# A Critical Review on Obesity: Herbal Approach, Bioactive Compounds, and Their Mechanism
## 5 Plant-Based Perspective  
Plant-based diets have lower all-cause mortality and a lower risk of obesity, type 2 diabetes, and coronary heart disease [139]. Plants have been used as traditional and natural pharmacological remedies from time immemorial. Phytomedicines are effective alternatives to synthetic pharmaceuticals in today's pharmacological assistance. Plant-derived secondary metabolites that have pharmacological or toxicological effects on humans and an  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Herb** & **Dose** & **Duration** & **Outcome** & **References** \\ \hline \multirow{4}{*}{_Ilex paraquariensis_} & \multirow{4}{*}{3150 mg/day} & \multirow{4}{*}{12 weeks} & \multicolumn{3}{c}{Decreased body fat mass, percent body fat, and} \\  & & & & waist-to-hip ratio \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\  
imals but play little or no role in plant growth and development are called phytomolecules. A wide range of plant products, including crude extracts and isolated pure natural components, can counteract diet-induced obesity and cause weight loss [140]. Obesity's rising danger to world health has prompted scientists and researchers to invest more effort into developing an effective anti-obesity component. Numerous natural-source promising materials, as well as their active constituents, have been explored. Most of these natural elements are produced from plants, such as fruits, vegetables, cereals, and herbs. The presence of an abundance of phytochemicals, fiber, and unsaturated fatty acids contributes to the biological advantages of these natural components.  
The anti-obesity products in the market can be classified into three categories: (1) food ingredients, (2) herbal ingredients, and (3) other functional supplements. The most popular section of the functional supplement market is arguably the development of functional items from what people usually eat in their everyday lives. Products derived from fruits (citrus and berries), grains (soybean), vegetables, or drinking liquids (tea leaves) are considered safer and more acceptable by customers. To treat patients with obesity, traditional Chinese medical practitioners utilize herbal medicines that are generally mixtures of several herbs, such as turmeric (_Curcuma longa_) and mulberry leaf (_Morus alba_). Herbal remedies have recently been popular not just in Asia but also in the Western world. That is why herbal materials might be a significant category of anti-obesity therapies. Other substances, such as probiotics and calcium supplements, have also shown anti-obesity properties. Citrus fruits are one of the essential categories for developing and commercializing novel anti-obesity therapies. Phytochemicals such as triterpenoids, flavonoids, and alkaloids have been plentiful in citrus fruits' peel and pulp. Citrus fruit extracts have anti-obesity properties in cell and animal experiments, helping to reduce body weight increase and white adipose tissue weight [141]. Leptin, a crucial hormone generated by adipocytes that regulates food intake and energy expenditure, was lowered by citrus fruit consumption. This alteration in hormonal activity is desired for creating an anti-obesity treatment based on citrus. The main bioactive flavonoid components in citrus fruits that might affect plasma leptin levels are metabolized flavones and flavanone glycosides. Green tea (_Camelia sinensis_)-derived anti-obesity products are also popular in the functional food sector. Polyphenols, which comprise flavonoids, flavones, and flavan-3-ols, are the most abundant bioactive compounds in green tea, accounting for up to 35% of the dry weight. Clinical investigations have shown that catechins (270 to 1200 mg/day) have positive benefits, such as reduced body weight, lower blood leptin levels, and reduced fatty acid absorption. Caffeine, another bioactive component of tea leaves, modulates somatic nervous system activity and works synergistically with catechins to promote energy expenditure and fat burning [142].