TRE vs Fasting. What Women Need to Know About Skipping Meals.
Time-Restricted Eating vs Fasting: What Women Need to Know Before Skipping Meals
By Jane Marshall. Certified Holistic & Sports Nutritionist, Accredited Holistic Health Coach, Degree Qualified Exercise Physiologist.
You’ve probably heard the terms: intermittent fasting, time-restricted eating, fasting mimicking diets - they're everywhere on socials at the moment. But what do they actually mean? And more importantly, how do they affect women’s bodies, especially during 40s and 50s when hormones, health and energy may feel like a rollercoaster?
I’d like to break it down for you, from a holistic and evidence-based lens, so that you can make an informed choice for yourself. I’ve looked at research from the currently visible NZer: Dr Stacy Sims who argues women are not small men, as well as findings from one of my favourite wells of nutrition research information: the ZOE project led by the work of Prof Tim Spector, Dr Sarah Berry, and Dr Federica Amati.
Fasting versus Time-Restricted Eating: What’s the Difference?
While often used interchangeably, fasting and time-restricted eating (TRE) are not the same.
🔹 Fasting typically refers to extended periods (24+ hours) without food, often done for detox, weight loss, or metabolic reset (Patterson & Sears, 2017).
🔹 Time-Restricted Eating (TRE) is a form of intermittent fasting where you eat all your meals within a specific window each day, often 8–12 hours (Manoogian & Panda, 2017).
The key difference? TRE is daily and rhythmic, whereas fasting can be sporadic and longer in duration.
Do Women Need to Approach Fasting Differently?
Most health trends don’t tell you that biological sex matters. A lot. Especially because most research has historically involved male subjects (Della Torre & Maggi, 2017).
Collating contemporary research findings, they highlight:
Women’s bodies are more sensitive to energy deficits, especially during reproductive years and perimenopause (Sims, 2019; Amati, 2024).
Fasting can disrupt cortisol, thyroid, insulin, and reproductive hormone balance (Trepanowski & Bloomer, 2010; Amati, 2024).
Men show more consistent improvements in fat loss and insulin sensitivity with fasting, but women may see disrupted menstrual cycles, mood shifts, or increased ghrelin (hunger hormone) (Sutton et al., 2018; Sims, 2019).
Dr. Amati stresses the importance of a sex-specific approach, encouraging women to prioritise nourishment, not restriction, and to respect natural hormonal rhythms (Amati, 2024).
TRE & Gut Health: A Surprising Ally
Your gut microbiome loves rhythm—and so does your metabolism. TRE can:
Improve gut microbial diversity by allowing rest periods (Thaiss et al., 2014)
Support gut barrier integrity and reduce inflammation (Zarrinpar et al., 2014)
Synchronise the gut microbiome with circadian rhythms, improving digestion, mood, and metabolic health (Leone et al., 2015)
A 2022 review in Cell Metabolism reported that TRE can reduce gut dysbiosis, especially when paired with a high-fibre, plant-diverse diet (Chaix et al., 2022).
Dr. Amati reinforces this, recommending 30+ different plant foods per week to maintain microbial diversity. She warns that extended fasts or poor refeeding can decrease microbial richness and impair gut motility in women (Amati, 2024).
Hormones, Hunger, and Energy: What to Expect
Benefits of TRE:
Enhances insulin sensitivity and stabilises blood glucose (Sutton et al., 2018)
Encourages visceral fat loss and better mitochondrial function (Longo & Panda, 2016)
Reduces oxidative stress and systemic inflammation (de Cabo & Mattson, 2019)
Improves circadian alignment, leading to better sleep and digestion (Manoogian & Panda, 2017)
Potential downsides for women:
Can elevate cortisol and disrupt thyroid hormones, especially with shorter or erratic eating windows (Trepanowski & Bloomer, 2010)
May increase hunger and emotional reactivity if undernourished (Sims, 2019)
Can affect mood, libido, or cycle regularity (Amati, 2024)
Risk of triggering disordered eating or binge-restrict patterns (Tylka et al., 2014)
Dr. Amati argues that fasting shouldn’t mean starvation—especially for women. Her advice: “Fast from ultra-processed foods, not from meals.” (Amati, 2024). She also emphasises meal timing, fibre, and protein as essential for managing satiety and stress responses.
What Does the Research Say About Safe Eating Windows?
Most modern studies recommend a 10–12 hour eating window (and a 12–14 hour fast) as a safe baseline for women (Chaix et al., 2019).
👉 A 2023 Salk Institute study found that a 10-hour eating window improved sleep, energy levels, and metabolic markers without adverse hunger or stress effects in female participants (Xie et al., 2023).
