Public gyms and fitness clubs promote active lifestyles. At the same time, numerous nutritional errors and the phenomenon of incorrect supplementation are being observed among the given study group. Behavior can lead to malaise, injury, or lack of progression. One of the most serious mistakes is the incorrect level of protein in the diet. The aim of the study is to assess the quantity and quality of protein consumed by men undertaking recreational strength training in Szczecin. The study involved 35 men aged 18–35, practicing amateur strength training, from Szczecin (Poland). The author’s questionnaire collected information on supplementation, physical activity, and subjective assessment of nutritional knowledge. The obtained test results were subjected to statistical analysis performed in the Statistica12 program. On average, respondents consumed 1.8 g of protein/kg, with the highest recorded conversion rate of 3.7 g of protein/kg of body weight, and the lowest of 0.9 g/kg of body weight. Total protein consumption ranged from 70.2 to 295.7 g, and the average value was 147.8 g (22%), which differs from the study group, that is, 129–133 g, which gives 14% energy proteins. It was found that the protein supplementation, on average, provided 31% of the total protein intake of the study group. The results show inappropriate dietary behavior regarding food supplementation among the examined group. Further education on the nutritional value of the food and a healthy and balanced diet is being recommended for the individuals practicing strength sports.