Natural Dietary and Medicinal Plants with Anti-Obesity Therapeutics Activities for Treatment and Prevention of Obesity during Lock Down and in Post-COVID-19 Era

Abstract

Overweight and obesity have become global epidemics, especially during the lockdown due to the COVID-19 pandemic. The potential of medicinal plants as a better and safe option in treating obesity and overweight has gained attention in recent years. Obesity and overweight has become a major public health concern, and its incidence rising at an alarming rate. Obesity is one of the major types of metabolic syndrome, resulting in various types of problems such as hypertension, diabetes, dyslipidemia, and excess fat accumulation. The current searching was done by the keywords in main indexing systems including Scopus, PubMed/MEDLINE, the search engine of Google Scholar, and Institute for Scientific Web of Science. The keywords were traditional medicine, health benefits, pharmaceutical science, pomegranate, punicalin, punicalagin, and ellagitannins. Google Scholar was searched manually for possible missing manuscripts, and there was no language restriction in the search. This review was carried out to highlight the importance of medicinal plants which are common in traditional medicinal sciences of different countries, especially Asia to prevent and treatment of obesity and overweight during the global pandemic and the post-COVID-19 era.

1. Introduction

Traditional medicine is used not only for treatment but also for prevention [1,2,3,4,5,6], which is as old as mankind itself [7]. Medicinal plants which have been used in traditional medicinal science have relatively minimum or no negative impacts and toxicity, and their applications have been increased because of accessibility, affordability, easy availability, and acceptable efficacy [8,9,10]. Obesity is the main and primary reason of various metabolic ailments according to the epidemiological evidence, such as hypertension, diabetes, cardiovascular complications [11,12], asthma, arthritis, non-alcoholic fatty liver, degenerative disease, etc. [13]. Obesity is a serious health issue causing numerous health impairments, such as musculoskeletal disorders, cardiovascular diseases, type-2 diabetes, and different types of cancer [14]. Vulnerability to COVID-19 increases due to obesity, because both diseases share common inflammatory/metabolic pathways [15]. Notable changes in diet, sleep, physical activity, and mental health were reported by participants during the lockdown [16]. The Centers for Disease Control and Prevention list severe obesity (body mass index of ≥40 kg/m²) as a risk parameter for severe illness from COVID-19 [17]. During the pandemic, promotion of physical activity and prevention of obesity are as important as physical isolation of severely obese individuals [18]. Physical activity, maternal prenatal diet, psychological stress, sleep quality, and oxidative stress promoting disease conditions are important modulators of obesity and oxidative stress [19,20]. Obesity in individuals with COVID-19 independently has a relationship with increased risk for ICU admission and intubation [21,22]. Fat accumulation is caused by low levels of daily exercise and excessive food intake, which may influence fatty acid synthesis and betaoxidation. A linear dose–response link between body mass index and COVID-19 severity and mortality has been suggested, and obesity (body mass index ≥ 30 kg/m²) may cause a significantly increase in risk of critical COVID-19 and in-hospital mortality of COVID-19 [23,24]. Natural sources provide an advantageous basis for development of novel anti-obesity products [25]. Food supplements and functional foods containing fruit extracts, vegetables, and herbal products are also gaining increased attention [26] as an important natural alternative to prevent metabolic syndrome and obesity [27,28]. This review article is aimed to introduce and survey the most important medicinal plants on the basis of different traditional medicinal sciences containing chemical constituents with anti-obesity activities for treatment and prevention of obesity and related disease during the pandemic, quarantine, and the post-COVID-19 era.

2. Materials and Methods

The manuscript covers review articles, randomized control experiments, analytical studies and observations, which have been gathered from different sources such as Google Scholar, Scopus, Science Direct and PubMed. A review of the literature was carried out using the keywords COVID-19, obesity, natural products, medicinal plants, overweight, body mass index, and global pandemic.

3. Obesity

It has been reported that nutritional management may have obvious effects on the risk for chronic and obesity diseases [29,30]. The measurement tool which is mainly used in the clinical studies to identify obesity and overweight is called body mass index (BMI), which classifies people as normal weight (18.5–24.9 kg/m²), overweight (25–29.9 kg/m²), and obese (≥30 kg/m²) [31,32,33]. Obesity affects mortality, morbidity, and quality of life [34]; moreover, both overweight and obesity have increased attention in different societies, especially in urbanized populations [35,36]. Obesity shows harmful impacts and is believed to contribute to the increasing cardiovascular mortality [37]. Being overweight or obese is a risk factor for various costly comorbidities, such as type 2 diabetes (T2D), sleep apnea, chronic pain, cardiovascular disease, and certain cancers [38,39]. The frequency of obesity and overweight among children is increasing in the European region [40] and Canada [41], and women are presently more likely than before to suffer from obesity problems [42]. Impaired glucose tolerance of obese children is believed to exhibiting emerging oxidative stress levels [43]; obesity of childhood is a big concern as it is a principal predictor of obesity in adulthood [44]. The link between the presence of risk factors for different diseases and obesity in childhood with the early development of those diseases has been proven [45]. Prevention as well as treatment of obesity is important for children [46]. Obesity is linked with consequences of pneumonia, a protective impact coined the obesity paradox [47]. Obesity rates have dramatically risen among patients needing rehabilitation following join arthroplasty, injury, stroke, or an acute medical event [48]. Obesity may increase the risk of cardiovascular disease [49], and it is a risk factor for asthma [50].Obesity influences female reproduction by disturbing the hormone metabolism, the follicular environment, and body metabolism [51]. There is also a connection between obesity and cognitive reactivity, as well as depression [52]. An important risk factor for obesity is sleep duration [53]. The relationship between periodontal risk indicators and obesity in adolescents which may lead to oral morbidity has been found [54]. The important symptoms of metabolically healthy or unhealthy parameters are waist circumference, low-grade inflammation, HDL cholesterol, blood pressure, and diabetes [55].