👉 More aggressive windows like 16:8 or OMAD are often based on male-focused studies and may trigger fatigue, cycle changes, or stress responses in women (Sims, 2019; Amati, 2024).
Dr. Amati suggests aligning eating with the body’s natural circadian rhythm, ideally between 7am and 7pm, and avoiding late-night meals, which disrupt melatonin, insulin, and gut hormones (Amati, 2024).
Who Should Be Cautious with Fasting or TRE?
Fasting or TRE may not be appropriate for:
Women with thyroid conditions (especially hypothyroidism or Hashimoto’s) (Wajner & Maia, 2012)
Those with adrenal fatigue, chronic stress, or sleep disturbances (Trepanowski & Bloomer, 2010)
Individuals with a history of disordered eating (Tylka et al., 2014)
Pregnant, breastfeeding, or trying-to-conceive women (Sims, 2019)
Athletes or very active women with high energy needs (Amati, 2024)
Smart Guidelines for Women Trying TRE
If you’re curious, consider this gentle, science-aligned protocol:
✅ Begin with a 12-hour eating window (e.g., 8am–8pm).
✅ Eat more earlier in the day to support metabolism and reduce night-time cortisol (Jakubowicz et al., 2013).
✅ Include high-protein breakfasts to stabilise blood sugar and reduce cravings (Leidy et al., 2015).
✅ Stay hydrated during fasting hours—herbal teas, electrolytes, water.
✅ Include fibre, protein, and healthy fats in meals to manage appetite (Amati, 2024).
✅ Consider cycling TRE—5 days on, 2 days off—especially during menstruation or high-stress weeks (Sims, 2019).
TRE vs. Fasting: Summary Table
CategoryTime-Restricted Eating (TRE)
Extended Fasting (>24hrs) Duration Daily 8–12 hour eating window24–72 hours (or longer)
Gut Health Supports microbial rhythm (Amati, 2024) Can reduce gut diversity (Zarrinpar et al., 2014)Energy LevelsOften improved with rhythmMay dip, especially in women (Trepanowski & Bloomer, 2010)HormonesGentle if window is balanced (Amati, 2024)Risk of cortisol/thyroid disruption (Sims, 2019)Weight LossGradual, sustainable (Patterson & Sears, 2017)Rapid, but may rebound (Longo & Panda, 2016)Best ForMost women, especially 40+Occasional reset under supervisionCautionsToo short windows may raise stressNot advised for women long-term
Final Thoughts: Your Body Is the Boss
There’s no one-size-fits-all rule here. The best approach is informed, compassionate experimentation—with your body as the guide, not the trend.
If you’re navigating midlife, perimenopause, or simply seeking a sustainable rhythm, Time-Restricted Eating can be a powerful tool—if done with care, nourishment, and hormonal awareness.
As Dr. Federica Amati writes: “The body thrives on consistency, real food, and balance—not restriction, stress, or starvation.” (Every Body Should Know This, 2024).
Want support in finding your rhythm?
Join my Holistic Reset for Women 40+ group or book a 1:1 coaching session. We’ll tailor your nutrition to support your hormones, your gut, and your life.
Key References
Amati, F. (2024). Every Body Should Know This. Ebury Press.
Chaix, A. et al. (2019). Time-restricted eating to prevent and manage chronic metabolic diseases. Cell Metabolism.
de Cabo, R. & Mattson, M. (2019). Effects of intermittent fasting on health. New England Journal of Medicine.
Della Torre, S., & Maggi, A. (2017). Sex differences in metabolism. Nature Reviews Endocrinology.
Leone, V. et al. (2015). Effects of diurnal variation of gut microbes. Cell.
Longo, V.D. & Panda, S. (2016). Fasting, circadian rhythms, and time-restricted feeding. Cell Metabolism.
Manoogian, E.N.C. & Panda, S. (2017). Circadian rhythms, time-restricted feeding, and healthy aging. Ageing Research Reviews.
Patterson, R. & Sears, D. (2017). Metabolic effects of intermittent fasting. Annual Review of Nutrition.
Sims, S. (2019). ROAR: How to Match Your Food and Fitness to Your Unique Female Physiology.
Sutton, E. et al. (2018). Early time-restricted feeding improves insulin sensitivity. Cell Metabolism.
Trepanowski, J.F. & Bloomer, R.J. (2010). Intermittent fasting and the possible benefits in women. Nutrition Journal.
Tylka, T.L. et al. (2014). Mindful eating and disordered eating patterns. Eating Behaviors.
Xie, Z. et al. (2023). Effects of 10-hour TRE on women’s health. Salk Institute Research.
Zarrinpar, A. et al. (2014). Eating patterns and the circadian clock in the gut. Cell Metabolism. life.
