When (Not) to Eat Part 2: Intermittent Fasting 0
Posted on 22, January 2018
in Category Tips
Two weeks ago we addressed how overnight fasting, or time-restricted feeding, can lead to weight loss, improved insulin sensitivity and reduction in certain disease risk factors. Missed it? Here’s the link. This week we are addressing a more rigorous type of dietary fasting approach, which is Intermittent Fasting.
Intermittent Fasting is the hot new dietary approach, but it is grounded in research that has been around for years. It has been well established that a calorie restricted diet, one that reduces calories by 15-40%, can increase lifespan and decrease risk factors for chronic diseases and slow the aging process. This has been seen in animal and human studies, but there is only one problem with long term calorie restriction, it’s difficult. People don’t want to restrict calories for the remainder of their years. Food and drinks are meant to be enjoyed, after all. Researchers explored the concept of whether there is a way to get the benefits of a calorie-restricted diet without restricting calories by restricting when people eat. And thus, the concept of intermittent fasting is born.
What is Intermitting Fasting?
Generally speaking, it is a type of eating that cycles periods of eating and fasting. Intermittent fasting plans very in length and frequency, there isn’t one standard definition. Three examples of popular Intermittent Fasting plans include:
16:8. This type of daily intermittent fasting is 16 hours of an overnight fast followed by an 8-hour eating window. This could be accomplished by eating meals between 10am and 6pm. There is not a calorie restriction in this approach.
Eat-Stop-Eat. This diet recommends that people do a 24-hour fast on one or two non-consecutive days per week, but does not restrict calories on subsequent days.
5:2. This diet recommends fasting on two non-consecutive days, where calories are restricted to 500-600 on fasting days.
There is no medical consensus on the “best” method of intermittent fasting.
Health benefits of Intermittent Fasting
Weight Loss. By compressing the eating window, or completely restricting calories this will create a caloric deficit for most people, which results in weight loss. Fasting also helps to regulate the hormones associated with hunger, such as ghrelin and thus some people report that they “feel” less hungry between meals and while fasting.
Fat loss. In an absence of calories, particularly carbohydrates, the body will turn to fat stores as a source of energy. There is a potential for the body to utilize muscle as energy, but this is more likely the case during an extended water-only fast. There is more research needed to determine the extent to which muscle loss occurs during fasting.
Metabolic Health. Both rodent and human studies have shown that periodic bouts of fasting improve blood glucose levels and circulating insulin levels. Intermittent fasting also decreases markers for inflammation in the body associated with stress and chronic disease.
Increased Longevity. Recent studies have found that intermittent fasting changes the way that our mitochondria network with each other and how they age. Mitochondria regulate the pathways that control aging. Intermittent fasting helps keep the mitochondria in a more “youthful” state. Fasting also promotes cellular autophagy, which is essentially your body’s cleaning system. Autophagy is a process in which the body seeks out, breaks down and consumes damaged DNA and damaged cells caused by aging, disease or stress.
Human Growth Hormone (HGH) is produced by the pituitary gland and released to the liver where it is used for muscle growth and development. In adults, HGH typically decreases over time, resulting in decreased muscle mass, increased body fat and decreased bone density. Fasting stimulates the release of HGH. A study on adult men showed a 5-fold increase in HGH after a 2-day fast. The implication here is that the body has protective mechanisms in place to preserve (and even grow) lean body mass during short periods without food. For athletes, intermittent fasting may be a natural way to boost HGH levels.
Insulin Growth Factor-1 (IGF-1). IGF-1 is linked with cancer tumor growth, and diseases such as diabetes. Fasting decreases IGF-1 levels, which could help slow the progression of some tumors.
Is Intermittent Fasting Right for Me?
This dietary approach is not for everyone. Intermittent Fasting is still a relatively “new” dietary approach and there are very promising animal studies which suggest that it could be a highly beneficial lifestyle intervention to improve health and increase longevity. More human studies are beginning to emerge, but there is still a lot to learn. Speak with your physician, Registered Dietitian or qualified medical professional before beginning an Intermittent Fasting routine. There are many conditions for which this type of fasting would not be appropriate. The intent of the article is meant to convey the research surrounding Intermittent Fasting.