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Forget "dieting" and enjoy your food! What happens each hour while fasting?

Updated: Sep 18

From the last calorie eaten, a simple guide to fasting (please also refer to my fasting strategies guide).

Dan Raynham the fitness scientist: Fasting guide for ultimate health, fitness, extended lifespan and disease prevention.

Unless you have set cultural or religious fasting times, you can fast whenever and however you like. Every day, 2 days per week, once a fortnight or once a month. You can also choose the length of each fast. The results correlate to the amount you do. If in combination with exercise even more so.

I am going to put my head on the chopping block: "In terms of minimal effort for the greatest results, fasting is the only thing anyone should bother with in their eating system. Absolutely massive metabolic and general health benefits! I don't want to create yet another branded "dieting" system. 500 this, catkins that and plate-watchers this blah blah blah. Diets make money. That's all. They are complicated and virtually nobody ever sticks with it, and let's face it, dieting is ####### miserable.

Decide how and when to fast to suit your lifestyle. It will allow you to just enjoy and love food! ...... and possibly more of it! I will give you some basic facts and timings on fasting. Fasting has been understudied in female populations and there are subtle differences. I suggest reading books like Fast like a girl by Dr Mindy Pelz.

Dan Raynham the fitness scientist: Fasting guide for ultimate health, fitness, extended lifespan and disease prevention.
Fitness starts inside you at a molecular level. Your body will thank you for fasting!

If you cannot be bothered with scientific waffle.... fasting directly strips fat, promotes growth, repair and healing, prevents disease and extends lifespan. Aim for a minimum of 14 hours. The sweet spot for minimum effort is probably 16-18 hours. Go for it! Read further for science guff. There is a key to the science terms at the end of the article. Please comment below for links to research papers.

An example of my fasting "day":

Finish eating 8pm


Break-fast next day 1pm

= 18 hour fast.

Then just eat!


4-12 (hours)

Stomach empty.

Blood sugar levels drop.

Insulin production ceases.


Food metabolically absorbed (specifics are activity dependent).

Glucagon lowers to balance blood sugar.

Body 'healing' process starts.

Digestive system torpor.

Human Growth Hormone (HGH) secretion increases.


Body utilises stored fat for energy.

HGH high increase.


Increased fat burning (lipolysis) for energy.


Massive increase in HGH secretion. Possible activation of Heat shock proteins.


Glycogen stores utilised.


Ketones released.


Approximately 300% increase in autophagy.


Immune system reboots.

Inflammation reduction mechanisms increase.

Autophagy 30% increase.


Autophagy at maximum

Dan Raynham the fitness scientist: Fasting guide for ultimate health, fitness, extended lifespan and disease prevention.
Num nums in my tum tums!


HGH: Your bodies amazing natural healing and repair hormone. After your 20s it is at a significantly reduce level. You can raise it massively with high intensity training and fasting. The type of training I do can raises it by 1000's of percent! My body thinks its 18 years old. It burns fat, increases lean muscle mass and improves the health of skin and bone.

Autophagy: Body removes damaged cells and creates new ones. Encoded by the SQSTM1 gene the ubiquitin-binding protein p62 activates to induce autophagy it also improves human lifespan.

Insulin: Let's your body use glucose for energy.

Glucagon: Counteracts the actions of insulin by stimulating hepatic glucose production and fatty acids into bloodstream.

Glycogen: Energy store molecule broken down into glucose when needed.

Ketones: Fatty acid released from liver when glucose is low.

Please contact me directly for media enquiries, academic enquiries, questions and links to research paper's. Thank you! ©️ 2021 Dan Raynham.


Don't fast if you have a history of eating disorders. If you’re pregnant, diabetic or have low blood pressure.

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