Some herbs act on digestion, metabolism, or appetite to impact weight loss. Certain substances can increase thermogenesis, or metabolism, which may lead to weight loss.

Certain thermogenic, or stimulant, herbs have a reputation for aiding weight loss, but according to the FDA should be avoided due to serious or possibly fatal side effects. Weight loss herbs to avoid include: ephedra (or products containing ephedra), which can have dangerous cardiac side effects, herbal laxatives such as cascara sagrada or senna, which can cause serious intestinal problems.

Taking soluble fiber supplements adds bulk and makes one feel full, but without any added calories. It is imperative to drink adequate water when using fiber supplements to avoid constipation and digestive problems, and fiber supplements should be taken under supervision of a health care professional. Foods high in soluble fiber include apples, oatmeal, beans, and pears.