Final answer:
Dinitrophenol (DNP) is an uncoupler that makes the inner mitochondrial membrane leaky to protons, which leads to a decrease in ATP synthesis and an increase in energy expenditure in the form of heat.
Step-by-step explanation:
Protons (H+) cannot pass through the inner mitochondrial membrane's lipid bilayer very easily. Rather, protons are actively transported across the membrane by protein complexes found in the inner mitochondrial membrane, including ATP synthase and electron transport chain components.
These proteins produce a proton gradient, which is essential for the synthesis of ATP, the cell's energy currency. Gaining or losing weight has no direct effect on how permeable the inner mitochondrial membrane is to protons.
On the other hand, dietary modifications and imbalances in energy can impact mitochondrial metabolic activity, which in turn affects energy production and consumption.