Daily Update 4.3
Week 7: Module 4: Date 3/14/13
Calories are made up of fat, protein and carbohydrates. Each of these has a different ratio of grams to calories as can be seen in the image below.
As you can see fats have a much higher potential for calories by weight. This difference is due to the chemical make up and the reaction that occurs when these ingredients are metabolized. Essentially fats have a higher carbon ratio and therefore create more energy. Both carbohydrates and proteins have four calories per gram, but they are quite different. These differences are again related to the chemical composition and the chemical process that occurs when they are metabolized. Carbohydrates are a simpler substance and create a quicker energy using sugars, the excess of which is stored for later use. Proteins are made up of complex molecular chains which are broken down into single amino acids and are used for building and maintaining the body.
When planning for a physically challenging expedition it is important that you use all of these in the correct ratio in order to maintain a healthy body. We are going to look at one of the meals that the crew is eating and analyze it.
This is a typical breakfast of oatmeal for the crew. 
The columns in the chart from right to left are: ingredients, calories/gram, weight in grams, volume, volume and energy. The calorie/gram ratio is derived from the nutritional label that is included on most food packaging. A typical serving of this oatmeal is 81 grams and contains 324 calories: divided, this equals 4 calories/gram. Once you are aware of that you can adjust the volume to achieve the calories that you need to eat. The rest of the ingredients all go through the same process. The last ingredient is coconut oil, which is a pure fat so has 9 calories/gram. It is ingredients like these that are added on expeditions to bring up the caloric content of a meal.
Imagine if you had to go through this process with every meal you ate?