Energy metabolism in animals is typically calculated in three different ways. The first way is to quantify the difference between the energy value of all food consumed and energy value from waste. This assumes no change in the physiology of the animal and is typically only accurate across long periods of time. The second method for calculating metabolism is to quantify the total heat production of animals compared to the food that they consume. This method is considered very accurate but is very complex and difficult to calculate. The last method is the most commonly practiced method in the field. This third method measures the oxygen levels in oxidation processes and assumes no anaerobic metabolism. This method is generally considered to be very accurate and the source of energy (fat, protein, or carbohydrates) is not of importance. It also assumes that the amount of heat generated per liter of oxygen during metabolism is consistent.
Comments
One Small Edit
This paragraph is pretty perfect! My only suggestion is to remove the second "method" in the sentence where you begin talking about the third method, as it is a bit repetitive.
Suggestion
The actual setup of the paragraph is good, you introduce that there are three ways then explain each in detail. If i could suggest anything it would be maybe change up the beginning of the different sentences so they dont all begin with "This method."
It is a good paragraph but
It is a good paragraph but when you said "The last method is the most commonly practiced method in the field." and then go on and say "the thrid method" is quite repetitive. Try just jumping right in since you already established a third method.