October 5, 2015

Dear Melissa, Can I Intermittent Fast During my Whole30?


Welcome to Dear Melissa, where I answer your questions about transitioning into or completing a Whole30, successfully sticking to your new healthy habits, and figuring out how to make this lifestyle work in the real world. Today, I’m helping you decide whether Intermittent Fasting (IF) is a good protocol to add on top of your Whole30. (Spoiler: no.)

Dear Melissa,

I am on day 30 of my second round of the program and have been reading a lot about intermittent fasting. I am going to continue this Whole30 into a Whole60 (feeling too great to stop now!) and wanted to know your opinion on incorporating intermittent fasting into my day. I know that there is a huge emphasis on Meal 1 during the Whole30, so should I wait until after my Whole60 is over, or would starting an 8-hour feeding window (11am-7pm) then fasting overnight hurt my progress? –Robin

Dear Robin,

I’ve been meaning to address this topic for years, so I’m glad you asked. First, let’s give some background on Intermittent Fasting (IF).

IF is essentially not eating for a set period of time (16 hours is a popular time frame, but fasts can extend as long as a full 24 or even 36 hours), and consolidating your “feeding window” into a shorter period of time. As an example, you’d occasionally fast from 8 PM until noon the following day (eating nothing, but drinking calorie-free beverages like water, black coffee, or tea), then eat your breakfast, lunch, and dinner all within an 8-hour window between noon and 8 PM. You’d repeat this pattern intermittently, inserting this “fast” here and there throughout your week.

IF is convenient, allowing you to simply not worry about food for a good part of a busy day, or skip the challenge of finding healthy food on a day when you’re traveling. It also gives your body a break from digestion, and by restricting energy, forces it to use the fuel it’s already got (ideally, body fat) to power you through your day. And the scientific literature is pretty solid; benefits can include everything from improving insulin sensitivity to reducing oxidative (inflammatory) stress on the body to, yes… weight loss. Because let’s be honest, this is why most people come to IF.

So you’d think that combining the Whole30 (which addresses what you eat) with IF (which addresses when you eat) would be a magic bullet to better health and faster weight loss. Not so fast.

Here’s why I don’t want you to IF during your Whole30 (or Whole60).

Don’t Complicate the Process

First, the purpose of the Whole30 is very specific; we’re out to change your health, your habits, and  your relationship with food. The program eliminates, then reintroduces, foods that are very commonly problematic across four areas; your cravings and emotional relationship with food, your metabolism, your digestion, and your immune system. The Whole30 is very carefully designed to help you identify the foods that make you less healthy, and teach you how to create the perfect diet for you.

My point? There’s already a lot going on here, so please don’t throw an IF monkey wrench into the works.

If you change too many things at once, you’ll never know what’s responsible for the positive or negative effects of your new dietary protocol. And the most important thing you could do for your health is finish the Whole30 exactly as written, including reintroduction. Figure out how changing your food choices affects your cravings, your energy, your sleep, and your body composition, without complicating the process by adding periods of  fasting (which can influence cravings, energy, sleep, and body composition). Approach it like a scientific experiment, where everything but your food choices stay basically the same, so you can evaluate the impact.

This is especially true if you’re one of the people for whom IF isn’t a great idea in general (read on, because that’s most of you). If this is you, you’ll combine the two, and come to the conclusion that the Whole30 just didn’t work for you… when in fact, it’s far more likely that the regular fasting was to blame for your lack of results.

You’re Doing it Wrong

In addition, most people don’t practice IF the way they’re supposed to. You do it every day, which isn’t very “intermittent.” And you don’t eat anywhere near a day’s worth of calories in your feeding window, because it’s hard to consume that much food in such a short period of time. (This is especially true if you’re also on a Whole30, where everything you’re eating is real food, and therefore incredibly satiating.)

In addition, most people new to Paleo or the Whole30 gravitate to IF because they’re already hormonally “off,” and they wake up just not feeling hungry. For these folks, it’s not a stretch to push Meal 1 out until 10 or 11 AM anyway, but now they’re able to put a name to it. “Oh, I’m not metabolically messed up, I’m intermittent fasting.” They eat Meal 1, and likely Meal 2 (dinner), but that entire Meal 3 is just plain missing, unless you count foraging through the pantry with uncontrollable cravings at 8 PM a meal.

I’ll put it another way: most of you aren’t actually intermittent fasting. Your hormones are off, and you’re just not eating.

Yes, of course, you’ll lose weight… because you’re essentially on a crash diet. You’re starving yourself multiple days a week (or every day) under the guise of IF, but what’s really happening is that you’re just not eating enough, and actually making your metabolic situation worse, not better. And we all know how that goes, in the long term.

Enter stress.

Too Much Stress

The most important reason for avoiding IF during your Whole30 has to do with your context; how much stress can you really handle right now?

IF is inherently stressful on the body. (Remember, you’re purposefully depriving it of any form of energy for 16-24 hours.) Even if you’re doing it right, eating enough calories to sustain your activity levels and health during your short feeding window, it’s still stressful to go without food for that long. And you’re doing that several times a week.

This is especially true if you’re new to the Whole30, and have not yet allowed enough time to become “fat adapted.” (See page 164-165 in It Starts With Food). Until you teach your body to stop relying on sugar for energy and start using your body’s own fat stores (a process that starts in a few days, but can take many weeks to fully manifest), IF will only serve to make you feel awful. Imagine the Day 3 “Hangover” plus the Day 5 “Kill all the Things” plus the Day 10 “Hardest Day” (and a ton of cravings to boot) and you’ll get the idea. Plus, in your context, depriving your body of energy before it knows what to do with your body fat stores is even more stressful.

How many of you can afford to add more stress to your life?

Adding IF to an already stressed system can backfire, leaving you less metabolically healthy (and less lean) than when you started. Functional Medicine provider Chris Kresser has noticed this in his patients, and some research suggests that IF has an even more profound consequences for women.

Who Should IF?

In summary, if you are:

  • Done with a full, by-the-books Whole30 plus reintroduction, and are successfully riding your own bike, still eating mostly Whole30-ish foods
  • Have no medical condition that would preclude playing around with food timing and restriction (like a history of eating disorders)
  • Successfully managing the stress in your life; sleeping 8-9 hours a night, eating enough nutrient-dense food, training smart, recovering effectively, working reasonable hours (not night shift!), and not under any significant psychological stress
  • Already fat-adapted; don’t need snacks between meals, and able to miss a meal due to a busy day and not get cranky, lethargic, or foggy
  • Willing to do the work entailed in getting a healthy amount of calories in during your feeding window
  • Sticking to an “intermittent” schedule, not making it a daily habit

Then you can try intermittent fasting. But only if all of these conditions apply, and even then, only if this feels relatively easy for you.

If you get into it and find yourself counting down the minutes until you can eat every time you try; if you’re cranky, craving, or mental performance declines when you fast; or if you notice signs of stress creeping into your life (not sleeping as well, gaining weight, especially in the midsection, not performing as well in the gym or recovering as effectively, energy dips and slumps), these are all signals that IF is not working well for you, in your context.

A smarter move might be to play around with this (still given the above conditions) only when it’s really convenient. For example, some travel days, I’ll choose to IF, because not eating is easier than packing a healthy breakfast and lunch for a six hour flight. If you play around with it here and there like that, you may get the best of both worlds; reaping the benefits of IF without the stress overwhelming your system.

Best in health,