Fasting: The Benefits, Drawbacks & The Science Behind It
Because great results come from understanding what actually works — not following trends.
Fasting has become one of the most talked-about nutrition strategies in recent years, especially for fat loss, energy, and metabolic health. But like any tool, it isn’t magic — and it isn’t for everyone.
Whether you're curious about intermittent fasting, time-restricted eating, 24-hour fasts, or simply tightening your eating window, this blog breaks down the real science, the benefits, the drawbacks, and how to know if it’s right for you.
Let’s dive in.
🔬 What Is Fasting, Really?
Fasting simply means purposefully going for a set period without food.
The most common styles include:
16:8 → fast 16 hours, eat within an 8-hour window
14:10 → a more flexible approach
20:4 (“Warrior diet”) → very narrow eating window
24-hour fasts → done weekly or monthly
Alternate-day fasting → fasting every other day
None are inherently superior.
The best approach is the one you can sustain without harming your energy, training, mood, or relationship with food.
⭐ The Science-Backed Benefits of Fasting
Fasting can have several meaningful physiological effects — some immediate, some gradual. Let’s break them down.
⚖️ 1. It Can Help With Fat Loss (Indirectly)
Fasting itself doesn’t burn fat.
But it can help:
Reduce overall calorie intake (smaller eating window)
Improve appetite control
Lower snacking and emotional eating
Increase awareness of true hunger cues
Think of it as a tool to simplify eating — not a metabolic “hack.”
🔥 2. Improved Insulin Sensitivity
Periods without food allow insulin levels to stabilise, helping your body use stored fuel more effectively.
Better insulin sensitivity supports:
More stable energy
Reduced sugar crashes
Improved long-term metabolic health
This is one of fasting’s most consistent and well-supported benefits.
🧬 3. Autophagy: Your Body’s Natural Clean-Up Mode
Around 12–16 hours into a fast, your body increases autophagy — a process where damaged cells and proteins are repaired or removed.
Potential benefits include:
Improved cellular health
Reduced inflammation
Slower ageing at a cellular level
It’s not a miracle — but it is an impressive biological mechanism.
💧 4. Reduced Inflammation
Research shows fasting may help lower markers of chronic inflammation, contributing to:
Better joint comfort
Improved gut health
Clearer thinking
Faster workout recovery
This is especially helpful for people dealing with stress, soreness, or inflammatory conditions.
🧠 5. Cognitive Benefits & Better Brain Function
Fasting may help increase brain-derived neurotrophic factor (BDNF) — a protein linked to:
Better memory
Improved focus
Reduced brain fog
Enhanced learning
Some people report mental clarity during fasting windows because digestion isn’t pulling as much energy.
🧽 6. Gut Rest & Digestive Ease
Your gastrointestinal system finally gets a break, supporting:
Improved digestion
Reduced bloating
More predictable hunger patterns
Better gut microbiome balance
It’s not a cure-all, but the digestive “quiet time” can be helpful.
❤️ 7. Cardiovascular Improvements
Some research links fasting to:
Reduced blood pressure
Better cholesterol ratios
Lower triglycerides
These benefits often stem from overall calorie reduction and improved metabolic function — not fasting alone.
⚠️ But Fasting Isn’t for Everyone: Drawbacks to Consider
This is where honesty matters.
❌ Energy Dips & Poor Workout Performance
If you train early in the day — especially strength, HIIT or long endurance sessions — fasting can:
Reduce strength output
Increase perceived effort
Decrease performance
Impair recovery
Increase injury risk if under-fuelled
Athletes, active individuals, or anyone training intensely may struggle on an empty stomach.
❌ Overeating in the Eating Window
If hunger gets too high, people often compensate by:
Eating quickly
Overeating
Craving high-calorie foods
Snacking late at night
This erases many of fasting’s potential advantages.
❌ Sleep Disruption
Going to bed hungry or eating too late to "fit food in" can:
Elevate stress hormones
Disrupt sleep
Cause overnight blood sugar fluctuations
Poor sleep = poorer results.
❌ Hormonal Considerations (Especially for Women)
Women — particularly those with:
high training loads
irregular cycles
high stress
low calorie intake
a history of disordered eating
…may experience negative hormonal effects, including cycle disruption or increased stress hormones.
❌ It Can Trigger Unhealthy Food Rules
When fasting becomes rigid, people may experience:
Guilt for eating “too early”
Obsession over hours instead of hunger
Binge–restrict cycles
If fasting worsens your relationship with food, it’s not the right approach.
🧭 So… Should You Fast?
Here’s the honest breakdown:
Fasting might be helpful if you:
✔️ struggle with mindless snacking
✔️ want simpler structure
✔️ prefer fewer meals
✔️ don’t train early in the morning
✔️ have stable energy and a healthy relationship with food
Fasting is not ideal if you:
❌ train hard early in the day
❌ have low energy or poor sleep
❌ feel faint, irritable or foggy when hungry
❌ have a history with restrictive dieting
❌ experience hormonal fluctuations or cycle issues
There’s no “one best diet” — only what works for your lifestyle.
💬 The Takeaway
Fasting is a tool — not a miracle, not a shortcut, and not essential for progress.
It can:
⭐ support fat loss
⭐ improve metabolic health
⭐ reduce inflammation
⭐ support brain and cellular function
⭐ simplify eating
But it can also harm performance, sleep, and relationship with food if misused.
Listen to your body.
Fuel your training.
Choose the approach that supports consistency, not restriction.
💡 Want Support Choosing the Right Approach?
At Coached FITT, we help you build sustainable nutrition habits — fasting or no fasting — based on your goals, lifestyle, and training needs.
👉 Get personalised guidance to fuel your fitness the right way.
👉 Or join our Free Friday Run Club and start your weekends energised.
You don’t need a trend.
You need a plan that works with your life — not against it.