Chickweed is the herb most often thought of for metabolizing and burning fat. It also serves as an appetite depressant. It is wonderful in salads. Tinctures are preferable to the dried leaf. Regulators such as kelp are extremely important because they are so good for the glands.
Diuretics can be important when the weight appears as edema or water gain.
Dandelion, nettle, and fennel are good additions to a daily tea. I was interested to see gotu kola as the first herb on Chrystal Star's Appe-tight capsules. It is often cited as an appetite depressant, which is in addition to its use as a brain tonic. She also recommends stevia as a sweetener. I use stevia quite a lot, particularly in baking, and it has the additional advantage of being a blood sugar regulator.