4. Obesity and COVID-19

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has spread quickly from Wuhan, China to all parts of the world. A significant increase rate of obesity was found during the era of the COVID-19 epidemic [56,57], and also among obese patients with obstructive sleep apnea (OSA), an increased prevalence of COVID-19 was reported [58]. COVID-19 may lead to economic shutdown, confinement, and direct impacts, and consequently obesity development and eventually increased susceptibility to COVID-19 [59,60,61]. The worse outcomes of obese patients with COVID-19 consist of need for mechanical ventilation which is the consequence of respiratory failure and increase number of mortalities [62]. Body mass index, weight, and overweight escalated among children during the COVID-19 lockdown, influencing disadvantaged subpopulations, and related methods are required to decrease the impacts of the COVID-19 lockdown on childhood obesity and unhealthy weight gain [63]. The higher body mass index (BMI) in COVID-19 patients was reported, which is an important parameter that should always be evaluated for treatment and management of COVID-19 patients [64]. Obesity significantly increases the risk for hospitalization, demanding intensive care unit (ICU) admission, needing invasive mechanical ventilation (IMV) support, and risk for death among patients with COVID-19 [65,66,67]. Reports from the USA and Europe revealed remarkable morbidity and mortality in obese individuals with COVID-19 [68]. Obesity may have a noticeable role in the high incidence of mortality in black and Hispanic populations [69]. Recognition of populations with high fatality in COVID-19 gives clear insight to manage the pandemic by health services [70]. A need for policies is suggested which may support healthy lifestyle behaviors among low-income children during the pandemic [71]. Obesity may contribute to the increased risk and poorer prognosis of COVID-19 [72]. Obesity has a relationship with an immune state favorable to a cytokine storm, and serum concentrations of tumor necrosis factor alpha (TNF-α) and interleukin (IL)-17A are more increased in patients with obesity and COVID-19, and finally, they have a greater possibility of developing acute respiratory distress syndrome (ARDS) and death [73]. Biopsychosocial parameters which may influence COVID-19 pandemic-related obesity in children are (a) biological parameters including acute stress effects, altered leptin and adiponectin, chronic inflammation, intestinal dysbiosis, dysregulated immunological response, and stress increased inflammation and immune response; (b) social parameters such as household size, food insecurity, increased caloric consumption, increased screen time, lower educational achievement, parental factors, social distancing, sedentary lifestyle, socioeconomic status, and unhealthy diet; (c) psychological parameters like boredom, anxiety, food attitudes, food behavior, irritability, lack of self-regulation, maternal mental health loneliness, sleep disorders, and mental distress [74]. Reduced antithrombin is connected to mortality in COVID-19, and it has a relationship with obesity in COVID-19 [75,76,77]. Obesity and type 2 diabetes may have a role in the severity of disease and even mortality [78]. Subjects with obesity influenced by COVID-19 need longer hospitalization and much more time to clear from COVID-19 shedding compared to patients without obesity [79]. Inappropriate immune response is generated by obesity-induced chronic inflammatory status [80]. Isolation and quarantine can induce anger, anxiety, depression, and stress which are associated with unhealthy lifestyle leading to obesity. Higher BMI is connected with lower diet quality and levels of physical activity and a greater reported frequency of overeating during the lockdown [81]. Obesity could alter severe COVID-19 disease to younger ages [82]. Higher body mass index (BMI) and obesity are the major leading comorbidities to boost the risk of COVID-19 severity [83,84]. Obesity (BMI > 30 kg/m²) was connected with a significantly increased risk of critical COVID-19 and mortality [85]. Excess body weight multipliesthe risk of serious events connected to COVID-19 by 5.6 [86]. Dose–response meta-analysis indicates an increase of 5% risk for poor outcomes for every 5 kg/mg² increase in body mass index [87]. There is a linear increase in risk of severe COVID-19 at a BMI of more than 23 kg/m², leading to admission to hospital and death, and also a linear increase in admission to an ICU across the whole BMI range was reported [88]. Obese patients needed longer hospital stay and more days of mechanical ventilation compared to non-obese patients [89].

5. Medicinal Plants and Obesity

The increasing risk of obesity is associated with unhealthy plant foods [90,91], and consumption of healthy plant foods may be appropriate to decrease inflammation factors like TGF-β and hs-CRP [92], and plants which may show great potency to prevent obesity may have significant potential to inhibit pancreatice lipase [93]. The negative relationship between water hardness in water purification plants and the percentage of obese people has been reported [94], while the effective intervention within a complex system approach to manage obesity may be formed by plant secondary metabolites [95]. Phytochemicals with anti-obesity impacts are phenolic acids (o-Coumaric acid, Caffeic acid, Chlorogenic acid), Curcuminoids (Curcumin), Lignans (Podophyllotoxin), Flavonols (Quercetin), Isoflavonoids (Genistein, Daidzein, Glycitein), Flavones (Apigenin, Luteolin, Tangeritin), Flavans-3-ol (Catechin), Phytosterols (Diosgenin, Brassicasterol, β-Sitosterol, Campesterol), Anthocyanins (Cyanidin, Delphinidin, Malvidin, Pelargonidin, Peonidin), and Alkaloids (Caffeine, Capsaicin) [96]. Wheat (Triticum aestivum) sprout (TAEE) meaningfully reduced serum total cholesterol (TC), body weight, and low-density lipoprotein cholesterol levels in highfatdiet (HFD)-fed mice, and decreased lipid accumulation in epididymal white adipose tissue (EWAT) and liver. TAEE-treated mice indicated significant reduction in peroxisome proliferator-activated receptor γ (PPARγ) and fatty acid synthase expression in EWAT, which proved its efficacy for therapy for obesity and related diseases [97]. It has been found that luteolin, which is a Chinese herb, may be putative Furin inhibitor with tremendous benefits against Dengue Fever, and application of Chinese herbals and ion channel inhibitors can restrict the endothelial penetration of SARS-CoV-2 [98]. Natural phenolic compounds can be beneficially applied as food or fortified foods to control obesity [99].

