Should You Be Fasting? What the Science and Your Body Might Be Telling You

2 Aug

If there’s one topic that consistently comes up — whether I’m speaking at events, presenting to organisations, or sitting on a panel — it’s fasting.
“Should I be fasting?”
“What do you think about intermittent fasting?”
“Is fasting really good for you?”

They’re great questions. And they reflect the very modern collision between ancient traditions and contemporary health culture.

Fasting has been practiced for thousands of years — some of the earliest recorded fasts date back to ancient Greece and India, where abstaining from food was tied to spirituality, clarity, discipline, and connection. Today, though, fasting has moved beyond its traditional roots and into the realm of diet culture. From biohacking blogs to Instagram reels, we’re told that fasting will boost longevity, burn fat, and regulate our metabolism — often without much nuance.

So what’s the truth? Should we be fasting — and if so, how much, how often, and why?

Let’s unpack the science, the context, and the human reality.

The Science of Fasting: Fed vs Fasted State Metabolism

To understand fasting — and why it might be beneficial — it helps to revisit how the body works.

When we eat, we enter what’s known as the fed state. Our blood glucose rises, insulin is released, and our body shifts into energy storage mode. This is entirely normal and necessary — we need fuel to live. But when we’re constantly grazing, snacking, or eating from early morning until late evening, our metabolism rarely gets a break.

In contrast, the fasted state is where the body taps into stored energy, switches fuel sources (from glucose to fat), and engages in important cellular processes like autophagy — the cleanup and recycling of damaged cells.

In modern society, with food available 24/7, we tend to spend most of our time in the fed state. We’re locked into eating patterns that don’t always align with how our bodies evolved. Fasting — done thoughtfully — can help restore some of that natural rhythm.

We Are Designed to Fast — But That Doesn’t Mean More Is Better

One of the things I say a lot, in clinic and beyond, is this:
Rarely in the world of nutrition does “more” equal “better.”

It’s very easy to fall into a belief system where something is “good” — fasting, olive oil, avocados — so more must be even better. But the reality is, balance and moderation are always key. Too much fasting, especially without context, can be just as disruptive as not enough nourishment.

We have to step back and ask: Why are we doing this? Is it coming from a place of curiosity, self-respect, and health? Or from a place of control, anxiety, and perfectionism?

The Beauty of Traditional Fasting

I’m a big fan of traditional, spiritual, and cultural fasting. These fasts often take place in a community setting, with structure, meaning, and purpose. They are life-affirming, not fear-based.

Interestingly, research shows that the health benefits of fasting may be amplified when it’s connected to a sense of spiritual purpose and community participation. A 2020 study published in Nutrients found that Ramadan fasting, when paired with mindful eating and cultural rituals, can lead to improvements in blood sugar regulation and cholesterol markers — all without triggering the psychological burden often associated with diet-focused fasting.

When fasting is about connection rather than control, it takes on a very different tone. It becomes peaceful, not punishing.

Physiological and Biochemical Individuality: Fasting Isn’t One-Size-Fits-All

Not everyone responds to fasting in the same way — and that’s important.

We all have unique genetics and biochemical individuality that influence how we metabolise food, how long we can comfortably go without eating, and how we respond to metabolic stress. Some people genuinely thrive with longer gaps between meals. Others may feel irritable, fatigued, or sluggish.

Women, in particular, may experience very different fasting tolerances depending on where they are in their menstrual cycle, life stage, or stress levels. For example, in the luteal phase (the second half of the cycle), increased energy demands may mean that long fasting windows feel less supportive. Similarly, in perimenopause or postmenopause, hormonal shifts can affect how the body responds to fasting entirely.

This is why rigid, daily fasting protocols — like a 16:8 fast done religiously every day — can be problematic. Our needs change. Life changes. Fasting can be a tool for self-awareness, not a rule to live by.

