Final answer:
At a lower Respiratory Exchange Ratio, a higher percentage of our energy is derived from fat metabolism. As RER decreases, this indicates increased fat oxidation for energy. Understanding RER is pertinent when considering the sustainability and environmental impact of various energy sources.
Step-by-step explanation:
At a lower Respiratory Exchange Ratio (RER), a higher percentage of our energy is derived from fat metabolism. The RER is a measurement used to determine which macronutrient (fats or carbohydrates) the body is utilizing to produce energy. When the RER value is lower (close to 0.7), it indicates that the body is using a greater proportion of fats for energy. Conversely, at a higher RER (close to 1.0), the body is primarily using carbohydrates for energy. This concept of energy source utilization can be applied to understanding the efficiency of different types of food energy consumed and the sustainability of various energy resources, including fossil fuels and renewable sources.
In discussions about global energy consumption, it's noted that a substantial portion is provided by the combustion of fossil fuels. The efficiency of these and alternative energy forms, such as biofuels, is often measured in terms of Energy Returned on Energy Invested (EROEI). The lower energy density of biofuels compared to fossil fuels, and the high carbon emissions from fossil fuel combustion, highlight the need for sustainable and more environmentally friendly energy sources.