Is there such a thing as a good or bad metabolism?
Text: Matthias Betz
Some people seem to be able to eat whatever they like and still stay slim. Others just have to look at a hearty meal and they gain weight. What’s behind this? And can specific preparations actually “speed up” our metabolism?
Any weight gain can be attributed to a surplus of ingested energy relative to the amount of energy expended. This may sound simple, but it’s quite complicated in terms of physiology — the science of metabolic processes in organisms.
The systems that regulate our appetite and therefore our energy supply can be found in the hypothalamus. This area of the brain acts as the control center for all automatic processes in the body, such as breathing and digestion. Over recent decades, researchers have identified in ever greater detail the mechanisms in the hypothalamus that play a key role in regulating our weight. Indeed, the findings of this research have also been used to develop the weight-loss drugs that are now so successful, precisely because they act on the control center of our appetite.
The basal metabolic rate is not constant.
So far, however, much less research has been conducted into how the body’s energy expenditure is regulated. Energy metabolism is made up of several components, including not only the energy we need for movement but also the “basal metabolic rate” — that is, the energy required at rest. The latter is the largest component of most people’s energy budget nowadays and is determined by the energy demand of elementary metabolic processes such as the buildup and breakdown of protein or fat. Despite what the name suggests, the basal metabolic rate is not a constant figure. It can also be lowered — for example, if we eat less with a view to losing weight.
Initial results suggest that people who gain weight easily can actually reduce their basal metabolic rate to a lower level by fasting, although how the body regulates this is not yet fully understood. It also remains unclear whether this is a key factor in the development of obesity or whether the difference in appetite regulation is more important.
So far, there is a lack of safe and well-tolerated drugs that boost energy expenditure — in other words, that speed up metabolism. In any case, the extracts or supplements marketed online and in classified ads have no impact on energy expenditure from a scientific perspective.
Original publications
Nature Metabolism (2024), doi: 10.1038/s42255-024-01106-8
Science Translational Medicine (2023), doi: 10.1126/scitranslmed.adh4453
More articles in this issue of UNI NOVA (November 2024).