Debunking Metabolism Myths: Insights from Evolution and Research
Explore the truth about metabolism and debunk common myths. Learn how evolution and modern research reveal the complexities of metabolism, activity, and aging
By
July 30, 2025
When it comes to health and fitness, metabolism is often at the center of the conversation. We’ve all heard it—“boost your metabolism to lose weight” or “you have a slow metabolism, that’s why you can’t lose weight.” But how much of that is actually true? Crystal McLean, RD sheds light on how our metabolism really works, drawing from both our evolutionary history and modern research to help us better understand how our bodies are designed to adapt and thrive.
Our metabolism is far more complex than just a simple measure of how fast we burn calories. According to Crystal McLean, RD, our bodies are equipped with multiple energy systems that help us metabolize nutrients. These systems evolved as a way for our ancestors to survive in a world where food was scarce and hard to come by. Before industrialization, there were times of resource shortages. Our bodies adapted to protect us during those periods of scarcity. This evolutionary resilience means that we’re designed to make the most of the energy available to us, whether we’re sedentary or active.
Our bodies’ ability to adapt is also part of what makes us so resilient today. Over time, we have developed ways to store energy efficiently, regulate hunger, and even adjust how much energy we expend based on the food available. These mechanisms are crucial in understanding why metabolism isn’t as simple as a one-size-fits-all measure of energy output. Our body’s energy systems are incredibly dynamic, allowing us to adjust depending on our environment and needs.
A fascinating study conducted by researchers at Duke University examined metabolism in various traditional societies. In particular, they studied populations like those in rural areas of Tanzania (though it may not have been exclusively this group). The study found that people who lived highly active lifestyles, like farmers or herders, had metabolic rates similar to those in the U.S. despite their demanding physical activity. This challenges the conventional idea that increased physical activity automatically speeds up your metabolism.
What this study illustrates is that metabolism isn’t just about how much you move. It’s about how your body processes and utilizes the nutrients you consume, and how your body’s energy needs are influenced by genetic, environmental, and lifestyle factors.
This insight is critical because it challenges the assumption that simply working harder or increasing exercise intensity will directly result in a faster metabolism. Factors like stress, sleep, and even the types of food we eat all influence our metabolic rate.
You’ve probably heard that your metabolism slows down significantly as you get older. But according to research, this isn’t entirely true. In fact, metabolism remains relatively stable from adulthood until around age 60. This research debunks the idea that metabolism drastically slows with age, offering a clearer understanding of how our bodies function over time. While our metabolism does change as we age, it doesn’t take a dramatic dip until later in life, which is helpful to know when it comes to setting realistic health and fitness expectations.
The insights shared by Crystal McLean, RD, reveal that metabolism is far more complex than we give it credit for. Our bodies are designed to adapt and thrive based on our environment, and understanding this adaptability can help us make smarter choices in our fitness and nutrition. By taking a step back and recognizing that metabolism isn’t just a speedometer for weight loss or gain, we can make better-informed decisions about our health and wellness journey.
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