Glycogen storage in human organism is providing reserve source of glucose which is critical for normal functioning of the nervous system during periods between meals and is also important for many other tissues. Overwhelming excessive consumption of carbohydrates and decreasing physical activity among the world population lead to dramatic increase in incidence and mortality related to cardiovascular diseases, metabolic syndrome and diabetes mellitus type 2. There is an observation that many interventions with proved clinical efficiency like physical activity, intermittent fasting, caloric restriction and some pharmacological treatments have in common the ability to decrease content of glycogen in the liver and skeletal muscles. This effect leads to increased ability of these organs to uptake the next dose of glucose and store it in the form of glycogen. Moreover these interventions lead to significant life span extension, provide better body fitness and prevent development of multiple age-related diseases. In contrast excessive glucose load and saturation of tissues with glycogen provide a metabolic shift toward synthesis of fatty acids by liver. In advanced stages decreased glucose tolerance, insulin resistance, hyperinsulinemia, fatty liver disease, impairment of liver function and derangements of cholesterol metabolism are observed. It is suggested that noninvasive measurement of glycogen content in tissues could serve as important diagnostic and follow-up parameter for clinical practice and healthy lifestyle in wide population groups.