In 2019, Stephanie Buttermore, a biomedical researcher and fitness YouTuber, started her "All In" challenge: eating intuitively without restriction after years of careful macronutrient tracking and caloric control. The results were striking — she gained weight but also gained muscle, improved her menstrual cycle, increased her energy, and appeared healthier overall.
Her transformation became a case study in reverse dieting, metabolic adaptation, and female hormonal health. It also sparked debate: was she just eating in a caloric surplus and gaining fat? Was her experience unique to her context? What does the science actually support?
This guide breaks down what Buttermore's journey tells us about intuitive eating, body recomposition, and female metabolic health — and where the science aligns with her experience.
The Context: Red-S and Metabolic Adaptation
Before diving into what happened during Buttermore's All In phase, understand the antecedent.
Buttermore had spent years in caloric deficits, training hard, and tracking macros meticulously. This produced excellent short-term body composition results: very low body fat, visible muscle definition. But it came with costs.
RED-S (Relative Energy Deficiency in Sport): When energy availability (calories minus exercise energy expenditure) is too low relative to physiological demands, the body down-regulates metabolic processes. This includes:
- Decreased resting metabolic rate
- Hormonal disruption (low oestrogen, irregular or absent menstrual cycles)
- Reduced bone density
- Decreased immune function
- Impaired recovery from training
- Mood disturbances and cognitive effects
Buttermore's restricted eating and training created a state of relative energy deficiency. Her menstrual cycle had stopped (amenorrhoea). Her energy was low. Her body composition was excellent, but her health metrics were compromised.
This is important context: Her All In journey wasn't just "eating more" — it was recovery from a long-term energy deficit state.
The All In Phase: What Actually Happened
Buttermore began eating intuitively without caloric restrictions. She ate when hungry, stopped when full, and didn't track macros. Her caloric intake increased substantially — research on intuitive eating suggests this typically increases intake by 300-500kcal daily compared to prior restriction.
The results over several months:
- Weight increased by roughly 5-8kg
- Menstrual cycle returned (a clear sign of restored energy availability)
- Body composition changed: some fat gain, but also apparent muscle gain
- Energy levels improved significantly
- Recovery from training improved
- Mood stabilised
The Science Behind the Changes
1. Metabolic Restoration
Years of caloric deficit causes metabolic adaptation: your body down-regulates energy expenditure. When restriction ends and calories increase, metabolic rate doesn't immediately spike back up — but it does improve substantially.
Rosenbaum et al. (2008) found that metabolic adaptation persists even after weight loss ends, but it partially reverses with increased energy intake. Buttermore's metabolic rate probably increased 10-15% as she shifted from deficit to surplus, explaining some of her weight gain.
2. Hormonal Restoration
Low energy availability suppresses reproductive hormones. When energy availability improves:
- Leptin increases
- FSH and LH increase
- Oestrogen increases
- Thyroid hormones normalise
These hormonal changes drive the return of menstruation and improve recovery from training. Buttermore's restored cycle was a direct result of restored energy availability.
Clinical note: Loucks & Thuma (2003) demonstrated that energy availability below 30kcal per kg lean mass causes suppression of luteinizing hormone pulsatility (critical for menstruation). Restoration of energy availability reverses this.
3. Body Recomposition Mechanics
Buttermore gained weight but her body composition improved — she appeared to gain muscle while also gaining some fat. How?
Mechanism 1: Protein Synthesis Recovery
Caloric deficit suppresses muscle protein synthesis. Adequate protein intake in a surplus restores it. Buttermore trained consistently throughout, so increased stimulus + improved hormonal environment + adequate protein = muscle gain.
Mechanism 2: Glycogen Repletion
After years of restriction, her muscles were glycogen-depleted. Increasing carbohydrate intake repletes muscle glycogen (which holds water). This accounts for some weight gain but also improves training performance and recovery.
Mechanism 3: Genuine Fat Gain
She also gained fat. Eating in a caloric surplus and switching from deficit to surplus causes fat gain. This isn't failure — it's expected. The question is the ratio of muscle to fat gained.
The ratio: Buttermore appeared to gain roughly 1-2kg of muscle and 3-4kg of fat (visual estimate based on before/after footage; no DEXA scan data was publicly available). This is a reasonable ratio for a return to surplus after prolonged deficit, particularly given her training consistency and adequate protein intake.
Progressive Overload and Female Muscle Gain
One understated aspect of Buttermore's transformation: her training improved. With restored energy and hormones, she lifted heavier, trained more consistently, and achieved better progressive overload.
Why this matters: Muscle is built through progressive overload. The stimulus (training) was always there. What changed was recovery capacity and energy availability, allowing stimulus to translate into adaptation.
For natural female athletes, this principle is critical. You can't build muscle in a severe deficit. You need adequate energy availability, adequate protein, and consistent progressive overload.
The Intuitive Eating Question
Buttermore used intuitive eating — eating when hungry, stopping when full, no macro tracking. Did this approach matter, or did the results come from simply eating more?
What the research says:
Intuitive eating in individuals without restriction history can produce reasonable results because hunger cues are generally reliable. However, after prolonged restriction, hunger cues are often dysregulated. Buttermore's hunger cues normalized as energy availability improved — a common observation in eating disorder recovery.
