Fasting has become one of the most talked about health strategies of the last decade. But between the hype, and the before and after photos, it can be hard to know what is actually going on and whether it’s the right strategy for you.

In this blog we will cut through the noise and explain what fasting really does to the body, who it may (and may not) suit, and how to approach it in a way that actually works.

Firstly, it is important to establish that fasting is not a diet. It is not about what you eat. It is about when you eat. At its simplest, fasting means extending the natural overnight gap between your last meal and your first, giving your body more time without incoming fuel.

The most common approach is intermittent fasting, which comes in several forms:

• 12:12: 12 hours fasting, 12 hours eating. This is the gentlest version, and many people already do this without realising it (i.e. you finish dinner at 8pm, you don’t eat breakfast until 8am).

• 16:8: 16 hours fasting, an 8-hour eating window. Popular for weight management and often means skipping breakfast or eating an earlier dinner.

• 5:2: Eating normally for 5 days, then significantly reducing calories (to around 500 to 600 kcal) on 2 non consecutive days.

What fasting is not, is a magic fix. It is a tool - one that can be genuinely useful in the right context, but not one that overrides poor food quality, chronic stress, or a lifestyle that is already running on empty. 

When done properly, fasting can be beneficial for a number of areas of health. These include:

• Weight and body composition - primarily through reducing overall calorie intake and improving fat metabolism.
• Blood sugar control and insulin sensitivity - which is particularly relevant for those with pre-diabetes or metabolic syndrome. Research has shown intermittent fasting to be comparable to continuous calorie restriction for improving these markers.
• Cardiovascular health - with some evidence showing improvements in blood pressure, triglycerides, and LDL cholesterol over time.
• Cognitive clarity - many people report better focus and mental sharpness during fasting periods, likely linked to more stable blood sugar and reduced neuroinflammation.

The key word throughout here is may. Results vary enormously depending on the individual, their approach, sleep quality, stress levels, diet, and hormonal context too. 

Fasting is not universally beneficial, and it is not without side effects, especially in the short term or when it is approached too aggressively. In some people, it may act as a mild hormetic stressor, meaning a controlled challenge that can prompt adaptive responses. But that same stress can become counterproductive when someone is already under a lot of physiological or emotional strain.

That is why, whenever I am asked about fasting at public talks, my answer is always: “it depends.” It depends on the individual, their health circumstances, their stress load, and whether fasting is truly the right tool at that time.

Common side effects can include fatigue, headaches, poor concentration, irritability and disrupted sleep, particularly during the initial adaptation period. More significant concerns include nutrient deficiency if the eating window becomes too narrow or food quality is poor, and overcompensating during the eating window, which can undermine the intended benefits.

Fasting is not suitable for everyone. It should be avoided, or only undertaken with medical supervision, by pregnant or breastfeeding women, anyone with a history of disordered eating, people with type 1 diabetes or those taking blood sugar-lowering medication, anyone with significant thyroid concerns, and children and adolescents. For people who are already highly stressed, strict fasting may not be the best place to start, even if the theory sounds appealing.

If you are curious about fasting, here is how to approach it in a way that supports your body rather than stresses it.

• Start small: A 12 to 14 hour fast is a meaningful and manageable starting point. You do not need to jump straight to 16:8, and you certainly do not need to fast every day. Less is often more, particularly if your nervous system is already under pressure.
• Prioritise what is in your eating window: Fasting only works well when the food you eat within your eating window truly nourishes you. Aim for adequate protein at every meal (25 to 35g per sitting), plenty of fibre-rich vegetables, healthy fats, and micronutrient-dense whole foods. Fasting should never become a reason to eat less well.
• Time it wisely: If you are going to try a longer fast, earlier in the day tends to suit women better than late eating windows. Eating the majority of your food earlier and closing the window by early evening aligns better with female circadian and hormonal rhythms.
• Tune into your biofeedback: Your body will tell you whether fasting suits you if you are paying attention. Signs it is working well include stable energy, good sleep, clear thinking, and consistent mood. Signs to pull back include worsening PMS, disrupted sleep, brain fog, heightened anxiety, or feeling noticeably worse on fasting days.
• Do not fast when already depleted: If you are going through a period of high pressure - physically, emotionally or professionally - this is not the moment to add fasting as an additional stressor. Prioritise nourishment and nervous system recovery first.

Used strategically, the right supplements can make fasting more comfortable and sustainable.

During the fasting window, hydration is a priority. Because fasting can increase sodium and water loss, some people notice headaches, fatigue, dizziness, or brain fog, and staying on top of fluids and electrolytes can make the fasting window feel more manageable. That is where products like Extracted’s Hydree may fit in as part of a hydration routine.

Within the eating window, the focus shifts to recovery and replenishment. If you are training fasted or placing regular load on your joints, collagen support such as Extracted’s Reeplay may be a useful addition alongside adequate protein and nutrient-dense meals if needed. For anyone with joint or mobility concerns, Flexee offers a more targeted option that may be helpful when training and eating windows do not always align neatly.

Sleep is another important factor to watch. For some people, fasting, especially when eating windows run later into the evening or become too restrictive, may affect sleep quality and sleep timing. If you notice that sleep is being disrupted, Sleepee may help support a calmer evening routine and natural sleep onset alongside ensuring your dietary intake and wind down routine are in place. This matters because good sleep is closely linked to metabolic health, and when sleep suffers, the overall benefits of fasting may be harder to realise.

Fasting can be a genuinely effective tool when it is the right fit, implemented thoughtfully, and properly supported. But it is not a shortcut, and it is not for everyone. The best approach is the one that works with your energy, your hormones, and your life rather than against them.