Here’s What They Know about Intermittent Fasting

The dirty and unspoken truth is that diets don’t result in long-term weight loss, so research must focus on obesity as a metabolic disease with a cure and stop viewing it as a moral failing.

Scientists studying obesity are finally shifting their focus from overly simplistic calorie in/calorie out experiments to studying the possible metabolic causes of obesity. As part of this research, studies have shown that fasting may play a roll in helping to “flip” the metaphorical metabolic switch in obese people. Here’s what they know so far.

Clinical studies on long-term fasting, defined as six months or more, have shown to induce weight loss and reduce cardiovascular risk factors, insulin sensitivity and mitochondrial function. The downside? Almost no one can maintain long-term fasting. And frankly, why would anyone want to? Eating is more than just a physical necessity after all.

But that doesn’t mean studies on fasting have no value. Even the dumbest among us know that starving yourself (essentially) will lead to weight loss and that almost no one has the superhuman strength to maintain this draconian lifestyle for any length of time. Worse, long periods of deprivation almost always leads to weight gain again and may actually harm metabolic systems that researchers don’t know enough about. The good news is that researchers did find that there are benefits to intermittent fasting, or periods defined as 12 hours or longer. Intermittent fasting has also been shown to improve cardiometabolic health and result in weight loss. But first, what exactly is cardiometabolic health?

Cardiometabolic is a relatively new term that includes both cardiovascular and metabolic diseases, including type 2 diabetes and metabolic syndrome. Metabolic syndrome, or basically metabolic dysfunction, is characterized by insulin resistance and impaired glucose tolerance, high cholesterol, high blood pressure and excess abdominal fat.

The unintended takeaway I get from intermittent fasting research and those studying cardiometabolic health is that science has finally moved beyond the absurd calories in/calories out as the sole cause of obesity and is recognizing and focusing instead on the metabolic and cellular components of obesity, which I explored in length in my articles Why Are You So Fat? and Sugar Feeds Cancer.

By recognizing that there are underlining mitochondrial dysfunction in obese people, perhaps scientists can find a more natural approach to flipping the cellular switch so to speak and help those suffering with obesity—at least until more is understood about its complexities.

In addition to showing how fasting and intermittent fasting may help in weight management, the research has also confirmed the long-known benefits of being cognizant of when you eat. Researchers found that placing time restrictions on when people ate also resulted in broad systemic effects and triggered the same biological pathways as long-term fasting. It also improved cardiometabolic risk factors such as insulin resistance, high cholesterol and inflammation, decreased fat and comparable weight loss similar to long-term calorie restricted regimens.

Long-term, calorie-restricted diets just don’t work. Finding a way to activate the metabolic “switch” in obese people may be the start of some very important metabolic disease research.

One key mechanism responsible for many of the beneficial effects of fasting is that it appears to be “flipping” the metabolic switch of energy consumption. But what is this metabolic switch and how is it flipped? Simply put, it’s when the body stops using sugar for energy and begins to use fatty acids and fatty acid‐derived ketones. Hence, the focus on ketogenic diets today. A growing body of research indicates that ketones are the preferred fuel for both the brain and body during periods of fasting and extended exercise.

Also of note is that this “switch” represents a shift from lipid synthesis and fat storage to the mobilization of fat in the form of free fatty acids (FFAs) and fatty acid‐derived ketones, all which is a boon to weight management. For this reason, many experts have suggested that intermittent fasting regimens may have potential in the treatment of obesity and related metabolic conditions, including metabolic syndrome and type 2 diabetes.

The metabolic switch typically occurs in the third phase of fasting when glycogen stores in hepatocytes are depleted and accelerated adipose tissue lipolysis produces increased fatty acids and glycerol. The metabolic switch usually occurs between 12 and 36 hours after food is consumed depending on the liver glycogen content at the beginning of the fast and on the amount of the individual’s energy expenditure/exercise during the fast.

During the switch, the lipids glycerol and diacylglycerol are metabolized to FFAs, which are released into the blood. At the same time, other cells may also begin generating ketones. FFAs are transported into hepatocytes, where they are metabolized to produce ketones and acetoacetate, which is formed in the liver during fasting periods and may induce mitochondrial biogenesis, or in normal people-speak, cause cells to increase their individual mitochondrial mass in response to greater energy expenditure. In other words, the brain and body are functioning at a high capacity running off the energy produced by ketones, not sugar.

Fasting has been used as both a religious and a medical practice for thousands of years. Fasting for medical purposes has been suggested since the time of ancient Chinese, Greek and Roman physicians. Benjamin Franklin recommended fasting and has been quoted as saying, “The best of all medicines is resting and fasting.” Similarly, Mark Twain wrote, “A little starvation can really do more for the average sick man than can the best medicines and the best doctors. I do not mean a restricted diet; I mean total abstention from food for one or two days.”

But before you decide on doing an uncontrolled fast, be aware that there are health risks and check with your physician on whether or not intermittent fasting may help you gain control of any metabolic issues you may be experiencing. Although the science has been promising in showing how fasting may pay a key component in flipping the metabolic switch, it is hardly set science and further research on how ketones switch the energy burning mechanisms of the body is still needed.

I am hopeful that obesity research that focuses on obesity as a disease and not a moral failing will continue to shed light on the causes and treatments for obesity. For far too long, the medical community has publicly beat up on the obese by castrating them as being lazy, indulgent, and out of control. And indeed, there is a component to having self-control in weight management and in being mindful of what you eat, the amount you eat and sustaining from processed foods that are loaded with sugar. However, labeling 35 percent or more of the U.S. population as being somehow morally deficient is perhaps one of the cruelest medical misdiagnoses in modern history. Reign well.