signaling pathways of endocrine hormones

9, 10 Accumulating evidence shows that unhealthy lifestyles lead to obesity. 7, 8 Indeed, genome-wide association studies have identified more than 300 single-nucleotide polymorphisms and 227 genetic variants related to obesity, although their functional impact on the obese phenotype is still a mystery. Usually, obesity occurs when the body’s energy intake exceeds energy expenditure, which is influenced by inherited, physiological, and/or environmental factors. 3, 4, 5, 6 Although the positive relationship between obesity and individual mortality/morbidity has been recognized for more than 20 years, the global prevalence of obesity continues to increase, and the WHO estimates that one out of five adults worldwide will be obese by 2025. 2 The World Health Organization (WHO) describes obesity as one of the most blatantly visible and under-appreciated public health problems that increase the risk of multiple diseases, such as type 2 diabetes (T2D), cardiovascular disease, hypertension, nonalcoholic fatty liver disease, and certain cancers. 1 According to a report by the Non-Communicable Disease Risk Factor Collaboration, the prevalence of obesity increased worldwide from 1975 to 2016, ranging from 3.7% in Japan to 38.2% in the United States. Obesity, defined as a body mass index (BMI) ≥30 kg/m 2, is a complex chronic disease characterized by an excessive accumulation of fat or adipose tissue in the body. The evolving knowledge of signaling transduction may shed light on the future direction of obesity research, as we move into a new era of precision medicine. We also discuss the current anti-obesity drugs, as well as weight loss compounds in clinical trials, that target these signals. In this review, we summarize recent advances in the pathogenesis of obesity from both experimental and clinical studies, focusing on signaling pathways and their roles in the regulation of food intake, glucose homeostasis, adipogenesis, thermogenesis, and chronic inflammation. Over the past decades, the pathophysiology of obesity has been extensively investigated, and an increasing number of signal transduction pathways have been implicated in obesity, making it possible to fight obesity in a more effective and precise way.

Although lifestyle intervention (diet and exercise) has remarkable effects on weight management, achieving long-term success at weight loss is extremely challenging, and the prevalence of obesity continues to rise worldwide. Characterized by excessive fat accumulation in the body, obesity sharply increases the risk of several diseases, such as type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and is linked to lower life expectancy. Obesity is a complex, chronic disease and global public health challenge.

Signaling pathways of endocrine hormones