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.
Grams of Carbs. Carbohydrates contain 4 calories per gram. If you typically consume around 2,000 calories per day, 45 to 65 percent of your calories is equivalent to 225 to 325 grams of carbs. An 1,800-calorie diet requires 202 to 293 grams of carbohydrates, while a 2,500 calorie diet allows you to have 281 to 406 grams.