Intermittent fasting could cut weight and delay aging - but there's a problem

Intermittent fasting could unlock lower rates of cancer and obesity as well as cut stress and even make us live longer, new research suggests, but significant hurdles are getting in the way of the diet's advantage. Rather than the typical current diet plan of three meals per day, spread out fairly evenly through daylight hours, intermittent fasting sees people squeeze their meals into just a handful of hours.

It's not a new concept, but it has gained traction in recent years with the rise of so-called "paleo" diets and greater attention paid toward atypical eating routines. At the same time, studies have looked at potential health and lifestyle benefits, focusing on how intermittent fasting can prompt what's known as a metabolic switch, the body shifting from using glucose-based to ketone-based energy.

Usually, those following an intermittent fasting plan would eat within a six hour window each day, and then fast for the remaining 18 hours, though some extend that to as much as 20 hours. The potential benefits from that are more than just around weight loss. According to a new review by Rafael de Cabo, Ph.D., and Mark P. Mattson, Ph.D., of John Hopkins University School of Medicine, "many of the health benefits of intermittent fasting are not simply the result of reduced free-radical production or weight loss."

Benefits of intermittent fasting

According to the review, "intermittent fasting elicits evolutionarily conserved, adaptive cellular responses that are integrated between and within organs in a manner that improves glucose regulation, increases stress resistance, and suppresses inflammation." During periods of fasting, the body's cells would normally shift into processes where damage is removed or repaired, and cellular stress is addressed. However, given the meal cadence of the typical diet, the processes don't have much time to work.

One of the best-known benefits of intermittent fasting is a change in how the body generates its energy. After a meal, glucose from food is used for energy; fat is stored for later use. When fasting, that fat is broken down in turn, with the liver converting fatty aides to ketone bodies.

Those ketone bodies aren't just a sign of fat being broken down, but act as "potent signaling molecules" for our cells and organs. For example, they can influence how proteins, molecules, and genes that influence factors like aging, neurodegenerative disorders, and overall health – among other factors – are produced. Other studies found intermittent fasting could also help improve glucose regulation, manage blood pressure, and cut down on body fat.

The problem with intermittent fasting

While the science may be there, the lifestyle changes for intermittent fasting are a much bigger issue, the study's authors conclude. Perhaps the biggest issue is that we're just not in the habit of abstaining for extended periods of the day.

"First, a diet of three meals with snacks every day is so ingrained in our culture that a change in this eating pattern will rarely be contemplated by patients or doctors," they suggest. "The abundance of food and extensive marketing in developed nations are also major hurdles to be overcome."

There are also barriers to sticking with such a diet, like the inevitable hunger, irritability, and a loss in concentration. That's usually limited to the first month, the researchers point out, but it can be a significant hurdle during that period, and it relies on healthcare professionals making clear that it's a temporary side-effect. Problem is, it's also suggested, physicians themselves often lack the training to give good intermittent fasting advice.

Could a pill replace intermittent fasting?

One other avenue of research, mainly in animal models, has been the hunt for a pharmacologic alternative: a pill that replicates the benefits of intermittent fasting. That has included drugs that impose the same sort of challenge to the body's metabolic system that fasting does, or that specifically triggers the sort of processes that go on during ketosis.

We're still some way from a pill that can do that, however. According to the researchers, "the available data from animal models suggest that the safety and efficacy of such pharmacologic approaches are likely to be inferior to those of intermittent fasting." In short, if you want the best results, you need to stick to the diet.

The best intermittent fasting diet

There are several diet structures that all fall under the umbrella term of "intermittent fasting," and there's no one single perfect meal plan for every person. The most common is probably the daily time-restricted feeding regimen, where you eat within a period of around six hours, and then avoid food for the remaining 18 hours period.

However there's also the 5:2 intermittent-fasting regimen to consider. That limits daily calorific intake to just 500 calories on two days per week, with regular healthy eating on the remaining five days. Whichever structure is picked, there should be a focus on exercise and meal nutrition too.

What intermittent fasting shouldn't be, though, is a sudden blow to the system. That, at the very least, is a recipe for quickly giving up on the diet. Instead, a four month transition period – preferably with regular monitoring of body weight, along with glucose and ketone levels – is recommended, in the hope of making a long-term behavioral change that maximizes the diet's potential benefits to health.