Cranking up the cardio is commonly the first thing that comes to mind for those trying to shed weight. While more physical activity seems logical for weight loss, is it the most effective way?

On Aug. 28, 2024, Dr. Eric Trexler, a metabolism researcher at Duke University with a Ph.D. in human movement science, discussed the constrained total energy expenditure (TEE) model and explained why excessive cardio might not be the best weight loss approach.

Many assume that increasing physical activity directly boosts TEE, leading to faster weight loss. However, the additive model of energy expenditure may not always be accurate. (1) Learn more below:

The body adapts to increased physical activity by reducing energy spent on other physiological processes, maintaining total energy expenditure within a tight range. This makes it more challenging to lose weight solely by adding more cardio.

Trexler explains that if an individual increases their daily calorie expenditure by 100 kcal, they’ll likely only burn an additional 70 calories by the end of the day. The body compensates for 30% of the increased effort. This compensation follows a linear progression; it increases proportionally with the number of calories burned, leading to diminishing returns. (2)

Trexler highlights a clinical trial involving populations with high daily activity levels, such as hunter-gatherers who average 25,000 to 30,000 steps daily.

In these populations, people tend to be quite lean and have extremely low rates of cardiovascular disease.

Despite their high daily calorie expenditure, these populations did not exhibit exceptionally high metabolic rates or burn significantly more calories than people in more sedentary societies. This suggests that the body adapts to increased activity levels by becoming more efficient at burning calories.

Exercise-induced energy compensation (EIEC) is the process by which the body reduces its calorie expenditure in response to increased physical activity. This can happen through several mechanisms, such as a decrease in non-exercise activity thermogenesis (NEAT).

Trexler explained that when people exercise more, they may subconsciously move less throughout the day, negating some of the calorie-burning benefits of exercise.

Exercise is fantastic for health, but it is an extremely inefficient weight-loss tool.

Trexler emphasizes that performing more cardio to shed excess fat is an ineffective strategy — the more extreme, the less effective it becomes. He advises that an effective weight loss strategy should include some exercise, but it should primarily derive from maintaining a calorie deficit.

Key Takeaways

Prioritize a calorie deficit for weight loss. 

While exercise is good for overall health, cardio without a calorie deficit is inefficient for weight loss.

References

Pontzer, H., Durazo-Arvizu, R., Dugas, L. R., Plange-Rhule, J., Bovet, P., Forrester, T. E., Lambert, E. V., Cooper, R. S., Schoeller, D. A., & Luke, A. (2016). Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans. Current biology: CB, 26(3), 410–417. https://doi.org/10.1016/j.cub.2015.12.046

Pontzer, H., Raichlen, D. A., Wood, B. M., Mabulla, A. Z., Racette, S. B., & Marlowe, F. W. (2012). Hunter-gatherer energetics and human obesity. PloS one, 7(7), e40503. https://doi.org/10.1371/journal.pone.0040503

Featured image via Shutterstock/Dikushin Dmitry

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