Wild edible species from Southern Italy such as Daucus carota L., followed by Bellis perennis L. and Asparagusofficinalis L. showed inhibitory activity on NO production and protein denaturation, and D. carota indicated the best lipase inhibitory potential, which represented them as the appropriate candidates and the potential therapeutic agents in the treatment of obesity and inflammatory disorders [100]. Rosmarinus officinalis and Prunus avium contain the highest amounts of gallic acid, quercetin, ferulic acid, and epigallocatechin gallate which can be utilized against obesity in Turkish folk medicine [101]. The impacts of gut microbiota on obesity have been discovered in most animal and some human trials, and certain strains of Bacteroidetes, Firmicutes, and Lactobacillus have anti-obesity activities [102]. Apple, berries, chili, grapes, turmeric, sorghum, soy, and barley show anti-obesity efficacy via improving the diversity of gut microbiota, down-regulating obesogenic gut microbiota, and up-regulating anti-obesity gut microbiota [102]. Plant-based bio-active and fiber-enriched diets help in the alleviation of obesity and related diseases [103]. The most famous traditional medicinal plants in India for treatment of diabetes mellitus ailments, and potent candidates and substitutes to synthetic drugs in obese models are Acalypha indica, Pergulari ademia, and Tinospora cardifolia [104]. Folk herbal medicines for obesity are Zingiber officinale Roscoe, Carica papaya L., Hibiscussabdariffa L., Bauhinia variegata L., Foeniculum vulgare Mill., Caralluma tuberculata N.E.BR., Prunus avium (L.), Citrus medica L., Senna alexandrina Mill., Rosmarinus officinalis L. [105,106], Fucus vesiculosus, and Citrus aurantium [107]. In South Africa, three medicinal plants, namely Curtisia dentate, Cissaempelos capensis, and Schotia latifolia were repeatedly highlighted by the traditional healers and the local dwellers to have weight-reducing properties [108]. In Brazil, some of the most important species with great effective anti-obesity properties are Annona muricata L. and Hancorniaspeciosa Gomes, Baccharis trimera (Less.) DC, Camellia sinensis (L.) Kuntze, and Hibiscus sabdariffa L., showing some beneficial activity against obesity [109]. A natural pigment that mainly exists in the mature fruit of tomatoes is called lycopene, which effectively contributes to protecting against obesity and diabetes in animal studies [110]. Wines and grape berries are reported as the principal sources of stilbenes in human nutrition, which can alleviate the adverse effect of obesity by regulating various pathways [111]. By-products of guava and acerola can be applied as a sustainable alternative in the treatment of obesity [112]. Rosmarinic acid prevents excessive lipid accumulation and inflammation in human adipocytes, which shows its great potency for treatment of obesity-related inflammation [113]. Garlic extract in combination with ginger can prevent obesity in rats, and improved antioxidant enzyme’s activity [114]. A bioactive compound in celery (Apium graveolens) is 3-N-butylphthalide (NBP), which blocks the inflammatory response and regulates fat browning in HFD-induced obese mice, which indicates its effectiveness in combating obesity and its related metabolic disorders [115]. Various natural agents have been discovered for their obesity treatment potential such as Garcinia cambogia, apple cider, green tea, Panax ginseng, chia seeds, etc. [116]. Withania somnifera Dunal presented blood glucose-lowering and diuretic impacts in humans, comparable to daonil [117]. Acia (Euterpe oleracea Mart.) fruit anthocyanins decreased high-fat diet-induced obesity and hepatic steatosis, and increased high-fat diet-induced insulin resistance [118]. One of the promising anti-obesity agents is coffee fruit and oneof the traditional Chinese medicines is Caffeic acid [119]. Berberine is found to have an effective influence on gene regulation for the absorption of cholesterol at a daily dose of 300 mg in humans [120]. A classic traditional Chinese herb medicine which is called Wu-Mei-Wan can prevent obesity and its underlying mechanisms through attenuating white adipose tissue and increasing brown adipose tissue function [121]. Isolated Tomatidine from the green fruits and leaves of some plants in the Solanaceae family may significantly suppress the expression of fatty acid synthase and transcription factors are involved in lipogenesis and improve the expression of adipose triglyceride lipase, promoting the sirtuin 1 (sirt1)/AMPK signaling pathway to boost lipolysis and β-oxidation in fatty liver cells [122]. Hibiscus (Hibiscus shizopetalous; Hibiscus subdariffa), Argel (Solenostemma argel), and Caralluma (Caralluma quadrangular; Caralluma tuberculata) are famous traditional medicinal plants, and Argel indicated the highest inhibitory activity against lipase, α-amylase, and α-glucosidase enzymes, and the strongest lipase inhibitory activity was reported for the pregnane glycoside, and stemmoside C [123]. Roselle (Hibiscus sabdariffa) showed adipogenesis, reduced oxidative stress and systemic inflammation, and increased obesity-induced insulin resistance and insulin sensitivity [124]. EGCG, kaempferol, and quercetin have shown significant potent capability of anti-obesity activities [125,126]. Grape seed flour (GSF) prevented diet-induced obesity in C57BL/6J mice [127]. Procyanidins are a group of flavonoids, showing anti-obesity effects and increased metabolic flexibility and energy expenditure [128]. Crataegus pubescens and Ocimum sanctum ameliorated obesity and hyperglycemia in obese rats, reduced adipocyte hypertrophy, and can be introduced as ingredients for the elaboration of functional beverages [129]. The saprophytic fungus belongs to the family polyporaceae, Poria cocos, and synthesized Poria cocos gold nanoparticles caused the distinctions of influential nanoparticles which proved its ability as the potent anti-obesity drug [130]. Hussein et al. [131] reported that green coffee bean aqueous extracts and Spirulina platensis reduced liver weight, the final body weight, and the serum levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphate, and they can be potentially considered as anti-obesity substances. Cercato et al. [132] also reported that the flavonoids quercetin, naringenin, genistein, epigallocatechin gallate, apigenin, and cyaniding 3-glucoside have potential in complementary therapy against obesity. Some of the most important plants, herbs, and fruits with anti-obesity characteristics are shown in

