It sounded like I was in a wind tunnel as the fan on the airdyne bike spun faster and faster. Sweat began to drip off my nose and the pain in my legs and lungs was becoming unbearable. All too often, this was the physiological response that I used to indicate that I had really pushed myself during a workout, the kind that I thought earned some extra calories that could be consumed later that night. I knew that the more I sweat, the more calories I burned, the more I could eat. While my airdyne bike doesn’t have a monitor that estimates total calories burned, I know many treadmills, rowers, and stationary bikes do, and let's not forget all the latest self-monitoring wearable fitness devices currently on the market. Burning more calories than I consumed was my simple formula for maintaining my weight and indulging in as much food and drink as I wanted; and it worked. Or so I thought...
Recent research suggests that my weight management plan was faulty and went against inherited adaptations that evolved in humans thousands of years ago. I was fighting against the design of mother nature, and that's not an even match up by any standards. I know it’s hard to believe, but research has revealed that humans tend to burn the same number of calories no matter how physically active they are.
So go ahead and crank out those few extra hundred calories during your workout, but don’t expect it to make much difference in your weight loss goals. Extreme calorie reduction doesn’t work for sustainable weight loss. Eventually your body will adapt to the conditions of reduced intake and weight loss will plateau and stagnate. Of course, starvation and malnourishment lead to weight loss, but that is not a process that accomplishes a healthy and stable body weight, that’s a process of dying.
A 2012 study by Pontzer et al., found that the total energy expenditure per day in men and women of the Hadza population, a hunter-gatherer tribe in northern Tanzania, was virtually the same as people living in Europe and the U.S. The Hadza hunters, with lifestyles as close to our Paleolithic ancestors as you can get, ate and burned about the same amount of calories as a pencil-pushing American men; about 2,600 calories. It should be noted however, that the Hadza people were much leaner and on average had body fat percentages much lower than their western relatives (see Table 1).
Table 1. Hunter-Gatherer Energetics and Human Obesity
Herman Pontzer David A. Raichlen Brian M. Wood Audax Z. P. Mabulla Susan B. Racette Frank W. Marlowe
Humans are not the only species who have a fixed total energy expenditure. Primate species such as apes, chimpanzees, and bonobos all burn similar amounts of calories independent of their environments. Captive primates expend the same number of calories each day as those in the wild. It seems as though evolution has expanded beyond the inheritance of traits best suited for the environment to include traits best suited for (or required for) a physiological design regardless of the environment. One of the reasons for this may be that human design requires us to shunt most of our calories to our big brains and potential reproductive output. We are metabolic machines, burning double the amount of calories per day when compared to other primate species. This is the evolutionary price we pay for intelligence.
So, what does this mean for the modern human who, in my opinion, are living more like captive humans when compared to our hunter-gather ancestors? Well, for one, please do not stop exercising. Physical movement comes with a plethora of benefits that include decreased chronic inflammation, better sleep, improved blood biomarkers, mood regulation and control, and an increase in overall brain function capabilities. Engage in physical exercise for the aforementioned reasons, and please do not hyper-focus on how many calories a particular workout or specific exercise burns. Counting calories doesn’t support our overall goal of finding a healthy and stable body weight and body fat percentage. Secondly, this research supports the idea that your diet has the greatest effect on your body weight. Not all calories are created equally and the quality and type of food matters significantly. Eat real food that is unprocessed, fresh, and sourced using sustainable processes.
Yes, cutting back on calories and increasing exercise will shed pounds for those of us who have weight to lose, but the body will eventually become metabolically stabilized and weight loss will slow or even reverse until a healthy weight is established. Think of food quality as your weight management program and exercises as your prescription for vitality. Life is too short and food is too good to live in a constant state of counting calories.
Want to dig a little deeper? References for this article:
Hendry, A. P., Kinnison, M. T., Heino, M., Day, T., Smith, T. B., Fitt, G., . . . Carroll, S. P. (2011). Evolutionary principles and their practical application. Evolutionary Applications, 4(2), 159-183.
Pontzer, H., Brown, M. H., Raichlen, D. A., Dunsworth, H., Hare, B., Walker, K., . . . Ross, S. R. (2016). Metabolic acceleration and the evolution of human brain size and life history. Nature, 533(7603), 390-392.
Pontzer, H., Durazo-Arvizu, R., Dugas, L., Plange-Rhule, J., Bovet, P., Forrester, T., . . . Luke, A. (2016). Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans [Abstract]. Current Biology, 26(3), 410-417.