Fasting is linked to enormous benefits, but also serious risks

A clear understanding of our body’s response to dieting and fasting has been an intriguing topic for researchers in the field of health and science for many years.

At the Massachusetts Institute of Technology, researchers are shedding new light on the complex mechanisms involved in our body’s reaction to fasting and low-calorie diets.

The research has been focused on the regenerative abilities of our intestinal stem cells, and how fasting can boost their ability to recover from injuries or inflammation.

How fasting works

It’s no news that intermittent fasting and low-calorie diets come with health perks. From delaying age-related diseases to lengthening lifespan, the benefits are not just limited to humans – they extend to many other organisms as well. But, how does this entire phenomenon work?

Intermittent fasting boosts the regenerative skills of intestinal stem cells. These cells play a crucial role in assisting the intestine in bouncing back from injuries or inflammation.

As our little mice friends began refeeding after their fasting period, the researchers discovered a pathway that sparked enhanced regeneration.

A bit of caution, though – it’s not all rosy! If any cancerous mutations happen during this regenerative period, our rodents showed a tendency to develop early-stage intestinal tumors.

“Having more stem cell activity is good for regeneration, but too much of a good thing over time can have less favorable consequences,” said Omer Yilmaz, an MIT associate professor of biology, and a member of the Koch Institute for Integrative Cancer Research.

Fasting-feeding roller coaster

Yilmaz’s team has been sleuthing about for years to understand how fasting and low-calorie diets impact intestinal health.

Back in 2018, the team revealed that during a fast, intestinal stem cells switch their energy source from carbohydrates to lipids. This change revs up their regenerative abilities like a supercharged engine.

But a lingering question remained – how exactly does fasting trigger this regenerative boost? Was it the fasting itself or the post-fast eating that was the real game-changer?

When the clock strikes “refeed”

The MIT researchers found that stem cell regeneration slows down during fasting but hit the accelerator once refeeding begins.

Three groups of mice were taken under the spyglass for this study. One group fasted for 24 hours, another fasted for 24 hours and then munched away freely during a 24-hour refeeding period, while a control group kept its eating habits steady throughout the experiment.

The stem cells displayed a proliferation party at the end of the refeeding period. These festive cells were more active than those in the mice that hadn’t fasted at all.

“We think that fasting and refeeding represent two distinct states,” noted the researchers.

Nutrient-regeneration connection in fasting

The mTOR pathway, involved in cell growth and metabolism, turns on like a bright guiding signal during the refeeding period.

With this highway open, the cells begin to produce more proteins, a critical ingredient for stem cells to multiply.

It’s like those stem cells are flexing their muscles, pumping up in preparation to repopulate the intestinal lining.

The risks of fasting

As discussed before, every coin has two sides. While the enhanced stem cell activity gives a boost to regeneration, these overachieving cells are more prone to becoming cancerous.

The intestinal stem cells are among the busiest in the body, continuously replacing the lining of the intestine. This frequent cell division makes them a common source of precancerous cells in the intestine.

So, what’s the bottom line? Fasting can be helpful, but if you’re unlucky and have a hearty, let’s say, charred steak, after your fasting, you might be inadvertently boosting your risk of developing a lesion that could lead to cancer.

“I want to emphasize that this was all done in mice, using very well-defined cancer mutations. In humans it’s going to be a much more complex state,” said Yilmaz.

Looking ahead

The regenerative benefits of fasting could be significant for people undergoing treatments that can damage the intestinal lining, like radiation, or those suffering from other types of intestinal injuries.

Yilmaz’s lab is now exploring if polyamine supplements could kindle this kind of regeneration, sans the need to fast.

To fast or not to fast

The jury’s still out on that one. More research is needed to paint a clearer picture of the role of fasting in human health, including the potential risks. Until then, the best approach to dieting or fasting is a balanced one.

Remember, it’s not just about what you eat or don’t eat. It’s about understanding the impact of these choices on your overall health.

The study is published in the journal Nature.

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