Document from the year 2019 in the subject Engineering - Industrial Engineering and Management, , course: Business, language: English, abstract: The main objective of this study is to utilize an engineering concept in order to propose a mathematical model to correlate consumer spending, utility and income. The difference between the proposed model and the Keynesian consumption theory is explained by the fact that the Keynesian consumption theory takes into account the consumption of costumers with no income. The effects of marketing, bank loans and credit debt on consumer spending are also analyzed using the general equation of transport phenomena and mathematical models are presented for the first time. Based on a case study, marketing has increased the utility (driving force) by 61%. Taking into account the theory of consumption smoothing, bank loans also provide the consumer with additional spending power by decreasing the resistance for consumption. In case of excessive debt, customers might spend the money only to buy the utility in order to be able to repay the debt. In this situation, the effects of debt are described in the proposed engineering model as a decrease in income (extra resistance to spend money).