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Why This RD Is a Fan of Intermittent Fasting


Photo: Xphi Dech Pha Ti / EyeEm / Getty Images

As a registered dietitian, I customize food plans and advise clients all over the world from our Foodtrainers offices. Every day, several of these clients come in asking about different fad diets and food trends. Some are silly and easily dismissible (looking at you, juice cleanses). Others are "new" (but often very old) and potentially useful. Intermittent fasting falls into that category.

Between our office and Instagram, I now hear questions on a daily basis about intermittent fasting (IF). Many fans of IF say that it can make you leaner, stronger, and faster, while boosting your energy and helping you sleep better. Okay, with benefits like these, should we all be fasting?

When you hear the word fasting, you may think religious fasting or hunger strikes, like the kind that Gandhi did. But fasting has been used as a mechanism for healing for centuries too. 

That's because digestion takes up a lot of physical energy. The idea is that by taking a break from eating, your body can focus on other processes, like regulating hormones, decreasing stress, and reducing inflammation. Even though fasting is becoming more popular (it's commonly recommended as part of a keto diet), it's actually an old-school concept, tracing back Ayurvedic medicine, which says to avoid snacks for this reason. (More: Everything You Need to Know About Intermittent Fasting)

Research on the benefits is still very new, but the anecdotal evidence looks fairly strong. We even use IF in our office as part of a weeklong "Foodtrainers Squeeze" reset program, and hundreds of participants report fantastic improvements in their energy, weight, and sleep. There are several types of intermittent fasting, from intro level to full-blown water fasts (which I do not recommend unless supervised by a doctor). I also do not recommend IF during pregnancy or for those with a history of disordered eating/restriction.

The intro/medium level of IF is what I use most often with clients, called 16:8. This means having a 16-hour food-free window, then an eight-hour window of regular meals. So if breakfast is at 10 a.m., you need to eat dinner by 6 p.m. At Foodtrainers, we have run hundreds of clients through this, and we find the optimal timing of meals is 10 a.m. breakfast (do not skip breakfast!!! This is not about skipping meals), 2 p.m. lunch, 6 p.m. dinner. Then, as we say at Foodtrainers, the kitchen is closed! (If you're hungry in the morning, try these easy breakfasts you can make in 5 minutes.)

Of course, this is not always possible if you have a real life and like to socialize and don't bring your dinner to work. So I'd suggest trying this two to three days a week to start, on days when you have total control of your meals, and see how you feel. It's not something to be employed 24/7/365.

As always, the quality of your diet is still key: Tons of veggies, lean proteins like wild fish, organic chicken, pasture-raised eggs, and good fats like olive oil, coconut oil, nuts, seeds, and avocado are ideal. The goal is to have nourishing, solid meals, not to starve yourself.

As for liquids, if it's outside of your eight-hour eating window, you want to keep it to mostly calorie-free beverages. Here's the deal on what you can drink during intermittent fasting:

  • Water is important and a freebie. Drink as much as you can (~80 to 90 ounces for most people).
  • Tea is your friend. I love loose-leaf teas.
  • No sodas (even diet) or fruit juices.
  • Your morning coffee is fine. There is a rule among the bulletproof/paleo/keto communities that your body remains in a fasting state as long as you consume under 50 calories of fat (think coconut oil in your coffee, a splash of whole coconut milk, unsweetened/homemade almond milk, or even a splash of heavy cream). Hallelujah coffee gods!
  • Alcohol is a no. Not only is alcohol caloric, and most likely taking place outside of your eight-hour eating window, it is still a toxic compound and puts your body through stress to metabolize and get rid of. So skip alcohol, and stick to water, tea and sparkling water on IF days.


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