The two most relevant factors in obesity development are overeating and sedentary lifestyle. Energy density varies according to the food, but all foods with high or low caloric content have the capacity to favor weight gain if ingested in excessive amounts.

In the prevention and treatment of obesity, the nutritional Education and the promotion of physical activity are preferable to the use of fees on the most energy-dense foods. Some types of fat, saturated or trans fats, are detrimental to cardiovascular health, as opposed to others, such as monounsaturated fats, which are not, so anti-saturated fees have been created. In this sense, there are several programs of study that correlate an increase in the price of some foods with a decrease in their consumption, although it is reasonable to think that, for example, an anti-trans tax will have more effect in countries where their consumption is higher.

Spain does not consume as much trans fat as other non-Mediterranean European countries and, therefore, it is to be expected that this tax would have less impact on population health. In addition, consumption is influenced by factors such as consumer habits and tastes, the presence of alternatives to this product on the market or its price in relation to the purchaser's income, which makes it more complex to obtain a forecast of the effectiveness of the tax. The alternatives are diverse: educate people about a healthy per diem expenses and avoid the spread of inadequate diets, achieve an understandable food labeling and regulate its advertising, lower the price of those with a more favorable nutritional profile , promote the research and development of healthier alternative foods and recognize the effort of the companies that do so.