Metabolic adaptation is your body doing exactly what it evolved to do. It’s an elegant, sophisticated survival response, and once it kicks in, almost everything you try to do to reverse it makes it worse.
Here’s what actually happened inside my body.
The threat assessment
When my body detected chronic energy deficiency (not enough fuel coming in to cover both training and basic function) it didn’t just slow down. It ran a threat assessment. Then it went into survival mode because it determined that resources were scarce in a demanding environment. And that triggered a cascade and once that cascade started, calories in versus calories out becomes almost irrelevant.
The thyroid hits the brakes
The first thing your body does in survival mode is slow your metabolism at rest. It does this by downregulating thyroid function.
My metabolism didn’t just drop by the 250 calories that’s commonly cited for menopause. It dropped further. My body wasn’t just adapting to menopause, it was adapting to a perceived famine while also managing a high training load and chronic stress. It applied the brakes hard.
So now my 1,800-1,900 calories were being processed by a metabolism that had quietly reset itself downward. What looked like a deficit on paper was becoming maintenance. Or worse, a surplus, thanks to my slower metabolism.
Cortisol takes over
Chronic energy deficiency keeps cortisol elevated. Cortisol’s job is to mobilize energy in a crisis. It breaks down stored fuel and releases glucose to keep you going. Chronically elevated cortisol also does something that feels completely counterintuitive: it directs fat storage. Particularly visceral fat, which is abdominal fat.
Why? Because visceral fat is the most metabolically accessible in a genuine crisis. Your body is building a reserve it can actually use if things get worse. So I had a slowed metabolism and a body that was actively prioritizing fat storage. And I was adding HIIT sessions and cutting calories.
Every intervention confirmed the threat
This is the part that took me the longest to understand.
When I cut 300 calories, my body read that as the famine is real and it’s getting worse. Cortisol went up. Thyroid downregulated further. Fat storage increased.
When I added HIIT, I added the highest cortisol-spiking exercise modality there is on top of a system already drowning in cortisol. My body read that as the threat just escalated, so it defended harder.
Eat less, work harder. The two interventions every athlete reaches for. Both of them, in my situation, were throwing fuel on the fire. I was not failing the protocol. The protocol was the wrong tool for what my body was actually dealing with.
When the weight kept creeping up, I didn’t recognize the RED-S. But I did recognize high cortisol. So I took a good, hard look at the stressors in my life and realized I needed to cut back on training. It was the only stressor I had control over. Eventually, I realized I needed to take a complete break. I wasn’t just dealing with weight gain, I was also dealing with stacking injuries.
The set point shift
About a year after I stopped training, the weight gain stopped, and I’ve held steady for the past year. My body found a new, higher set point. While I’m not happy with where it settled, I know it was because my body needed to find the most efficient survival configuration for the conditions it was in.
The set point will shift again when the inputs change. Not through restriction or intensity, but through restoring energy availability, reducing the chronic cortisol load, and giving my body actual evidence that the threat has passed.
That’s what I’m working on now.
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