The Science of “Fasting Before You Feast”: Why Your Metabolism Needs a Reset Before Thanksgiving
- Dr. Mindy Pelz
- Nov 19, 2025
- 3 min read
The Science of “Fasting Before You Feast”
Every November, I hear women say the same thing:
“Why does one Thanksgiving meal make me so tired, bloated, foggy, or puffy?”
And my answer is always the same:
It’s not the meal.It’s the metabolic state you walk into the meal with.
If your blood sugar is unstable…If your fasting glucose runs high…If your insulin is struggling…If your inflammation bucket is already full…Then even the most joyful holiday foods can hit your body hard.
The solution isn’t restriction.It’s metabolic preparation and fasting is the simplest, most powerful tool we have for that. Let me walk you through the science in a way that makes sense for your female body.
1. Fasting Restores Metabolic Switching
Women feel their best when their metabolism can easily switch between sugar-burning and fat-burning.But constant stress, snacking, poor sleep, and ultra-processed food keep most women “stuck” in sugar-burning mode.
Fasting gently nudges your body back into fat-burning, improving flexibility and making your metabolism more resilient heading into the holidays.
Studies show that fasting increases fat oxidation and improves metabolic switching, helping your body move more efficiently between glucose and ketones.
Why this matters:When your metabolism is flexible, you handle holiday carbs SO much better.
2. Fasting Improves Insulin Sensitivity
Insulin is a fat-storage hormone. It also controls hunger, cravings, energy, and inflammation.
When insulin is high, your holiday meal hits harder and spikes blood sugar more dramatically.
Fasting helps lower insulin and increase insulin sensitivity, which means your cells respond better to food. Intermittent fasting improves insulin signalling and lowers fasting glucose.
Why this matters:Better insulin function = fewer crashes, cravings, or “food comas.”
3. Fasting Activates Autophagy (Your Body’s Cleanup System)
Autophagy is your body’s natural repair mechanism.When autophagy turns on, your cells clear out:
damaged proteins
old mitochondria
inflammatory debris
metabolic waste
You feel clearer, calmer, and more energized.
Autophagy increases significantly during nutrient depletion, helping regulate energy and cellular repair. Autophagy regulates energy balance during nutrient deprivation (PubMed).
Why this matters before Thanksgiving: A body in repair mode is better equipped to handle a rich, celebratory meal.
4. Fasting Lowers Inflammation Before the Feast
If you go into the holidays inflamed, your response to food will be amplified.
Fasting helps calm inflammatory cytokines and supports anti-inflammatory pathways (including ketone production). Intermittent fasting has been shown to reduce systemic inflammation markers.
Why this matters:Lower inflammation = less bloat, better digestion, more stable energy.
Bonus: A Short Walk After the Meal Lowers Blood Sugar
One of my favorite simple hacks. Just 10–15 minutes of post-meal walking improves glucose disposal and reduces spikes. Add this to your Thanksgiving rhythm, and your body will thank you.
So How Do You Put This All Together?
There’s a very specific way to use fasting the week before Thanksgiving to take advantage of these biological benefits — especially for women in perimenopause or postmenopause.
But instead of giving you the entire plan here (it’s too detailed for one post), I created a Free Fast Training Week Companion Guide so you can get the full strategy with cycle adaptations, meal timing, and food suggestions.
Inside, you’ll learn:
how long to fast each day
what to eat before the feast
how to modify based on where you are in your cycle
what NOT to do if you’re feeling stressed, inflamed, or underslept
how to protect your hormones while fasting
It’s completely free — and it will help you walk into Thanksgiving energized, calm, and metabolically prepared.
Final Thought
I never want women to fear food, especially during the holidays. Fasting is not punishment. It’s not deprivation. It’s not about being “good.”
It’s about preparing your metabolism so you can enjoy the food, the people, the celebration, and the moment without the crash later.
Your body is brilliantly designed.When you understand how it works, everything becomes easier.
Research References
Martínez-Rodríguez A, Gil-Gómez J, Rubio-Arias JÁ, et al. Effects of Intermittent Fasting on Body Composition and Clinical Health Markers in Humans: A Systematic Review. Nutrients. 2022;14(5):981. doi:10.3390/nu14050981.
Patterson RE, Laughlin GA, LaCroix AZ, et al. Intermittent Fasting and Human Metabolic Health. Physiol Rev. 2017;97(1):79–117. doi:10.1152/physrev.00036.2016.
Meijer AJ, Codogno P. Autophagy: Regulation and Role in Disease. Cell Death Differ. 2009;16(1):12–20. doi:10.1038/cdd.2008.137.