The practical takeaway: For most women, especially those coming out of restriction, some structure (tracking calories or macros) is useful initially. Once metabolic markers normalise (menstrual cycle, energy, strength), more flexibility is possible.
Pure intuitive eating without history of restriction probably produces reasonable results in some people. After restriction, it's riskier — you might overcorrect significantly (which Buttermore appeared to do initially) or undercorrect (not restoring enough to fix the underlying deficiency).
What Buttermore's Experience Reveals About Female Athletes
1. Menstruation as a Health Marker
Buttermore's restored menstrual cycle wasn't cosmetic — it was a sign of restored reproductive health and improved overall metabolic health. Female athletes should take amenorrhoea seriously. It indicates energy deficiency requiring intervention.
2. The Cost of Extreme Leanness
Very low body fat in women (sub-15%) suppresses reproductive hormones more than in men. This is physiologically normal but comes with costs (bone density, hormonal health, metabolic function). For non-competing athletes, 18-24% body fat is likely healthier long-term.
3. Strength Training Changes With Hormonal Restoration
As Buttermore's oestrogen restored, her training likely improved. Higher oestrogen correlates with improved recovery and performance. Female athletes shouldn't expect identical training performance across the menstrual cycle — this variation is normal and should inform programming.
The Broader Implications: Female Body Recomposition
Buttermore's journey illustrates female body recomposition principles:
Body recomposition: Building muscle and losing fat simultaneously. Possible in:
- Individuals returning from restriction (like Buttermore)
- Beginners to training (elevated MPS with any training stimulus)
- Individuals with significant pharmaceutical support
For natural female athletes: Expect 0.25-0.5kg monthly lean mass gain in the best case, alongside some fat gain in a surplus. The ratio improves with adequate protein, consistent training, and progressive overload.
Practical Application: Female Athletes Learning From Buttermore
If you've been in restriction:
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Restore energy gradually: A jump from 1800kcal to 2500kcal daily might be too fast. Increase by 200-300kcal per week, monitoring hunger, energy, and mood.
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Track initially: Intuitive eating after restriction is risky. Track calories for 4-8 weeks to understand your true intake, then adjust.
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Monitor menstruation: Return of regular cycles indicates successful restoration. If amenorrhoea persists beyond 2-3 months of increased intake, investigate further.
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Expect some fat gain: Transitioning to surplus causes fat gain. This is normal and necessary for hormonal recovery.
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Maintain training consistency: Progressive overload remains critical. As energy improves, your training should also improve.
If you're starting from average body fat (18-25%):
Body recomposition is slower than Buttermore's restoration. Expect:
- 0.25-0.5kg monthly lean mass gain in surplus
- 0.25-0.5kg monthly fat loss if you reduce intake slightly
- 0-0.25kg monthly lean mass gain with maintenance calories
The approach depends on your goal. Prioritise muscle: eat in slight surplus. Prioritise fat loss: eat in slight deficit.
The Psychological Shift
Part of Buttermore's transformation was psychological. Years of restriction create food anxiety, body image distortion, and training obsession. Shifting to intuitive eating reduced anxiety and improved mental health.
This matters. For many female athletes, the psychological cost of restriction exceeds the physical benefit. Buttermore's experience shows that health — physical and mental — improved simultaneously with refeeding.
Where Buttermore's Experience Might Not Generalise
Individual factors:
- Her training age (10+ years) and consistency allowed rapid muscle gain
- Her genetics are above-average
- Her discipline allowed controlled progression despite intuitive eating
- Her context (biomedical researcher, educated about nutrition) supported good decision-making
Others might:
- Gain more fat, less muscle in a similar surplus
- Overshoot in intuitive eating and gain excessive fat
- Have more difficult menstrual cycle recovery
- Face different hormonal or metabolic baselines
Her story is instructive but not universal.
The Bottom Line
Stephanie Buttermore's All In journey illustrates several evidence-based principles:
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Severe energy deficiency causes hormonal disruption and metabolic adaptation. This applies to female and male athletes.
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Restoration of energy availability reverses many of these effects. Menstruation returns, metabolic rate improves, recovery enhances.
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Body recomposition is possible when returning from restriction, because the stimulus was always there — recovery capacity was the limiting factor.
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Intuitive eating can work but requires metabolic normalisation first. Initial tracking often helps.
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Female athletes should monitor menstrual health as a proxy for overall metabolic health. Amenorrhoea is a sign to increase energy intake.
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Some fat gain is necessary and healthy when restoring from restriction.
For female athletes, this means: don't chase extreme leanness long-term. Maintain 18-24% body fat with consistent training and adequate nutrition. This is healthier, more sustainable, and supports better training performance and body composition long-term.
Recommended Resources
Nutrition & Tracking:
Training for Women & Supplements:
Further Reading:
- Female Athlete RED-S: Recognition and Recovery
- Body Recomposition for Women
- Menstrual Cycle and Training Performance
- Reverse Dieting: A Practical Guide
- Intuitive Eating vs Tracking: When Each Works
About the Author
Seb writes about evidence-based training and nutrition for female athletes at LiftLab. He appreciates Buttermore's transparency about her journey and the useful data it provides about female metabolic health and body recomposition.