The Simple Rules of Intermittent Fasting (0:40)
Why is everyone talking about intermittent fasting? Because it’s easy. It’s also a key part of Dr. Oz’s new System 20 lifestyle plan, which aims to help you lose 20 pounds and lower your risk of heart disease, diabetes, and stroke by 20%. But why is intermittent fasting good for you? Beyond just helping your body burn fat faster, a new study shows potentially huge health gains that go beyond the scale.
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For the purposes of this latest review, published in The New England Journal of Medicine in Dec. 2019, authors Mark Mattson and Rafael de Cabo focused on time restricted eating (consuming all your calories within 6-8 hours and fasting for 14-16 hours per day, which is what’s recommended on System 20), as well as what’s referred to as 5:2 fasting (fasting two days per week, capping the amount of calories consumed on a fasting day at about 500). Both approaches seem to have similar benefits. But a new review of studies published in The New England Journal of Medicine appears to support the hypothesis that intermittent fasting can help lower blood pressure and aid in weight loss. Additionally, intermittent fasting is typically practiced by a culture known for their longevity and, in animal studies, intermittent fasting has shown efficacy reducing degenerative brain diseases.
Mattson suggests that intermittent fasting can improve overall cellular health, possibly by sparking something called “metabolic switching.” Metabolic switching means that cells make the jump from using sugar for energy (which comes from the liver) to using ketones for energy (which come from fat cells). But the most intriguing part of this study is Mattson and de Cabo’s suggestion that intermittent fasting may improve insulin resistance and help adherents maintain a more balanced blood sugar throughout the day, which could be hugely beneficial to individuals with certain metabolic issues and Type 2 diabetes (formerly known as adult-onset diabetes).
An encouraging 2018 case report out of Toronto, Canada showed that men with Type 2 diabetes were able to reduce their reliance on insulin after fasting for several days each week. However, it’s crucial to note that the case report included only three men — an extremely small sample size.
If you don’t suffer from diabetes or certain other metabolic conditions, that doesn’t mean intermittent fasting can’t improve your health as well. Several markers of cardiovascular health — like blood pressure and resting heart rate — got better when individuals practiced this technique.
There may be mental health benefits, too. Researchers saw improvements in cognitive performance in animals that participated in various studies, like positive changes in spatial and working memory. Additionally, one study in elderly humans saw improvements in verbal memory. In the study, 29 women with a median age of around 60 increased their verbal memory scores by an average of 20% after following a calorie restricted diet for three months. All of this taken together means that it’s possible that intermittent fasting may improve your health now, and lengthen your life overall — and that it could improve the quality of that longer life, too.
A note of caution: While there are some promising results, it’s also undeniable that researchers still aren’t 100% clear on whether the practice of fasting — or the weight loss people tend to experience after following this eating schedule — are the cause of these benefits. There also hasn’t been enough research comparing the differences between the two main types of fasting schedules (time restricted eating and 5:2 fasting), so there’s no way of knowing right now if one type better promotes certain outcomes than the other.
The majority of the research we have access to today has been done on animals and rodents, so more studies still need to be conducted on humans to get a better understanding of how intermittent fasting affects all aspects of human health, especially in the long-term. However, this most recent review is still promising, and supports healthy lifestyle plans like System 20, which incorporate intermittent fasting as a regular, (almost) daily practice.