Table 1. Anti-obesity potential of some medicinal plants and fruits.

Plant	Plant Family	Key Point	References
Acosmium dasycarpum (Vog.) Yakovlev (Unha D/anta)	Fabaceae	It is a Brazilian medicinal plant known as “Unha D/anta”, especially found in the Cerrado (Brazilian Savanna) area.	[133]
		Ascomium dasycarpum promoted metabolic syndrome; its root bark clearly ameliorates triglycerides; it has beneficial impacts on adiposity and weight reduction.	[133]
Allium cepa L. (Onion)	Amaryllidaceae	Onion peel extract meaningfully reduced the lipids of 3T3-L1 cells and restricted lipid accumulation by decreasing the expression of lipogenesis-related genes, with impressive anti-obesity impacts.	[134]
Aloe barbadensis Miller (Aloe vera)	Asphodelaceae	Aloe vera gel application regulated adipose tissue accumulation in obese rats.	[135]
		Aloe vera gel regulated the dyslipidemia as well as oxidative stress in obese rats.	[135]
Amorphophallus konjac K. Koch (Konjac)	Araceae	It has positive impacts on prevention and treatment of obesity because of its components konjak and glucomannan.	[136]
Artemisia sphaerocephala Krasch (Artemisia)	Asteraceae	Its polysaccharide fractions prevent obesity.	[137,138]
Betula utilis (Himalayan birch)	Betulaceae	Betula utilis bark is rich in pentacyclic triterpenoids thus it can be considered for management of overweight and associated comorbidities.	[139]
Bupleuri Radix (Chaihu)	Apiaceae	Bupleuri Radix extract (BupE) increased HFD-induced lipid disorders through FGF21 signaling pathway.	[140]
		BupE reversed obesity-related changes in structure and function of gut microbial communities.	[140]
Butea monosperma (Sacred Tree)	Fabaceae	Its flower extract can normalize the weight gain parameters.	[141]
Caralluma fimbriata	Apocynaceae	Application with C. fimbriata extract while controlling overall dietary intake and physical activity may be useful in curbing central obesity, and the key component of metabolic syndrome.	[142]
Corchorus olitorius L. (Nalta jute)	Malvaceae	Molokhia leaf extract ameliorated guy dysbiosis and high-fat diet-induced obesity.	[143]
Cuminum cyminum L. (Cumin)	Apiaceae	It contains essential fatty acids, flavonoids, volatile oils, etc., and may have influence on weight and other anthropometric indices in obese and overweight people.	[144]
Carum carvi L. (Caraway)	Apiaceae	Cumin promoted anthropometric and metabolic indices in overweight and type 2 diabetic subjects.	[145,146]
		As a traditional medicine, it may attenuate body mass index, body fat percentage, and body weight loss.	[147]
Cyclopia spp. (Honeybush)	Fabaceae	It has been used as the herbal tea (honeybush), which shows anti-obesity effects, especially by targeting adipose tissue.	[148]
Cynara scolymus L. (Artichoke)	Asteraceae	Artichoke has tremendous potency as anti-obese agent.	[149]
Cynometra cauliflora Linn. (Nam-nam)	Fabaceae	It can be used for obesity management.	[150]
Cynomorium songaricum Rupr. (Suo Yang)	Cynomoriaceae	HCY2, a triterpenoid-enriched extract of Cynomorri Herba treat obesity via the regulation of AMPK/PGC1 pathways.	[151]
Echium angustifolium Mill.	Boraginaceae	It can be considered as the potent candidate for oxidative stress, diabetes, and obesity.	[152]
		OBE100 and OBE104 are natural Eu extracts which are rich in pentacyclic triterpenes, and can be used to combat obesity and diabetes, and treatment with OBE100 had better effects than OBE104.	[153]
Garcinia cambogia (Garcinia)	Clusiaceae	Garcinia cambogia and Glucomannan decrease weight, alter body composition, regulate lipid and glucose blood profiles in overweight/obese patients.	[154]
Gnidia glauca (Fres.) Gilg (Fish Posion Bush)	Thymelaeaceae	It may reduce the body weight, organ weights, anthropometric indices, organo-somatic indices, the total fat content, adiposity index, atherogenic index, and various lipid profiles.	[155]
Ganoderma lucidum sensu stricto (Mushroom of immortality)	Ganodermataceae	It has shown anti-obesity effects.	[155,156]
Hibiscus sabdariffa L. (Roselle)	Malvaceae	Cholesterol and triglycerides levels indicated non-significant reductions in animals treated with Hibiscus sabdariffa, with its anti-obesity effect.	[157]
Ilex paraguariensis (Yerba mate)	Aquifoliaceae	After treatment with Ilex paraguariensis, a drop in respiratory quotient (RQ) was observed, revealing a rise in the proportion of fat oxidized.	[158]
Justicia carnea Lindl. (The Brazilian plume flower)	Acanthaceae	The methanolic leaf extract of Justicia carnea is a rich natural source of antioxidant and anti-obesity agents which could be optimized for development of new anti-obesity drugs.	[159]
Juniperus communis L. (Common Juniper)	Cupressaceae	It is an indigenous plant with significant in vitro anti-obesity impacts in adipocytes differentiation.	[160]
Ligustrum robustum Blume	Oleaceae	In Chinese folk medicine, its leaves are used in the treatment of obesity and hyperlipidemia, and its anti-obesity impact was associated with up-regulation of leptin.	[161]
Lobelia chinensis lour (Asian lobelia)	Campanulaceae	Polysaccharide from Lobelia chinensis lour is an insulin-type fructan with Mw of 2.6 kDa that indicated the potential of anti-obesity effect in HFD-induced mice.	[162]
