Have you heard people talking about intermittent fasting? Fasting involves organizing your eating into a schedule of extended periods without food consumption punctuated by smaller windows where you’re allowed to eat, and proponents claim it can help you lose weight, prevent illness, and even add years to your life. But what is the intermittent fasting diet, and should you try it? Here are some facts to consider.
What is intermittent fasting?
As the name implies, intermittent fasting means cycling between eating and fasting. Unlike most diets, which tell you what you should and shouldn’t eat, intermittent fasting is all about when you eat. Although this type of diet may seem like a new phenomenon, Healthline reports that humans have actually been fasting for thousands of years, whether because they simply didn’t have much food, for religious reasons, or during periods of illness. As modern science has explored the potential health benefits of intermittent fasting, this way of eating has become increasingly popular. As explained by Men’s Journal, there are a few different ways to fast intermittently.
Alternate Day Fasting
This method involves consuming nothing but water plus 500 calories (200 of which should be protein) for 24 hours, then eating the way you want for 24 hours. The 500 calories can come from one meal or spread out through the day. This cycle is repeated every two days, so you get to eat what you want every other day.
To follow this diet, you pick two non-consecutive days every week to consume no more than 500 calories, including 200 calories from protein (all at once or spread throughout the day). Then you eat whatever you want the other five days of the week. People like this diet because they find only two days of fasting to be manageable, especially when they know they can eat anything on non-fasting days.
You already fast at night while sleeping, and this diet extends that fast. Also known as time-restricted feeding, the 16:8 diet involves fasting each day for 16 hours out of 24, then eating whatever you want during an eight-hour window. Many followers of this diet don’t eat anything before noon and stop eating at 8 pm. If you’re not much of a breakfast eater anyway, this diet may be relatively easy for you to implement.
Fasting Mimicking Diet
Valter Longo, PhD from USC has developed a very strict diet meant to be followed for 5 days at a time (done every 3 months or so, depending on your own medical issues) which he espouses is the best way to gain the longevity benefits from fasting. He writes about the science behind his approach in his book, The Longevity Diet. I’m planning to give his diet a try – so I’ll keep you posted how that goes.
What are the benefits?
Intermittent fasting has the potential to improve health in a number of ways, including:
- Weight Loss: Fasting lowers insulin levels, allowing your body to burn fat stores for energy. A huge analysis conducted in 2017 by the International Society of Sports Nutrition found that intermittent fasting works as well, if not better, than conventional calorie restriction for improving body composition. And it seems to be particularly good for people who are looking to burn fat without losing muscle. As Krista Varady, Ph.D., an associate professor of kinesiology and nutrition at the University of Illinois at Chicago, told Men’s Journal, “When people lose weight, typically 75% is fat loss and 25% is muscle mass. But with fasting, the ratio actually changes so that 90% of weight loss is fat and 10% is muscle.” Varady also said that the stabilizing effect of intermittent fasting on insulin levels could make it a good diet for people with type 2 diabetes.
- Heart Health: Intermittent fasting may reduce your risk of heart disease, according to the Mayo Clinic. Not only does fasting help you maintain your weight and blood sugar levels, both of which are important for heart health, it can also lower your LDL (“bad”) cholesterol levels. See my posts here and here for more information on how diet can affect heart health.
- Brain Protection: Mark Mattson, chief of the Laboratory of Neurosciences at the National Institute of Aging in Baltimore, told The Guardian that fasting could help neurons by providing them with a fuel alternative to glucose. He added that these types of diets may also protect aging brains from diseases like Alzheimer’s and Parkinson’s.
Wondering what others areas of your health could use your attention? Consider taking my Optimal Men’s Health quiz. It’s designed to help you determine your next best step to getting healthier and closer to winning.
Myles Spar, MD, MPH is board-certified in Internal Medicine and in Integrative Medicine. As a clinician, teacher and researcher on faculty of two major medical centers, he has led the charge for a more proactive, holistic and personalized approach to care that focuses on cutting edge technology and preventative care. Dr. Spar has traveled with the NBA, presented a TEDx Talk, appeared on Dr. Oz, and been featured in publications such as the Men’s Journal and the Los Angeles Times.
On your 16.8 intermittent diet can you have coffee before the 16 hours are up. That would be all I need after I wake in the morning.
Can you have coffee during the hours of fast on 16:8.
How many calories should I consume 5 days week? when fasting.
It depends on your size and energy level, but generally 20% less than what you’d eat if you weren’t fasting
Can you drink water during the 16 hours of fasting?
I read that you can have coffee before the end of the 16 hr fast, but can you have coffee with flavored creamer?