It is commonly thought that working out is one of the most important aspects of weight loss projects. However, no matter how generally beneficial exercise is, most of weight loss is done in the kitchen. There are extremely few people (if any) who can efficiently burn more energy than their intake capabilities – and those among us, who have to keep tabs on our scale numbers, for sure are not one of them 😊

Benefits of exercise

Working out has a lot of positive effects on our health and should never be seen as something that is an option in life. One of the most important roles of exercise is its impact on insulin sensitivity. Having cells that respond well to insulin is vital and one of the foundations of good metabolic health. If cells are resistant to insulin, it will leave us constantly hungry, while at the same time physiologically undernourished. Insulin resistance also diminishes our capability to use our own fat deposits as a source of energy and it’s just really a shortcut to the obesity vicious circle. Also worth noting: growing research shows that insulin resistance is the underlying condition of almost all modern chronic diseases: diabetes, cardio-vascular disease, dementias and cancer. Working out is a direct protection against detrimental processes that lead to obesity and declining health.

Exercise as energy expenditure

So far the exercise was understood very mechanistically: if we burn X in 23 hours, and Y in an hour of exercise, the sum of the burnt energy in 24 hours equals X+Y. Well, it seems that this is oversimplifying it. The amount of energy expenditure in no-exercise period can decrease because of the energy expenditure while exercising. Obviously, there’s a lot to learn about how the energy expenditure systems are interrelated.

Exercise decreases resting energy expenditure

If you have ever engaged in regular and intense exercise you might have noticed that you ate more than usual in that period. Sometimes this is due to our tendency to reward ourselves with food, but sometimes it’s really about increased hunger. Often it also happens that we get slightly more lazy or even sluggish outside our workout routine. These are all known phenomena but the explanation as of why they occur has been quite elusive. Until now. The researchers of the Vanderbilt University School of Medicine have set up an interesting experiment with mice that shed some light into these interesting questions. Using special infra-red equipment they were observing mice that were set up with a wheel and had as much food as they wanted available to them. They found out that mice that did a lot of voluntary wheel running didn’t eat more than usually, but in the “off-wheel” period they were just dozing around, not being inquisitive around the cage as they tend to be. Taking all the measurements into the account, the researchers calculated that exercise increased mice’s energy expenditure – but only slightly. Common sense would suggest that their energy expenditure would increase up to 50% more, but it didn’t. Why it happened is still unclear, but the scientists presume that the energy expenditure homeostasis mechanism is at work (Lark et al., 2018).