What if much of what we believe about metabolism, diet, exercise, and weight loss is wrong?
It turns out, we’ve had some serious misconceptions.
In this article, we’ll look at metabolism myths busted by the latest research.
Read on to find out what we've learned.
Latest Reserach Refutes Common Beliefs
A lot of what we believe about metabolism is fueled by fitness channels and diet fads. Some of the myths, we’d actually like to be true. But Dr. Herman Pontzer, an evolutionary biologist who’s spent two decades studying and measuring metabolism in people around the world has some surprising insights.
In his book Burn: New Research Blows the Lid Off How We Really Burn Calories, Lose Weight, and Stay Healthy, he explains how studying sedentary people as well as Hadza hunter-gatherers in Tanzania provides clarity about metabolism and metabolic rate.
Here are a few of the myths his research refutes.
The calories we consume fuel our bodies for physical activity.
Not really. Most of our calories are burned at a cellular level. Metabolism is the work that our 37 trillion cells do all day. Like little factories, our cells produce everything the body needs to function, Pontzer explains. Metabolic rate is the sum of all the energy those cells burn while doing this work.
Active people have higher metabolisms and burn way more calories than sedentary people.
Nope. Pontzer’s research finds that we all burn calories within a very narrow range – about 3,000 a day for men and 2,400 a day for women – regardless of how active we are. Surprisingly, even though Hadza people get as much physical activity a day as most Americans get in a week, they burn the same number of calories. Why? Their bodies use more calories for activity and less for unseen tasks in the body.
You can indulge in junk food as long as you work out to burn off the extra calories.
No, it’s not that simple. There’s no control dial for the energy we burn each day. Pontzer explains that our bodies are clever, dynamic products of evolution programmed to keep us from losing weight (because historically, weight loss was an indicator of slipping health). When exercise burns more calories, the body adjusts by using less energy elsewhere.
Working out more will boost metabolism and lead to weight loss over time.
False. We need exercise to stay healthy, but it won’t lead to lasting weight loss by itself. You might notice an initial weight drop when you increase exercise, but the body will adjust to stop the weight loss. After a year of exercising diligently, weight loss from exercise alone is only about five pounds.
If exercise doesn’t lead to weight loss, there’s no reason to do it.
Absolutely erroneous. Exercise is fundamental to health. When we use more energy on physical activity, our bodies use less energy reacting to stress, inflammation, and other things that make us sick, he says. Exercise helps keep our hormones balanced and inflammation low. Hadza people who get 5-10 times as much exercise don’t get heart disease, diabetes, and reproductive cancers we see in Americans and Europeans.
Aging, pregnancy, and menopause slow down metabolism.
False. We burn about the same amount of energy from age 20 to 60 and after that, it declines very slowly. What drives how many calories we burn is body mass and how much of that mass is muscle and organs versus fat, which burns fewer calories. If metabolism drastically drops after age 60 or 70, research suggests that may be a sign that cells are using more energy in unhealthy ways like creating cortisol to respond to stress or fueling chronic inflammation.
The Bottom Line for Weight Loss
With these metabolism myths busted, what’s the bottom line if we want to lose weight? Cut overall calories and overprocessed foods, which are high-calorie and offer little or no nutrients for our cells to fuel the body. If we can only eat 2,000 calories a day, what’s in those calories really matter for our health.
We also need to move our bodies for overall health. Plus, muscle mass burns more calories than fat mass so a fit body will burn calories more efficiently. Exercise is crucial, it’s just not going to cause lasting weight loss if we don’t also cut calories.
Lastly, Pontzer’s research not only busts myths about boosting metabolism – it also confirms truths about lowering metabolism. Starving ourselves or cutting calories too drastically (which makes the body think it’s starving) causes metabolism to plummet while the body conserves energy and fat stores. Again, our metabolisms are a product of thousands of years of evolution working to keep us alive.