The most obvious solution to losing weight is to stop eating and obesity is one of the most deadly diseases. Yet so few people would ever consider fasting for losing weight. People across all cultures fear not eating which is very odd humans evolved to survive without regular access to food and fasting is recommended by the all the great world religions. Fasting is easy. Literally anyone obese can do it and it does not require any medication, trainers, restriction of activities, shopping, cooking and cleaning. To the contrary, fasting will save time and money.
Humans are built to fast, they’ve chosen fating to make themselves healthier for thousands of years and they will save substantial amounts of time and money. So it’s very odd that we have come to fear it when it’s needed more than ever.
On one hand it’s obvious how fasting works. A person doesn’t consume any calories, their body burns fat which leads to weight loss. But why doesn’t consuming less calories work? The same logic applies but millions of earnest people have failed to lose weight using that strategy. The devil is in the details. Fasting used to be imposed on humans by nature. Vegetables and fruit aren’t always available in all places and successful hunts are sporadic by nature. We are adapted for feast and famine cycles. It’s why we so easily put on fat.
The human hormone insulin drives fat storage. High insulin levels stores fat and blocks the conversion of fat stores to energy. This fact apparent when insulin is artificially increased in diabetics and fat storage increases even under the most restrictive of diets. The relationship is so tight, fat accumulation appears right in the area where insulin is injected. When humans stop eating for a couple days and they body has figured out it’s not eating anymore, insulin levels drop and it stays low. The body stops storing fat and actively converts fat into ketones and glucose. Essentially, human fat stores are turned into water and carbon dioxide. When it comes to weight loss, that’s it. Reducing calories does not work because insulin levels stay high when we eat numerous small meals. High insulin levels blocks the body’s access to fat - even when there’s limited caloric intake to support regular activities. So when a person is on reduced calorie diet, they do not have access to calories in their fat stores. Their metabolism adapts by ramping down and decreasing the amount of energy available for daily activity. The dieter becomes tired and irritable. They may still lose weight but at a much slower rate than simply by fasting and a higher proportion will come from the break down of muscle.
Fasting, on the other hand, opens up vast caloric reserves for the body to use. Metabolism will remain high, facilitating weight loss and the faster will experience only limited changes in their mood. Their daily activity will not be impacted. The brain prefers ketones as an energy source and the liver is able to easily convert ketones to glucose for muscles. Hunger is also not a problem because the hunger hormone ghrelin also drops and stays low when fasting whereas it stays high on a calorie deficit and the dieter lives daily starvation.
Autophagy is another benefit of fasting. The energy expended in digestive can be redirected towards cellular repair. When insulin declines, glucagon increase and stimulates autophagic processes. At the same time, fasting also increases growth hormone which stimulates the creation of new cells.
So fasting and calorie deficit dieting seem like they should be equally effective until we look at what is happening at the hormonal level inside the human body. When we take into account hormones, fasting is vastly superior to dieting.
The hardest thing about fasting is the social alienation. Fasting was societally regulated in religious societies. In Christian societies, intermittent fasting was required on for the 40 days of Lent, Ash Wednesday and Good Friday for most denominations. Muslins fast during Ramadan and Buddhist fast during periods of extended mediation. Fasts were balanced by societal feasts. Everyone fasted and feasted at the same time.
In modern life, there are only feasting seasons like Thanksgiving and Christmas. Fasting is done alone and the practice itself comes off as judgemental and/or abhorrent. Fasting also opens up a lot of time and humans like to think about food when they are bored, whether or not they are fasting, but it makes fasting seem extra difficult. Ideally, fasting takes place during a busy time during the year when it is easy to forget to eat. Fasting should also be balanced with feasting to rejuvenate social relationships, replenish exotic nutrients and build new cells.