Macrotyloma uniflorum (Lam.) Verdc. (Horse gram)	Fabaceae	Macrotyloma uniflurom formulation may increase the activity of enzymatic superoxide dismutase, glutathione peroxidase, catalase, and non-enzymatic antioxidants and could be applied in treatment and prevention of fat-induced oxidative stress and inflammation.	[163]
Mangifera indica Linn. (Mango)	Anacardiaceae	Its anti-obesity activity may be mediated partially via pancreatic lipase inhibitory activity and partially through reduction in food intake and improvement of antioxidant status.	[164]
Melissa officinalis L. (Lemon balm)	Labiatae	The herbal extract ALS-L1023 may block visceral obesity, and also decreases the increased fasting blood glucose, impaired glucose tolerance, and pancreatic dysfunction seen in female obese mice.	[165]
Memecylon umbellatum Burm. f. (Ironwood)	Melastomataceae	The oral administration of methanolic extract in mice may decrease hyperglycemia, triglycerides, body weight, and ameliorates insulin resistance.	[166]
Moringa oleifera Lam. (Drumstick tree)	Moringaceae	Its extract up-regulated adiponectin gene expression in obese rats relative, and down-regulated mRNA expression of leptin and resistin.	[167]
		Traditionally, M. oleifera leaves considered as anti-obesity herbal medicine.	[168]
		Its oil extract is considered to have cholesterol-lowering properties and a potential to treat obesity, while lycopene is a potent antioxidant.	[169]
Moringa peregrine (Forssk.) Fiori.	Moringaceae	Its bark and leaf extracts revealed potential anti-obesity and hepatoprotective activity through reduced lipid absorption, anti-hyperlipidemic impacts, and hepatic antioxidant effects.	[170]
Morus alba L. (Common mulberry)	Moraceae	The inhibitory impacts of mulberry on digestive enzymes and adipocyte differentiation, and its stimulatory influences on energy expenditures, and lipid metabolism may have a role in obesity regulation.	[171]
Nigella sativa L. (Fennel flower)	Ranunculaceae	It shows a moderate impact on reduction in body mass index and body weight.	[172]
Oroxylum indicum (L.) Kurz (Kyaung shar)	Bignoniaceae	Oroxylin A, chrysin and baicalein were suppressed lipid accumulation in 3T3-L1 preadipocytes and PL enzyme.	[173]
		Oroxylin A and chrysin also suppressed PPARγ and C/EBPα, main adipogenic transcription factors, in 3T3L-1 preadipocytes during adipogenesis process at 50 μM dose.	[173]
Passiflora edulis Sims (Passion fruit)	Passifloraceae	Passiflora edulis peel flour could be considered as an adjuvant to control of early parameters in obesity dysfunction.	[174]
Pilosocereus gounellei (F.A.C. Weber) Byles and G.D. Rowley	Cactus	Its stem extract enhanced serum lipid profile of the animals, lessened atherogenic indices, liver steatosis, epididymal fat, and pro-inflammatory cytokines.	[175]
Piper nigrum L. (Black pepper)	Piperaceae	Piperine was separated from methanolic extract of Piper nigrum seeds, which may have suppressed role in body weight, increase insulin and leptin sensitivity, ultimately leading to balance obesity.	[176]
Populus balsamifera L. (Balsam poplar)	Salicaceae	It has been known as a culturally adapted therapeutic approach for the treatment and care of diabetes and obesity.	[177]
Psidium guajava L. (Common guava)	Myrtaceae	Guava leaves promoted the vascular dysfunction in obese mice, and its application may have a positive effect on metabolic functions in obese mice.	[178]
Salacia chinensis L. (Chinese salacia)	Celastraceae	It is generally regarded that Saptrangi and Salacia chinensis-loaded gold nanoparticles ameliorate body weight, adipose index, resistin, inflammatory markers and AMPKα1, liver marker enzymes, leptin, and lipid profile.	[179]
Salvia hispanica L. (Chia)	Lamiaceae	Chia oil increased glucose metabolism and it has revealed potential to protect against the development of obesity-related diseases.	[180]
Salvia officinalis L. (Common sage)	Lamiaceae	Common sage provides novel natural treatments for the relief or cure of obesity.	[181]
Smilax china L. (Baqia)	Smilaceae	Smilax china L. polyphenols may be applied as a potential candidate to prevent obesity.	[182]
Smilax glabra Roxb. (Glabrous greenbrier)	Smilaceae	Smilax glabra rhizome may change the anti-obesity constraints in high-fat diet and obese diabetes in animal models.	[183]
Solenostemma argel Hayne	Apocynaceae	Argel is a promising Egyptian natural substitute, as it is rich in pregnane glycosides.	[184]
TabebuiaavellanedaeLorentz ex Griseb	Bignoniaceae	The n-BuOH extract of Taheebo prohibited ovariectomy-induced obesity and reduce fat mass in ovariectomized mice.	[185]
Tinospora cordifolia (Thunb.) Miers.	Menispermaceae	It was discovered to be efficacious in regulating body weight in a high-fat diet (HFD)-fed rats by keeping energy metabolism and cellular homeostasis.	[186,187]
Urtica dioica L. (Common nettle)	Urticaceae	It may decrease diet-induced weight gain and insulin resistance.	[188]
Vaccinium arctostaphylos L. (Caucasian whortleberry)	Ericaceae	Vaccinium arctostaphylos berry may have antihypertensive influence, and significantly lowers systolic and diastolic blood pressures in overweight/obese hypertensive patients.	[189]
Withania somnifera (L.) Dunal (Winter cherry or poison gooseberry)	Solanaceae	Withaferin A (WFA) which is the principal component of Withania somnifera extract, restricted HFD-induced obesity, and regulated mitogen-activated protein kinase (MAPK) signaling and AMP-activated protein kinase (AMPK) in adipose tissue.	[190]

