Clock on white plate with fork and knife, intermittent fasting, meal plan, weight loss concept on … [+] With the holidays upon us and everyone focused on watching their waistline, it’s a natural to think about the ideal diet to prevent weight gain and maybe even promote weight a little loss.
Let’s face it, it’s really difficult to go on a “diet”. Diets are faced with a high risk of failure with the bulk of them failing, ending with eventual weight gain above and beyond where you started.
The concept of caloric restriction which has been explored as a way to improve longevity has been shown to be successful in animal models (mice), offering an enticing possibility to humans. But implementing this into your daily lifestyle may be problematic and may not be realistic in the long run.
Another more intriguing approach that has been gaining popularity in the past decade is intermittent fasting (IF), a form of time-restricted eating.
In a nutshell, it’s a way to extend the window of time during the day in which you don’t eat. Instead of eating from the time you awaken, the goal is to delay the onset of eating, thereby extending your fasting period that naturally occurs when you sleep.
IF involves only eating for a defined period of time in a 24-hour period. For example, it may involve eating for an 8-hour period during the day—as opposed to grazing on food all day long—and fasting for the remaining 16 hours. (During the fast, you are permitted to drink water, have black coffee, or tea.)
For example, instead of eating from 7 am when you awaken, you would begin eating at 11 am or noon until 7 or 8 pm. When you do eat, the goal is to eat moderately, although you are permitted to eat the foods that you would normally eat.
Variations on this theme include the 5:2 approach (eating normally 5 days a week and approximately 500-600 calories 2 days week), or alternate day fasting (ADF).
With IF becoming more popular, it’s important that physicians and other healthcare professionals be aware of the principles and science behind the diet in order to have a rational discussion with their patients.
In an article published today in the New England Journal of Medicine , Mark Mattson, PhD , a neuroscientist at Johns Hopkins School of Medicine, explains the nuances behind the approach to IF, along with why he adopted this approach to eating more than 20 years ago.
Mattson’s personal reasons for adopting intermittent fasting began well before he embarked research into the topic itself. It actually began about 35-40 years ago as a method he could use to reduce symptoms related to acid reflux which he found were worse if he ate breakfast and then rode his bike to work in the research lab.
“I started doing it way back in graduate school at the University of Iowa in the early 80s,” he explained. “So I quit eating breakfast and found that I didn’t get the reflux—and I haven’t eaten breakfast since then!”
Little did he realize that this was at the beginning of a pursuit of a concept that would shape his research, and have broad implications for disease management, metabolism as well as weight loss.
Health Benefits of Intermittent Fasting
While certain subgroups of patients, including those with diabetes and pre-diabetes may benefit from adopting this approach to eating (by lowering HB A1C levels), its value and principles certainly extends to other subgroups including those with cardiovascular disease, neurologic ailments (multiple sclerosis, Alzheimer’s and Parkinson’s disease) and patients with cancer.
While IF may facilitate weight loss by reduced caloric intake, its more important benefits include improved glucose regulation via lower insulin levels, reduced blood pressure and lower resting heart rate, all indicators of improved health.
There may also be a reduction in weight-related medical conditions such as elevated cholesterol, and non-alcoholic fatty liver disease (NAFLD), offered Dr. Minisha Sood, an endocrinologist at Lenox Hill Hospital, in New York City.
“Importantly, intermittent fasting or alignment of eating with our natural circadian rhythms may positively impact the gut microbiome which could improve overall metabolism and health,” she explained.
The concept by which this is facilitated is known as “metabolic switching”, which according to Mattson, is a healthy homeostatic mechanism that evolved in Homo Sapiens over thousands of years during periods when food was scarce. This involves switching by our body’s cells from using glucose during the fed state to free fatty acids (FFA) and ketone bodies during periods of starvation. This switch, which is metabolically advantageous, actually serves to reduce inflammation by utilizing adaptive pathways in our cellular machinery.
As Mattson explains, glucose is the normal fuel our bodies rely on during the “fed” state. When we eat, excess glucose beyond immediate caloric expenditures is stored as a compound known as glycogen in the liver for quick burst of energy, but excess as fats (triglycerides). Triglycerides or fat is broken down to compounds known as “free fatty acids” (FFA) along with glycerol. Further metabolism of FFA by the body produces compounds known as “ketone bodies” which are used by the brain, heart and other organs during periods when glucose is not immediately available.
Clearly IF is not for everyone, with lifestyle, age, medical history, work hours (shifts) and personal preference being key factors that may influence the ability to adhere to this lifestyle and approach to eating, as Mattson explains. There may also be sex differences and genetics that ultimately influence individual success with IF.
“Time restricted eating or intermittent fasting may be actually easier to stick with than daily calorie restriction or daily calorie control,” explained Sood. When studied head-to-head, intermittent fasting and daily calorie restriction are both equally effective for weight loss so it’s really a matter of finding an approach which works with one’s lifestyle and which can be followed consistently.”
In regard to potential downsides of IF, Sood explained that “some people may experience increased hunger toward the end of the fasting period each day—the hunger response may wane over time and […]