Obesity is a chronic disease, which is often accompanied by disorders of the carbohydrates and lipid metabolism, as well as metabolic complications concerning the circulatory system. It is a disorder of homeostasis of energy transformation, caused by excessive supply of energy contained in food which exceeds the needs of the body, consequently leading to increased storage of excess kilocalories in the form of adipose tissue. The incidence of obesity in the world has more than doubled between 1980 and 2014 and currently affects more than 600 million people. This is primarily due to increased food availability, a sedentary lifestyle, as well as a high-fat and high-carbohydrate diet. These facts are a consequence of socio-economic changes which took place in recent decades. One of the factors that can play an important role in the prevention of obesity or reduction of excessive body weight is the modification of intestinal microbiota composition. Recent studies have shown that a diverse, properly functioning microbiota secures the adequate use of energy supplied with food and suitable storage in the body. Probiotic bacteria can contribute to weight loss in two ways. First of all, microbiota of people characterized by the correct quantitative and qualitative composition is much more energy-efficient and contributes to the increased excretion of undigested food residues as compared to the microbiome of people diagnosed with intestinal dysbiosis. Weight reduction due to taking probiotics may also be related to its effect on the regulation of carbohydrate and lipid metabolism in the organism. This article reviews the current clinical studies on the potential relationship between intestinal microbiota and changes in anthropometric parameters concerning people with excessive body weight.