.

Two famous traditional Chinese medicines, namely Rheum palmatum L. (Chinese rhubarb) (Polygonaceae), and Prunella vulgaris L. (the common self-heal) (Labiatae) are rich sources of anti-lipase compounds which can be considered as natural sources for crude anti-obesity drugs [191]. Consumption of bitter almond gum may decrease body mass index and body weight, alleviate hyperinsulinemia in hyper lipidemic subjects, reduce serum triglycerides, and can be applied for the management of body weight in fruit juices [192]. Saponins are the best candidate as appetite suppressants and pancreatice lipase, and may manage fattlier liver formation and body weight [193]. Acacia arabica, Agrimonia eupatoria, Aegle marmelose, Allium sativum, Allium cepa, Azadirachta indica, Aloe vera, Beta vulgaris, Benincasa hispida, Caesalpinia bonducella, Coccinia indica, Citrullus colocynthis, Eucalyptus globules, Ficus bengalenesis, Gymnema sylvestre, Hibiscus rosasinesis, Ipomoea batatas, Jatropha curcus, Mangifera indica, Morus alba, Momordica charantia, Mucuna pruriens, Ocimum sanctum, Punica granatum, Pterocarpus marsupium, Syzigium cumini, Tinospora cordifolia, and Trigonella foenum graecum are the most notable plants with antidiabetic potential in Indian traditional medicine with anti-obesity characteristics [194]. Dietary fruit intake was positively associated with P53 and PTEN gene expression in visceral and subcutaneous adipose tissues (SAT) obese participants [195]. Dandelion (Taraxacum officinale (L.)) and luteolin may improve HDLcholesterol in obese rats fed a normal-fat diet [196]. The natural compound celastrol, a pentacyclic triterpene isolated from the roots of Tripterygium wilfordi (thunder god vine) plant shows different bioactivities including and antidiabetic and anti-obese impacts [197]. The impacts of taking the combination of Zataria multiflora Boiss. (Zm) and oxymel may reduce insulin resistance and hip and wasit circumferences in overweight patients [198]. Dietary ginger controls body weight gain by inducing browning of white adipose tissue (WAT) and remodeling whole-body energy metabolism [199]. Coleus forskohlii extract and Garcinia indica extract increase energy expenditure through promotion of fatty acid β-oxidation, and attenuating the Firmicutes/Bacteroidetes to attenuate obesity [200]. African walnuts reduced lipid accumulation in adipose and ectopic tissues in MSG-obese rats [201]. Red maple (Acer rubrum) leaves extract decreased diet-induced obesity without influencing energy intake, and its impacts are partially because of the modulation of gut flora [202]. Indian brown algae (Padina tetrastromatica) is the major component for obesity management [203]. Fagara tessmannii is a shrub of the African rainforests in the South-West, Center, South, and East provinces in Cameroon, regulating the loss of ectopic fat and other fatty tissues, the energy expenditure and the renovascular decompression, the sensitivity of the peripheric tissues to insulin, and promotes ion movement which prevents hypertension [204]. The ethanolic extracts of Actaea racemosa L. have been proven as the best candidate for treatment of obesity and related diseases for further studies [205]. Garcinia indica extract standardized for 20% Garcinol inhibited adipogenesisin vitro3T3-L1 cells, decreased endoplasmic reticulum stress in adipocytes, alleviated visceral fat weight, and regulated obesity by acting on the AMPK-ER stress axis [206]. Chrysin is a flavonoid found in plant extracts from Passiflora species, alleviated the body weight of rats, decreased calorie intake of rats, and the hypertrophy of adipocytes [207]. Application of licorice extract with a low-calorie diet can efficiently increase the lipid profile in overweight and obese subjects [208]. The anti-obesity activities of the essential oils of hedgenettles (Stachys inflata, S. lavandulifolia, and S. byzantina) have been reported [209]. Huang-Qi San (HQS), the traditional Chinese medicine, can ameliorate hyperlipidemia with obesity [210]. Meratrim formulation, yerba mate, spinach, brown beans, sorghum, psyllium, and rye showed evidence for suppressing appetite [211]. A combination of resistance training with 500 mL/g of glycyrrhizic acid supplement may be appropriate to decrease body weight and body fat percentage [212]. In Mexico, one of the common herbal products used for weightloss is based on soybean, green tea, and aceitilla [213]. Methylxanthines are nutraceuticals mainly present in tea, coffee, and chocolate, and the most well-known methylxanthines are theophylline, caffeine, and theophylline, which can contribute to weight loss, fat depletion, and inhibit adipogenesis and stimulate lipolysis [214]. Berberine consumption significantly decreased body mass index and alleviates waist circumference (WC) [215]. Cooked mung bean may prevent obesity in mice fed with a highfatdiet and regulates lipid metabolic disorders [216]. Garlic oil had a significant anti-obesity influence on obese rats by protecting the liver from damage and regulating the body weight [217]. A significant decrease of intracellular lipid accumulation in 3T#-L1 pre-adipocyres, improvement of plasma lipid profile in HFD-induced mice, and regulation of body weight gain has been reported due to application of bound phenolics isolated from lotus seeds [218]. The ethanolic extract of Cuscuta reflexa suppressed the development of obesity in HFD-induced obesity [219]. Hunteria umbellate (K. Schum.) Hallier f. indicated both antihyperlipidaemic and anti-obesity effects which may partly be mediated via inhibition of intestinal lipid absorption and de novo biosynthesis of cholesterol [220]. Lagenaria siceraria (fruit) and Commiphora mukul (gum resin) can regulate the high fat diet-induced obesity [221]. Erigeron annuus L., and Borago officinalis L. significantly attenuated improved in body weight gain, lipid accumulation, and adipocyte size, a unique adipokine known to promote the breakdown of fat/lipids [222]. Blueberry had potential health benefits in ameliorating the development of obesity and its related comorbidities, such as chronic inflammation and type 2 diabetes [223]. Morin (3,5,7,2,4-pentahydroxy flavones) is found in some natural products such as almond (Prunus dutcis), figs (chlorophora tinctoria), guava leaves (psidium guajava), and some other Maraceae family plants [224,225]; morin