**Table 2.**

 *Mean hormone levels in obese patients.*

In recent years, there has been increasing information about the effects of incretins, which are a group of gut-derived hormones, on the regulation of body weight. Modern pharmacological therapy of obesity is associated with the introduction of GLP-1 (glucagon-like peptide-1) agonists, the level of which is significantly reduced in overweight and obese people irrespective of disorders of carbohydrate metabolism. Incretin hormones, such as GLP-1 and GIP (glucose-dependent insulinotropic peptide), are secreted from the gastrointestinal tract into the portal circulatory system in response to nutrients. In a nutrient-dependent manner, incretins have been shown to contribute to lowering blood glucose levels by increasing insulin secretion, decreasing glucagon secretion, and decreasing the rate of gastric emptying. The main effect of GLP-1 is glucose-dependent stimulation of insulin secretion by pancreatic beta cells. GLP-1 slows down the rate of gastric emptying, which helps to reduce fluctuations in postprandial glycemia [8, 9]. GLP-1 also enhances the feeling of satiety and reduces food intake, by providing prolonged stimulation of mechanoreceptors and satiation receptors. Decreased food intake may be mediated by a direct effect of GLP-1 on sensory neurons located in the upper gastrointestinal tract or by a direct effect on the central nervous system because GLP-1 receptors are present in the hypothalamic centers that regulate food intake.

Physical activity combined with a balanced diet is the basis for the prevention and normalization of weight gain and obesity. No modern guidelines for weight correction, impaired carbohydrate metabolism, prevention, and treatment of cardiovascular complications can be provided without a primary emphasis on the need for physical activity. At least 150 min per week of moderate-intensity physical activity is the minimum required to ensure active metabolism of basic, carbohydrate and fat metabolism. For example, the American Diabetes Association currently provides the following recommendations for physical activity/exercise for people with carbohydrate metabolism disorders. Daily exercise, or at least not allowing more than 2 days to elapse between exercise sessions, is recommended to enhance insulin action. Adults with type 2 diabetes should ideally perform both aerobic and resistance exercise training for optimal glycemic and health outcomes. Structured lifestyle interventions that include at least 150 min/week of physical activity and dietary changes resulting in weight loss of 5–7% are recommended to prevent or delay the onset of type 2 diabetes in populations at high risk and with prediabetes [10]. To date, the influence of physical activity on the pathogenetic risk factors of overweight and obesity has been proven, including optimization of the secretion of adipose tissue hormones, incretins and reduction of low-gradient nonspecific inflammation [11, 12].

The most convincing data on the effects of physical activity on adipose tissue hormones concern leptin. It has been shown that short-term exercise does not affect leptin levels in healthy people. However, longer and more intense exercises (≥60 min), which are associated with increased energy expenditure (≥800 kcal), lead to a decrease in leptin levels [13, 14]. In general, lifestyle changes that result in weight loss contribute to the normalization of serum insulin and leptin levels [15].

An inverse relationship was also found between physical activity and proinflammatory cytokine levels in obesity, diabetes, and metabolic syndrome. It is believed that the positive effect of exercise, which is partly mediated by changes in the profile of adipokines, is an increase in anti-inflammatory cytokines with a decrease in proinflammatory ones. This effect was described at the level of gene expression, protein ligands, and receptor binding [16]. For example, exercises increase insulin sensitivity by lowering TNF-α, C-reactive protein, and increasing adiponectin. Interleukin-6 is the first cytokine that appears in the bloodstream during exercise, and its levels

*Personalized Strategy of Obesity Prevention and Management Based on the Analysis… DOI: http://dx.doi.org/10.5772/intechopen.105094*

increase exponentially in response to exercise [17]. The increase in IL-6 levels in plasma caused by exercise correlates with the muscle mass, as well as with the mode, duration and, especially, the intensity of exercise. Infusion of recombinant human IL-6 (rhIL-6) in humans simulates the IL-6 response to exercise and prevents an increase in plasma TNF-α [18]. Inhibition of IL-6-induced TNF-α production has also been shown in cultured human monocytes. Furthermore, IL-6 stimulates the release of other anti-inflammatory cytokines, including IL-10 and IL-1Ra. These and other experiments suggest that the anti-inflammatory effects of exercise are partly mediated by IL-6 levels [19].

It has also been shown that normal physical activity can affect glucose-induced GLP-1 secretion [20]. The more time spent in physical activity, the more pronounced is the glucose-induced GLP-1 response irrespective of insulin sensitivity. This indicates a positive effect of normal moderate-intensity physical activity on GLP-1 secretion that may help improve glucose regulation and reduce the risk of type 2 diabetes [21, 22]. Therefore, physical activity contributes not only to weight normalization but also improves metabolic disorders characteristic of obese and overweight people.
