Stress Physiology
Cortisol isn’t the enemy, chronic stress is: comfort eating is a tired brain asking for fast fuel, and a relapse is expected, not failure.
Stress and cortisol[G] are not enemies—they are a biological regulatory system. Short-term stress is adaptive; prolonged psychological stress, however, can impair metabolism, appetite control, and microbiota[G] balance. Low carbohydrate intake alone does not cause chronic cortisol[G] elevation, but poor execution—sleep deprivation, electrolyte deficiency, excessive caloric deficit—does. Stress management, proper nutrition, active recovery, and microbiota[G] stabilization are integral parts of metabolic therapy.
Stress and cortisol[G] are not enemies, but a biological regulatory system: short-term stress is adaptive, yet prolonged psychological stress can impair metabolism, appetite control, and microbiota[G] balance. Low carbohydrate intake alone does not cause chronic cortisol[G] elevation, but poor execution – sleep deprivation, electrolyte deficiency, excessive caloric deficit – does. Stress management, proper nutrition, active recovery, and microbiota[G] stabilization together form the foundation of metabolic therapy.
Chronic stress can indeed elevate cortisol[G] levels, increase appetite, and reduce self-control. “Comfort eating” in this context is often a biological response: the body seeks rapid energy. This is not a weakness, but a nervous system signal. Stress and sleep deprivation together are particularly damaging to insulin sensitivity[G] and increase abdominal fat storage – which is why stress management is an integral part of metabolic therapy.
It is important to clarify a common misunderstanding. Controlled studies show no sustained cortisol[G] elevation from low carbohydrate intake alone under normal caloric intake and proper implementation. The diet itself is not a chronic stressor; the hormonal response always depends on the complete biological environment.
Cortisol[G] is not a “bad hormone.” It participates in gluconeogenesis, aids energy mobilization, regulates circadian rhythm[G], and has immunomodulatory effects. In the short term, it helps adapt to exercise, cold, or fasting. The problem is not the hormone’s existence, but sustained, uncontrolled psychological stress.
If someone experiences stress or fatigue while following a low-carbohydrate diet, often other factors are at play:
It is important to distinguish between metabolic stress and psychological stress. Exercise, cold, or fasting are metabolic stressors that trigger adaptation. Chronic psychological stress, however, exhausts the system. Sustained activation of the HPA axis[G] (hypothalamus[G]–pituitary–adrenal) increases gut permeability[G], alters microbiota[G] composition, and sends inflammatory signals to the brain – impairing mood and self-control [64]. Stress management therefore directly affects the gut–brain axis.
Relapse management deserves special attention. If relapse occurs – an episode of comfort eating, a missed day, a stressful week – this is biologically expected, not a failure. What to do in such a situation:
Stress management is not a luxury, but therapy. Short breaks, slow breathing, adequate sleep, electrolyte intake, and gentle movement stabilize cortisol[G] rhythm. Stress is a signal, not a judgment – if you recognize the difference between metabolic and psychological stress, it becomes easier to find balance.
3-day objective summary: to understand that prolonged stress causes hormonal changes, increases appetite and relapse risk, and to establish a daily stress-reduction routine that stabilizes metabolism and decision-making.
- Two brief daily stress-reduction practices completed
- At least 7,000 steps per day
- Daily fluid intake target minimally 1.8 liters (2×200 ml in morning, minimally 1 liter during day, 2×200 ml in evening)
- Fixed bedtime and wake time ±30 minutes
- Comfort eating situations recognized in Lifestyle Log
- 10 minutes of quiet walking or breathing exercise during stress
The dual face of cortisol[G]:
- Adaptive function: Cortisol[G] is not an enemy; it helps energy mobilization, regulates inflammation and circadian rhythm[G]. Its short-term elevation (exercise, cold, fasting) is necessary for adaptation.
- Chronic distress: Prolonged psychological stress, however, through HPA axis[G] (hypothalamus[G]–pituitary–adrenal) overactivity, impairs insulin sensitivity[G], increases abdominal fat storage, and generates “hunger noise” (comfort eating compulsion).
Cortisol[G] and low carbohydrate intake:
- Low carbohydrate is not a cortisol[G] stressor: Low carbohydrate diet alone does not elevate cortisol[G] if caloric intake is adequate and the adaptation period is managed. The most common cause of complaints: electrolyte deficiency, sleep deprivation, or too rapid transition.
- Neuroplasticity and metabolic environment: Stable energy supply creates conditions for nervous system adaptation (e.g., BDNF production), but does not replace cognitive activity. This is not in itself a stress management tool, but its context.
Gut–brain axis and stress:
- Stress increases gut permeability[G] and alters microbiota[G] composition – CRH[G] (corticotropin-releasing[G] hormone) acts directly on intestinal mast cells. This sends further inflammatory signals to the brain, impairing mood and self-control.
What do we measure?
- Stress situations and hunger scale correlation (Lifestyle Log).
- Sleep consistency (Fixed bedtime/wake time).
- Effect of recovery routines (breathing exercises, quiet walking) on cravings.
“Stress is a biological signal. The tired brain seeks rapid energy. Rest aids self-control.”
Today you don’t need to change anything – just notice when you feel the urge to comfort eat and record what preceded it.
- Record stress situations in Lifestyle Log
- Use hunger scale during stress
- 10 minutes of slow walking or breathing exercise during the day
- Brief pause every hour during work
- Mental task: when did I eat due to stress? – note 2–3 specific situations: what was the trigger (fatigue? boredom? anxiety?), we’ll return to it tomorrow.
- 5 minutes slow breathing or stretching in the morning
- 30 minutes screen-free in the evening
- 20 minutes easy walking during daylight hours
- Step count at least 7,000
- Mental task: look at yesterday’s list – was there anything common in the triggers? (e.g., always after fatigue? in the evening? during work?) Note it down!
- 10 minutes walking before eating during stress
- Maintain fixed meal times
- Brief relaxation before bed
- Fluid intake: minimally 1.8 liters
- Mental task: when did the craving subside after movement or rest? – and if relapse occurred: identify the trigger, don’t compensate, but continue the routine from the next meal!
- body weight;
- meal times and contents (N–S);
- post-meal walk (Y/N);
- daily protein intake (g);
- energy density[G] (0/+/++);
- NOVA[G] level;
- sleep quality (1–5);
- hunger scale (1–5);
- step count;
- bedtime / wake time (on time, off time);
- Bristol stool (1–7);
- bloating;
- daily bowel movement count;
- fluid intake (l);
- UltraBiome dose;
- LOT identifier;
The goal of these 3 days is to stabilize cortisol[G] rhythm, recognize comfort eating, improve decision-making, and balance the gut–brain axis.
References
[64] Valles-Colomer M, Falony G, Darzi Y et al. The neuroactive potential of the human gut microbiota in quality of life and depression. Nat Microbiol. 2019. Link
Large-scale metagenomics study in the Flemish Gut Flora Project (n=1,054) with replication in independent datasets (total n=1,070) assessing correlations between microbiome features and host quality of life and depression. Butyrate-producing Faecalibacterium and Coprococcus were consistently associated with higher quality-of-life indicators, while Coprococcus and Dialister were depleted in depression independent of antidepressant use. The study provides population-scale evidence for a gut microbiota signature of mental health and depression.