treatment produced dose-dependent improvement in lipid profile and vascular endothelium protection, thus rationalizing its medicinal use in cardiovascular-related endothelial disorders, and dyslipidemia diseases [226]. In Kampo, Japanese traditional medicine, two formulas, this bofutsushosan (the composition of scutellaria root, platycodon root, glycyrrhiza, atractylodes rhizome, gypsum, rhubarb, schizonepeta spike, peony root, gardenia fruit, Japanese angelica root, cnidium rhizome, menthe herb, saposhnikovia root, forsythia fruit, Ephedra herb, ginger) and boiogito (the composition of astragalus root, sinomenium stem, jujube, atractylodes lancea rhizome, glycyrrhiza, and ginger) are supported by the national health insurance in Japan for treatment of obesity [227]. In Bangladesh, the most important medicinal plants with anti-obesity characteristics are Achyranthes aspera Linn, Aegle marmelos Linn, Alliun sativum Linn, Acorus calamus Linn, Allium cepa Linn, Bombax ceiba L., Moringa oliefera, Hibiscus sabdariffa L., Impomoea batatas L., Punica granatum L., Citrus limon L., and Zingiber officinale Roscoe [228]. One of the screening methods applied in the discovery of anti-obesity drugs is to search for potent lipase inhibitors from plant extracts; the major plant extracts that inhibit porcine pancreatic lipase (PPL) are Platycodon grandiflorum A. De Candolle, Aconitumcarmichaeli Debeaux, Chaenomeles sinensis (Thouin) Koehne, Cannabis sativa Linne, Actinidachinensis, Tribulus terrestris, Luffa cylindrical Roemer, Lilium brownii var. viridulun Baker, Pueraria thunbergiana Bentham, Crataegus pinnatifidaBunge var. typical Schneider, Nardostachys chinensis Batal, Zizyphus jujuba Miller Var. inermis Rehder, Akebia quinata Decaisne, Quisqualis indica Linne, Rehmannia glutinosa, Loranthus parasticus Merr., Schizandra chinensis Baillon, Lonicera japonica Thunberg, Dipsacus asperoides C. Y. Cheng et T. M. Ai, Perilla sikokiana Nakai, Morinda officinalis How, Prunus nakaii Leveille, Melia azedarachLinne var. japonica Makino, Poria cocos wolf, Gastrodia Blume, Bletilla striata (Thunberg) Reichenbach fil., Oldenlandia diffusa (Willd.) Roxburgh, Gentiana scabra, Cuscuta chinensis Lamark, Tetrapanax papyriferus K. Koch, Fritillaria thunbergii Miquel, Astragalus membranaceus Bunge, Patrinia villosa Jussieu, Scutellaria baicalenis Georgi, Phellodendron amurense Ruprecht, Rubus coreanus Miquel, Drynaria fortunei Smith, Eriobotrya japonica Lindley, Amomum tsao-ko Crevost et Lemaire, Cornus officinalis Siebold et Zuccarini, Forsythia koreana Nakai, Ulmus darvidian for. Suberose, Polygonum aviculare Linne, and Geraniumthunbergia. Siebold et Zuccarini [229] and Bahmani et al. [230] reported that a combination of ephedrine and caffeine, capsicin from red pepper and chili, yohimbine, guar gum extracted from the plant Cyamposistetragonolobus, glucomannan extracted from the root of Amorphophalluskonjac, Garcinia cambogia, the active ingredient from Pausinystaliajohimbe, and Hoodia gordonni have functional roles in reducing weight, improving energy, and inhibiting fat absorption, with no negative impacts in the treatment groups. The most principal medicinal plants and herbs in traditional Chinese medicine in the treatment of obesity are celastrol (Tripterygium wilfordii), Berberine (Coptis chinensis), Capsaicin (Chili pepper), Resveratrol (Polygonum cuspidatum), Chrysophanic acid/Rhein (Rhubarb), Fenugreek (Trigonella foenumgraecum L.), Curcumin (Turmeric), Radix astragali, Tea catechins GTpolyphenols (Green tea), Xiexin decoction, white tiger plus ginseng decoction, and Chaihu Shugan powder through increased leptin sensitivity, blocking fat production and accumulation, improving lipid decomposition, regulating the level of adiponectin, etc. [231,232]. Polyphenol, quercetin, caffeic acid, hydroxyflavin, and hesperetin are active constituents of mulberry leaf with possible anti-obesity impacts [233]. Capsicoside G is the main component of pepper which can block adipogenesis through activation of adenosine monophosphate-activated protein [234]. The principal active component of cocoa with anti-obesity activity is polyphenols which decrease lipids in the liver; genes in lipid catabolism, primarily in fatty acid oxidation, was up-regulated, whereas genes in lipid synthesis pathways were down-regulated, regulating obesity-induced steatosis markers [235]. Coumaric acid and ferulic acid are the main anti-obesity components of barley which may inhibit adipocyte differentiation, dysregulate lipid profiles, and prevent body weight gain [236]. Black soybean contains anthocyanin, which can markedly alleviate fat accumulation, regulate the expression of lipogenesis genes (acetyl-CoA carboxylase), and improve the levels of lipolysis proteins (hormone-sensitive lipase, lipoprotein lipase, and adenosine monophosphate-activated protein kinase) in mesenteric fat [237]. The active anti-obesity of red chili pepper, capsinoids, can suppress diet-induced obesity via uncoupling protein 1-dependent mechanism [238]. The most notable active components of garlic are S-allyl-l-cysteine sulphoxide, S-allyl cysteine which can alleviate relative masses of liver and fat tissues, hepatic oxidative stress levels, serum triacylglyceride levels, and improve fecal lipid contents in high fat diet rats, up-regulated adenosine monophosphate-activated protein kinase, adipose triacyglyceride lipase, Sirtuin 1, hormone-sensitive lipase, palmitoyltransderase 1, Acyl-CoA oxidase, whereas it down-regulated cluster of differentiation 36 [239]. Crocin of saffron can significantly alleviate total cholesterol and plasma levels of triacylglycerol [240]. Tiliroside of raspberry and strawberry may inhibit obesity-induced hepatic inflammation and muscular triglyceride accumulation [241]. Polyphenols are the active anti-obesity constituent of coffee which can regulate postprandial hyperglycaemia and hyperlipidemia, suppress lipogenesis by down-regulating sterol regulatory element-binding proteins acetyl-CoA carboxylase-1 and -2, stearoyl-CoA desaturase-1 and pyruvate dehydrogenase kinase-4 in the liver [242]. Anthocyanidins of bilberry can block adipocyte differentiation through impacting the gene expressions of the insulin pathway, reduced PPAR, sterol regulatory element-binding protein 1c and tyrosine residues of insulin receptor substrate 1 phosphorylation [243].

