Many fast food establishments now list the number of calories each item contains. However, this is only part of the consideration of whether it is healthy or not.<br /><br />Fast food is typically poor in terms of nutrition. According to a 2015 review, fast food tends to contain various substances that are generally unhealthy. It is high in sugar, salt, saturated or trans fats, and many processed preservatives and ingredients. It also lacks some beneficial nutrients.<br /><br />However, not all fast food has negative impacts, and a person can make an informed choice by researching the nutritional content of particular fast food items. People can find this information on the websites of most major restaurants.<br /><br />That said, even the more healthy fast food items are generally high in sugar, salt, saturated fats, and trans fats. The Office of Disease Prevention and Health Promotion notes that the typical person in the United States consumes too much of these food components.<br />Fast food breaks down quickly, causing a rapid spike in blood sugar because of the refined carbohydrates and added sugar. In turn, this causes an abnormally large rusted Source insulin surge, resulting in a drop in blood sugar. This can cause people to feel tired. Insulin promotes further hunger within a short time after the meal.