Intrinsic control and environmental factors in food consumption related to obesity
Obesity results from a complex interactions of genetic, hormonal, physiological, anatomical, psychological, behavioral and environmental factors causing an imbalance between energy intake and energy expenditure. According to the World Health Organization estimated number of obese people around the world has doubled from 1980, and in 2014 39% of adults aged 18 years and over were overweight (body mass index ≥ 25 kg/m2), and 13% were obese (body mass index ≥ 30 kg/m2), meaning that more than 600 million people worldwide is obese.
Obesity is associated with low-level chronic inflammation and represents a major risk factor for cardiovascular and metabolic diseases, but also some cancers. Centers that regulate food intake and energy balance are placed in the hypothalamus. Chemical signals are transmitted between hypothalamic neurons, and that neurons also affect the secretion of different hormones that are important for maintaining energy balance and metabolism. Moreover, genetic predisposition is also risk factor for obesity development. Key neuronal populations for maintaining energy balance are the orexigenic agouti related peptide (AgRP)/neuropeptide Y (NPY) neurons and the anorexigenic proopiomelanocortin (POMC) neurons. This review attempt to present the prevalence and the major pathways regulating energy balance that may be affected by many environmental and social factors, such as emotions and human behavior and can lead to obesity.