For generations, we've been told it's important to eat "three square meals a day."
Here in the U.S., folks have long believed that you need to have three meals a day – breakfast, lunch, and dinner – to keep your mind and body going. But having three large meals a day wasn't common for all social classes until the 19th century.
Instead, for thousands of years, humans fasted. Our ancestors' nomadic lifestyle of hunting and gathering meant that they sometimes went days without food.
Today, we're not spending our time our time hunting and gathering. In fact, according to a study from the U.S. Centers for Disease Control and Prevention, roughly 80% of Americans don't get enough exercise.
So we need to be eating less. But I'm not saying you need to bother with portion control or rigid measurements... just fast.
Fasting means not eating anything for a set period of time. During a fast, some folks drink water, tea, coffee, or broth.
Short fasts can be for a few hours... In fact, most of us fast every night for many hours while we sleep, before "breaking the fast" with our morning meal. Longer fasts last days or, in some laboratory conditions, even months.
I've long been a fan of intermittent fasting. Fasting very well may be part of the recipe for longevity.
Intermittent fasting involves switching between fasting and eating on a set schedule. But unlike starvation, fasting is a purposeful choice that you can break at any time.
I find fasting makes me feel more in control of my eating and energy. But there are three crucial benefits I want to share with you today...
Three Big Benefits of Fasting
Benefit No. 1: Improves Insulin Sensitivity
When we eat, we take in food and the gut breaks it into usable energy in the form of glucose molecules. Once that glucose gets into our bloodstream, it travels to our cells and keeps them running. The transfer of glucose from blood to cells is facilitated by the hormone insulin.
And one of the benefits of fasting is since there's no glucose from your food, you don't need insulin to create energy. Instead, your body mobilizes its stored fat...
This keeps our insulin levels low. With less insulin, we're in energy-burning mode instead of energy-storing mode. And the longer you stay in that mode, the more fat you burn. Moreover, keeping insulin levels low improves our body's sensitivity to insulin.
The energy from fat becomes molecules are called ketones. And the process of breaking down fat for energy use is called ketosis, which requires no insulin.
In 2019, university researchers from Louisiana, Georgia, and Alabama showed fasting participants had decreased insulin levels before eating, and up to 90 minutes after eating. This means that their insulin sensitivity improved, as they were able to metabolize more glucose with less insulin.
Benefit No. 2: Strengthens Neuroplasticity
When we fast intermittently, we train our brains and bodies to derive energy from fatty acids and ketones – in addition to carbohydrates, glucose, and glycogen. This is called metabolic switching and it happens in two phases – glucose to ketones (Glu-to-Ket) and ketones to glucose (Ket-to-Glu).
When you process new food – carbohydrates, fats, and proteins – your ketone blood levels drop. Ketones start to rise eight to 12 hours after we begin fasting. So when we're eating every few hours, we never get to a point where we're burning fat (and thus ketones). We stop our metabolic switching from kicking in.
Turns out, metabolic switching also impacts the neural connections in your brain (i.e., neuroplasticity). The signaling pathways that are used when the Glu-to-Ket switch happens strengthen our cell resistance to stressors – like infection or toxins – and prepare our cells for the structural and functional change that occurs during a Ket-to-Glu switch.
This directly impacts the areas of our brain where cognition, mood regulation, and motor control take place. For this reason, people with epilepsy (a seizure disorder) are often prescribed a ketogenic diet.
In a 2021 study, Italian researchers from the University of Catania took a look at time-restricted eating in a group of nearly 900 adults – aged 50 and older – living in Sicily. The participants who either skipped breakfast or fasted were less likely to show any cognitive impairments.
For these participants, fasting provided a neuroprotective effect: strengthening neural communication channels. Fasting creates structural improvements in your brain that make it work better for longer.
Benefit No. 3: Increases Cell and Organ Regeneration
And what's more, fasting actually helps with cell and organ regeneration. A study out of Yale University, published last month in Science, examined the effects of a 14% calorie reduction fast in more than 200 participants, over the course of two years.
The researchers used magnetic resonance imaging ("MRI") to look for functional differences in the thymus gland – which produces the immune system's T cells – as the result of fasting. The thymus ages faster than other organs, and typically by age 40, 70% of the thymus is already non-functional.
After two years, the fasting participants were producing more T cells than before and had more functioning volume in their thymus glands. So, fasting allows the thymus gland to rejuvenate.
This partly explains why fasting works well with chemotherapy. As I wrote in my book The Living Cure, fasting deprives your cells – including the cancerous ones – of energy. Healthy cells will slow down to preserve themselves, but cancer cells don't do that. Instead, they burn out and die. (You can buy the Living Cure right here. Or if you're a Retirement Millionaire subscriber, download it free here.)
So give fasting a try. It will only benefit you. And remember, you can choose to break your fast at any time. But by doing what I do – fasting several times a month – you too can enjoy a longer, happier retirement.
What We're Reading...
- Learn more about Hara Hachi Bu here.
- In case you missed it: If you want to lose weight, moving more and eating less might not be enough.
- Something different: How Ikea is breaking into the Indian market.
Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
March 22, 2022