Circadian Rhythms and the Work of Dr Satchin Panda

One of the researchers whose work I deeply respect is Dr Satchin Panda, a leading expert in the field of circadian biology. His studies, particularly those at the Salk Institute, have shown that when we eat matters just as much as what we eat.

His research on time-restricted eating (TRE) demonstrates that eating within a 10- to 12-hour window aligned with our circadian rhythms (daylight and darkness) can support weight management, metabolic health, and even improve sleep. In one study published in Cell Metabolism (2015), mice fed within a set window avoided weight gain and metabolic disease — even when consuming the same number of calories as mice who ate around the clock.

While many of Dr Panda’s foundational experiments began with mice, human trials are already confirming promising effects of TRE. For example, a randomised trial of 108 adults with metabolic syndrome using an 8–10  hour eating window showed 3–4% body fat reduction, improved blood sugar and lipid markers — all with preserved lean mass, and without deliberate calorie restriction (TIMET trial, 2024) .

This doesn’t mean we all need to fast until noon — but it does invite us to think more consciously about meal timing. Are we eating late into the night? Are we giving our digestion time to rest?

A Gentle Starting Point: The 12-Hour Overnight Fast

For most people, a simple 12-hour overnight fast is a safe, sustainable place to begin. That might mean finishing dinner by 7:30pm and having breakfast at 7:30am. It’s not extreme. It doesn’t require skipping meals. But it gives your digestive system — and your metabolism — a little breathing room.

From there, you might experiment with:

A 14-hour fast a couple of days a week,
Leaving 4 hours between meals without snacks,
Tuning into how hunger and energy feel when you’re not always eating “just in case.”

It’s less about rigid rules and more about gentle experimentation.

When Fasting Might Not Be Helpful

There are some circumstances where fasting is not appropriate — and it’s important to name these clearly:

History of eating disorders: Fasting can re-trigger restrictive behaviours or binge-restrict cycles.
Hypothyroidism or thyroid dysfunction: Some people with underactive thyroids may feel worse with prolonged fasting, particularly if adrenal health is also compromised.
Pregnancy or breastfeeding: Additional nutrients and more frequent meals are often needed.
High stress or burnout: Cortisol dysregulation can make fasting feel depleting, not restorative.

If you’re unsure, speak to a practitioner who understands the full picture of your health, not just your weight or goals.

Fasting Is a Tool — Not a Moral Obligation

On balance, I am a fan of fasting — when used wisely. I don’t believe it should be a moral imperative or a badge of honour. And it certainly shouldn’t be used to punish or restrict the body.

We can use fasting as a way to engage with our bodies, learn from them, and observe how we feel with different rhythms. But always remember: you don’t earn your health by how long you go without food. You build it by staying connected to what nourishes you — physically, emotionally, and spiritually.

Key Takeaways

Fasting has ancient roots — but modern forms must be approached with nuance.
The fed and fasted states are both important. Overeating and over-fasting can both be unhelpful.
A 12-hour overnight fast is a safe and sensible starting point for many.
Not everyone is biologically or emotionally suited to fasting — especially women, depending on their cycle, life stage, and stress load.
It’s not just about when you eat — it’s about what you eat during your eating window, too.
As always, more isn’t always better. And health isn’t found in rigidity, but in rhythm.

Experience Fasting in a Peaceful, Supported Way – This September

If this article has sparked your curiosity about fasting done gently and intentionally, I’m thrilled to share that I’ll be offering nutrition support at the beautiful Wild View Retreat in Portugal between 6th and 13th September, 2025.

Set in the stunning Algarve hills, this retreat offers more than just a break from food — it’s a chance to reset, reconnect with your body, and experience fasting as it was always meant to be: peaceful, nurturing, and spiritually grounded.

🌿 This is one of the most supportive environments I’ve ever seen for fasting — a rare chance to step away from the noise and into rest, reflection, and care.

If you're interested in joining or learning more, click here to view the retreat and book your place.
Or, if you'd like to chat with me first to see if it’s the right fit for you, feel free to get in touch here.