Metabolic Adaptation during Fat Loss
Metabolic Adaptation, a complex set of physiologic changes, tends to be the reason most people stall in their weight-loss journey.
As a caloric deficit becomes more severe and/or prolonged: Total Daily Energy Expenditure (TDEE) decreases due to various mechanisms:
- The Thermic Effect of Food (TEF) secondarily decreases.
- Non-Exercise Activity Thermogenesis (NEAT) decreases.
- Resting Metabolic Rate (RMR) decreases.
- Thyroid hormones, Insulin, Testosterone, and Leptin become negatively affected.
- Mitochondria, and the body as a whole, become more efficient in conserving energy.
All of these added together are what leads to the eventual “stall”. It has also been shown that adaptation to a fat-loss diet can lead to increased appetite and food intake. Which is the body’s compensatory mechanism for preventing starvation. This is one of the largest hurdles when trying to prevent weight-regain.
For continued fat loss progress, two primary interventions are then required in isolation or in combination to counter these effects: increasing activity and/or dietary alterations.