6. Conclusions

Many chronic diseases, asthma, etc. are associated with obesity and overweight, and the dramatic rise in obesity prevalence worldwide has become a real health concern. As obesity is a risk factor for many diseases, obesity itself may worsen the outcomes of COVID-19, which may require intensive care. Obesity/overweight is linked with increase COVID-19 mortality, and the monotonic relationship between COVID-19 infection and body mass index and risks of hospitalization have been reported. The main reasons which may contribute to obesity are reduced physical activity, excess intake of calorie loaded food, depression, pharmaceutical concomitant, food obsession, personality traits, genital/hereditary predisposition, economic growth, and lifestyle modifications. Medicinal plants, particularly edible plants have long been used as traditional knowledge to treat and prevent obesity, especially in Asian countries, because various bioactive compounds from both herbs and fruits have been found useful for anti-obesity drug discovery and development processes. Obesity is an important problem for normal growth in children, with both primary and secondary health risks such as high blood pressure, insulin resistance, hypertension, cardiovascular diseases, and different cancers. The different mechanisms which medicinal plants may affect weight loss consist of increasing levels of leptin, hypolipidemic and hypoglycemic effects, reducing fat absorption, influencing fat metabolism, enhancing metabolism, decreasing appetite, and preventing carbohydrate intake. The most important medicinal plants which are common in traditional medicinal sciences of different countries due to their anti-obesity activities are Acosmium dasycarpum (Vog.) Yakovlev, Allium cepa L., Aloe barbadensis Miller, Amorphophallus konjac K. Koch., Artemisiasphaerocephala Krasch, Betula utilis, Bupleuri Radix, Butea monosperma, Caralluma fimbriata, Corchorus olitorius L., Cuminum cyminum L., Carum carvi L., Cyclopia spp., Cynara scolymus L., Cynometra cauliflora Linn., Cynomorium songaricum Rupr., Echium angustifolium Mill., Echium angustifolium Mill., Garcinia cambogia, Gnidia glauca (Fres.) Glig, Ganodermalucidum sensu strict, Gnidia glauca (Fres.) Glig., Hibiscus sabdariffa L., Ilex paraguariensis, Justicia carnea Lindl., Juniperus communis L., Ligustrum robustum Blume, Lobelia chinensis lour, Macrotyloma uniflorum (Lam.) Verdc., Mangifera indica Linn., Melissa officinalis L., Memecylon umbellatum Burm. f., Moringa oleifera Lam., Moringa peregrine (Forssk.) Fiori., Morus alba L., Nigella sativa L., Oroxylum indicum Kurz, Passiflora edulis Sims, Pilosocereusgounellei (F.A.C. Weber) Byles and G.D.Rowley, Piper nigrum L., Populus balsamifera L., Psidium guajava L., Raphanus sativus L., Salacia chinensis L., Salvia hispanica L., Salviaofficinalis L., Smilax china L., Smilax glabra Roxb., Solenostemma argel Hayne, TabebuiaavellanedaeLorentz ex Griseb, Tinospora cordifolia (Thunb.) Miers., Urtica dioica L., Vaccinium arctostaphylos L., and Withania somnifera (L.) Dunal.