The gastrointestinal microbiota is emerging as a unique and inexhaustible source for metabolites with potential to modulate G‐protein coupled receptors (GPCRs). The ghrelin receptor [growth hormone secretagogue receptor (GHSR)‐1a] is a GPCR expressed throughout both the gut and the brain and plays a crucial role in maintaining energy balance, metabolism, and the central modulation of food intake, motivation, reward, and mood. To date, few studies have investigated the potential of the gastrointestinal microbiota and its metabolites to modulate GPCR signaling. Here we investigate the ability of short‐chain fatty acids (SCFAs), lactate, and different bacterial strains, including Bifidobacterium and Lactobacillus genera, to modulate GHSR‐1a signaling. We identify, for what is to our knowledge the first time, a potent effect of microbiota‐derived metabolites on GHSR‐1a signaling with potential significant consequences for host metabolism and physiology. We show that SCFAs, lactate, and bacterial supernatants are able to attenuate ghrelin‐mediated signaling through the GHSR‐1a. We suggest a novel route of communication between the gut microbiota and the host via modulation of GHSR‐1a receptor signaling. Together, this highlights the emerging therapeutic potential in the exploration of the microbiota metabolome in the specific targeting of key GPCRs, with pleiotropic actions that span both the CNS and periphery.—Torres‐Fuentes, C., Golubeva, A. V., Zhdanov, A. V., Wallace, S., Arboleya, S., Papkovsky, D. B., El Aidy, S., Ross, P., Roy, B. L., Stanton, C., Dinan, T. G., Cryan, J. F., Schellekens, H. Short‐chain fatty acids and microbiota metabolites attenuate ghrelin receptor signaling. FASEB J. 33, 13546‐13559 (2019). www.fasebj.org

Obesity and obesity-related disorders are reaching epidemic proportions worldwide. In this review, we summarize the accumulating studies that have emerged in the last few decades demonstrating that bioactives from different natural sources could potentially have anti-obesity effects. We carried out an extensive search of relevant literature from Pubmed, Web of Knowledge, and other online databases for studies where anti-obesity effects were shown by compounds from natural sources. Appetite suppression, lipid metabolism regulation, and increase of energy expenditure are the main mechanisms by which anti-obesity effects are exerted. Plants represent the most studied natural source of anti-obesity bioactives. Camellia sinensis is the most representative species exerting several anti-obesity effects. Moreover, probiotics (bacteria which bestow health benefit), such as strains of Bifidobacteria and Lactobacillus families, and certain prebiotics (non-viable food components that confers a health benefit on the host associated with modulation of the microbiota effects), such as insulin-type fructans, have also shown capability to combat obesity. Finally, compounds from animal sources, in particular bioactive peptides derived from milk-derived whey and casein protein digestion, high dietary calcium, and omega-3s polyunsaturated fatty acids (n-3 PUFA) present in fish oils, have also shown potential anti-obesity effects. Several anti-obesity effects have been observed in different natural bioactives providing an interesting and potentially safer and more desirable treatment strategy for the development of anti-obesity functional or medical foods.