When I tell someone that they should stop exercising if they want to lose weight, they’re always dumbfounded. They still believe the old “eat less, exercise more”, contrary to their observations on their own body. They can’t keep weight off or are even fatter, and are often hungry. We know that leptin controls all energy production in the body. Leptin informs your brain about the energy status throughout your body. It is mostly made by adipose tissue (fat cells). If we are sensitive to leptin, it helps regulate your energy stores by inhibiting hunger. It does this in the arcuate nucleus of the hypothalamus. The hypothalamus is the size of a pea and controls the fuel requirements of the 20 trillion cells in the human body. A remarkable feat. You can test in the mirror whether you are sensitive to leptin. If you are obese, it is very likely that you are insensitive to leptin.
There’s also an interesting group of proteins called uncoupling proteins (UCPs). So far there are five known types of uncoupling protein in mammals. They are cleverly called UCP1 through UCP5. These proteins are found in the inner mitochondrial membrane. They are capable of dissipating the proton gradient from the mitochondrial matrix to the mitochondrial intermembrane space. Instead of doing work that makes ATP, heat is created. Let’s look closer at UCP3.
UCP3 allows leptin to work inside of muscle cells. To do this optimally it needs leptin and thyroid hormones to function perfectly simultaneously. It allows muscle to shift from regular energy production to heat production, without making ATP. As a consequence, there are less reactive oxygen species (ROS) created at the mitochondrial level. This is an alternative pathway to deal with excess energy. This is the primary pathway where fat burning occurs peripherally in the human body. However, it needs leptin and thyroid hormones to work properly and if you are obese, leptin is not working properly. So, the excess energy is sent back to adipose tissue. In due time, this can cause problems.
Let’s go back to our muscle cell. If you’re firing right, you can burn whatever fuel you receive (which one doesn’t matter when in season). If you are fat, you cannot do this. The excess heads back to adipose tissue. But the muscle cells are still in need of energy. Thus, a signal is sent to the gut to eat more so that muscle cells get fuel. You do this over and over but the muscle never gets the right amount to meet demands. Remember, you’re exercising more. Now you’re frustrated because no matter how hard you exercise, it’s difficult to lose the weight. On top of that, as you keep pounding this, the muscles keep on getting excess calories. This clogs them up with advanced glycoxidation end products (AGEs) from sugar and advanced lipoxidation end products (ALEs) from fat. Then type two diabetes occurs and you are in a whole new world of problems.
Therefor it is important to think about your context before you jump into exercise.