Definition. The host (also called the susceptible host) is the human body: someone who is at the risk of infection. Infections do not necessarily occur when pathogens enter the body of the person whose immune system is functioning normally.Whether or not a pathogen will result in infection depends upon several factors related to the host (the person exposed), the pathogen itself, and the environment.nfections do not necessarily occur when pathogens enter the body of the person whose immune system is functioning normally. Whether or not a pathogen will result in infection depends upon several factors related to the host (the person exposed), the pathogen itself, and the environment.
You can find out how many calories are in a food by looking at the nutrition facts label. The label also will describe the components of the food â how many grams of carbohydrate, protein, and fat it contains. Here's how many calories are in 1 gram of each: 1  carbohydrate â 4 calories.  protein â 4 calories.
Carbohydrates. Each gram of carbohydrate contains 4 calories. Carbohydrates should comprise 45 to 65 percent of your daily calorie intake. Using these recommendations, if you require 2,000 calories per day, you should consume 225 g to 325 g of carbohydrates daily.at. Fat is the most energy-dense nutrient, which means that it contains the most calories per gram. Each gram of fat provides you with 9 calories. Fat should comprise 20 to 35 percent of your daily calorie intake.