive system: 1/ bitters herbs taken 10 to 30 minutes before meals - dandelion root, gentian root, valerian root, yellow dock root 2/ apple cider vinegar can be taken at the start of meals to help reduce the pH in the stomach - 1/4 to 1 tsp 3/ carminative herbs after the meal to help to stimulate good digestive secretions - dill seed, fennel, anise seed, chamomile, peppermint and leon balm are a few examples