Introduction: Obesity is a systemic disease leading to many complications. One of the causes of obesity is excessive energy intake in relation to its expenditure. Assessing portion sizes and estimating caloric intake is crucial in maintaining a healthy body weight and combating obesity. Objectives: To evaluate the impact of BMI on the perception of portion sizes and their estimated caloric content. Patients and methods: The anonymous survey was filled out by 205 patients. The survey contained questions regarding different meals. Pictures of main meals were presented and individually assessed by the study participants. Next, they were divided into groups, individuals with normal weight (BMI < 25 kg/m²), who were overweight (BMI 25–29.9 kg/m²), and with obesity (BMI ≥ 30 kg/m²), to analyze the differences in food perception and caloric estimation. Results: The study did not demonstrate significant differences in the subgroups’ estimated portion sizes of most main meals. No statistical significance was found in the estimated caloric content of the indicated main meal portions across the studied groups. Obese, overweight, and normal-weighted patients assess food portion size similarly. Conclusions: BMI has no significant impact on caloric estimation. The majority of the population estimate the caloric value of the meals inappropriately. Nevertheless, patients with excessive body weight (overweight and obesity) have a tendency (but not statistically significant) to underestimate the caloric value of full meals compared with people with normal BMI. Incorrect calorie estimation may lead to consuming bigger meal portions in patients with overweight and obesity.

Obesity is a disease which is currently one of the most serious problems affecting approximately 650 million people worldwide. Improper lifestyle is considered the primary cause of the disease; however, many other factors contribute to the problem. In recent years, attention has been drawn to the role of gut microbiota in developing and controlling obesity and overweight. Microorganisms in the gastrointestinal tract are responsible for the fermentation of certain nutrients, causing efficient digestion, stimulation of intestinal transit, vitamin production, and modulation of the host’s immune system. Numerous studies have demonstrated that gut microbiota composition differs between obese individuals and those with a normal body mass index (BMI). It has also been shown that altering gut microbiota can influence the phenotype of the host organism, promoting metabolic changes, including BMI reduction. Recent studies aimed at using probiotics to modify gut microbiota composition to reduce body weight are still inconclusive.

Introduction: The major cause of obesity is excessive calorie intake. Inappropriate dietary habits, like increased meal frequency, portion sizes, or amount of snacks consumed contribute to obesity development. Potential differences in the perception of snacks by people with different BMIs may be one of the causes of obesity. Assessment of the perception of snacks by people with excessive and normal body weight will allow us to check whether this parameter actually has an impact on the development of obesity. Materials and Methods: A survey study was conducted to check differences in assessing different snacks and beverages by individuals with varied BMIs. Participants analyzed snacks on presented photographs and assessed portion sizes, estimated caloric content, assessed whether the meal was healthy, and determined whether the indicated portion would be sufficient to satisfy their hunger. The study population was divided according to body mass index (BMI) into individuals with normal weight, overweight, and obesity. Additionally, the study group was divided according to gender and age. Results: There were no statistically significant differences in the majority of the studied parameters concerning BMI; however, the study revealed relatively low education level regarding caloric assessment. Conclusions: BMI seems not to have an influence on calorie and portion size perception of snacks. The majority of the population wrongly assessed the calorific value of snacks, which might contribute to obesity development. People have a tendency to overestimate the caloric value of snacks. Women assess the portion size of highly processed snacks as larger than men do.