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Metabolic adaptation refers to the process by which the body adjusts its metabolism in response to changes in energy intake or body mass. This adjustment can occur in both directions, meaning that the body can increase or decrease its energy expenditure in response to changes in energy intake or body weight.
When someone consumes fewer calories than their body requires for energy, the body will respond by decreasing energy expenditure to conserve energy. This can make it harder to lose weight and maintain weight loss over time. Conversely, when someone consumes more calories than their body needs, the body will increase energy expenditure in an attempt to counteract the excess energy.
There are several open debates in science about metabolic adaptation, including the actual magnitude of it, its relevance to weight loss, what measurement methods should be used, and the mechanisms underlying the contributory factors.
Some people have framed metabolic adaptation as so significant that it makes weight loss attempts futile. While others, including in research, have referred to metabolic adaptation as an “illusion”. So what do we actually know about this concept and what is the pragmatic significance of it?
To discuss the nuances of the topic, Alan and Danny are joined by Dr. Eric Trexler, who has published on this topic and has followed recent publications closely.
Eric Trexler, PhD
Dr. Eric Trexler is Director of Education at Stronger By Science, where he co-hosts the SBS podcast. He also is one of the four contributors to the MASS Research Review.
Eric has a prolific background in exercise science research, with more than 30 publications to his name by the time he completed his PhD at UNC-Chapel Hill.
- Weight loss and adaptive thermogenesis
- How should we define metabolic adaptation?
- Is metabolic adaptation a barrier to weight loss maintenance?
- Is metabolic adaptation an illusion?
- “Spendthrift” and “thrifty” phenotypes
- Current open questions & debates
- You can get more of Dr. Trexler’s research analysis with the MASS Research Review
- Receive our free weekly email: the Sigma Synopsis
- Relevant studies:
- Martins et al., 2020 – Metabolic adaptation is not a major barrier to weight-loss maintenance
- Martins et al., 2020 – Metabolic adaptation is an illusion, only present when participants are in negative energy balance
- Trexler et al., 2014 – Metabolic adaptation to weight loss: implications for the athlete
- Leibel et al., 1995 – Changes in Energy Expenditure Resulting from Altered Body Weight
- Related episodes:
- #208: Herman Pontzer, PhD – Constrained Energy Expenditure Model & the Evolutionary Biology of Energy Balance
- #391: Is There a Body Weight Set Point?: Models of Body Mass Regulation
- #95: Dr. James Levine – Physiological & Psychological Effects of Chronic Sitting & Low NEAT
- #124: Brent Ruby, PhD – The Human Ceiling of Energy Expenditure & the Role of Environment in Recovery & Performance
- #330: Eric Trexler, PhD – Antioxidants, Oxidative Stress & Exercise Adaptations