Starving the Gut Feeds the Brain

If our bodies could speak to our brains, many would hear this: “Dear brain, please know the difference between being hungry and bored. Sincerely, I’m getting fat!” Who doesn’t turn to food when the doldrums set in?

The smart brains would offer their hosts three pieces of advice. One, eat nutritional food. Two, limit portion sizes. And three, now and again, engage in fasting. Why fasting? Because studies show that for obese and skinny people alike, after prolonged reduction of food intake, the body’s defences improve against stresses. Cardiovascular risks decline. And the brain functions better.

Temporary cessation of eating provokes chemical changes throughout the body. Ketones are a type of chemical the liver produces when it breaks down fats. The body puts ketones to work as a source of energy when food sources are absent. Ketones are also active during extended exercise or when carbohydrates are not available. Production kicks into gear during a fast.

One of the consequences is an increase in the activity of helper molecules that ease the work of neurons to connect with neighbouring neurons. Brains and the nervous system depend on these cells connecting with each other to function and reproduce effectively.

Interestingly, an increase in the production of ketones also reduces appetite, a helpful effect in maintaining a fast. This is why people who make it past an initial bout of hunger without eating will find the sensation of hunger diminishes.

Need more motivation? Research at Johns Hopkins University School of Medicine has demonstrated that sedentary lifestyles involving easy access to food indulgences accelerate the aging of the brain. In such people, scientists have identified telltale signs of problems that leave the brain vulnerable to Alzheimer’s and Parkinson’s diseases and stroke. The labels describing these markers tell the story: “stem cell exhaustion”, “aberrant neuronal network activity”, “oxidative damage”, “impaired molecular waste disposal”, and “mitochondrial dysfunction”, to name a few.

Studies have also started to explore how the timing of food intake affects obesity and measures to achieve weight loss. Normal eating patterns involve a striking a balance between the rewards of food intake and the regulation of energy. Our bodies are well adapted to modest, regular meals. But modern lifestyles make eating frequent calorie-rich foods easy. This launches the brain-gut microbiome into reward overdrive, depriving the system of the opportunity to shift into time for regulation of energy. Weight gain is among the consequences.

This helps explain the success of diets involving time-restricted eating, the practice of consuming no calories outside of established hours.

What qualifies as fasting? The answer ranges widely. Most people will be familiar with the doctor’s orders for a 12 or 24 hour fast before certain medical tests or procedures. But for weight loss, and to gain the benefits for brain and cardiovascular health, longer periods of intermittent fasting are required.

The key to success is moderation. Fasting need not be an unpleasant pursuit. To the contrary, implementing a habit of reduced food consumption can have its own rewards. Extra body fat will be reduced. The brain will age more slowly. The heart will be healthier. And researchers have found mood improvements, even euphoria, associated with fasting.

The next time your stomach hollers “feed me”, let your brain do the work. “Listen to me,” it will say. “I need a few hours to think this over.” Have a glass of refreshing water, then focus on other activities. Step on your bathroom scale every morning to see the results and keep this article in your pocket to remind yourself of the benefits of intermittent fasting.

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