Paleo Intermittent Fasting: How to Get the Benefits of Both Diets | Chris Kresser

Paleo Intermittent Fasting: How to Get the Benefits of Both Diets

by Katie Melville, Ph.D.

Published on

paleo intermittent fasting
Should you combine Paleo and intermittent fasting? iStock/yacobchuk

Can you practice intermittent fasting (IF) while also eating Paleo? Absolutely! Read on to learn how IF is in tune with ancestral health, how to implement IF while Paleo, and troubleshooting tips.

Paleo goes together naturally with intermittent fasting. Check out this article from Katie Melville for tips on implementing intermittent fasting while Paleo and a troubleshooting guide to help you make the most of your ancestral diet. #paleo #nutrition #wellness

Paleo and Intermittent Fasting: Defining Our Terms

Paleo

Although “Paleo” can mean different things to different people, in general, the Paleo diet, also called an ancestral diet, focuses on a variety of nutrient-dense foods:

  • Animal products like meats, organ meats, seafood, shellfish, and eggs
  • Starchy and non-starchy veggies
  • Fruits, nuts, and seeds

In some cases, when well-tolerated, an ancestral/Paleo diet can even contain dairy, properly prepared legumes, and grains.

Chris has written extensively on the health benefits of an ancestral diet, which include: (1, 2, 3, 4, 5, 6, 7)

  • Weight loss
  • Improved metabolic health
  • Better cognition and mental health
  • A lower risk of developing chronic diseases like diabetes, obesity, and cardiovascular disease

Intermittent Fasting

IF is an umbrella term that includes any diet with time-restricted eating windows. The variations depend on personal goals, health status, and lifestyle. IF can be as casual as skipping a meal occasionally while traveling and no good food options are available. Or IF can be a daily practice, where you eat only during a six- or eight-hour window of the day and fast the remaining part of the day, called 18:6 or 16:8. You can also practice IF by fasting for a full 24 hours every other day, or once or twice per week.

IF doesn’t necessarily mean running on a calorie deficit. In fact, you could lose weight even if you aren’t intentionally trying to eat less. In a rodent study, mice who had free access to food only eight hours of the day lost weight after 100 days compared to mice who had free access to food 24 hours per day, despite eating the same amount of calories from the same kinds of foods. (8)

In addition to weight loss, IF boasts many other benefits:

  • Lower blood pressure (9)
  • Gut health improvement (10)
  • Increased insulin sensitivity (11)
  • Reduction in cardiovascular disease risk (12)
  • Protection against memory loss and neurological disorders (13)
  • Decreased inflammation and oxidative stress, which underlie most chronic diseases (14, 15)
Adopting a nutrient-dense, anti-inflammatory, real-food diet like Paleo is often the quickest way to hit your body’s reset button so you can lose weight, improve sleep, boost energy, and reduce inflammation. For many people, practicing IF is a great way to complement those Paleo health benefits. But changing up your diet and eating habits isn’t always an easy process. It takes support and accountability—which health coaches can offer.

Health coaches are behavior change experts who understand how motivation really works. They support clients who are trying to change by helping them learn how to tap into their own motivation and inner strength to achieve their goals. If you’re encountering obstacles in your path toward health, working with a coach might be the way forward. And if you’re passionate about health and helping others achieve their vision of well-being, working as a health coach could be the right path for you. 

Find out what health coaches do and how they make a living with the ADAPT Health Coach Training Program.

How Paleo and IF Work Together

IF has an inherent Paleo/ancestral quality. Our ancestors didn’t have continuous access to food like we do today, with drive-throughs, grocery stores, and refrigeration. IF was part of life, when hunting or foraging didn’t go well.

During a fast, your cells switch from using glucose as the primary energy source to using fat. (16, 17) The time it takes for this switch to happen may be as early as 10 hours after food consumption has stopped, but some evidence indicates that 18 hours is needed for the full effect. (18) Our bodies have evolved to function efficiently by switching between using fat or glucose as the primary fuel source.

Before even attempting IF, your diet should already look Paleo-ish, or at least it shouldn’t resemble the standard American diet. If your body is used to running on processed carbs and sugar all day long, and you’re eating late into the night, never allowing your body to practice using fat as the primary fuel source, then you’ll crash trying to do IF.

Other aspects of a Paleo lifestyle are cornerstones of IF. You also should be getting good sleep, managing your stress, and exercising regularly before implementing IF. IF stresses the body, so you need to make sure your body isn’t already stressed out from lack of sleep or a huge life stressor. You want IF to be a hormetic stress—a slight or moderate stress that makes the body stronger—instead of a stress that wreaks havoc on your system.

How to Implement Both Paleo and IF Together

Let’s say you’re ready to try the 16:8 IF. As stated above, you’re already eating mostly Paleo, you’re sleeping well, and you’re not currently in a high-stress situation. Here’s what that process might look like.

Ease into It

Instead of going from zero to 60 in one day, gradually ease into IF for a week or two:

  • First, lower your carb intake so that your body stops having hunger-causing insulin spikes and dips.
  • Next, stop snacking in between meals and especially after dinner.
  • Then, move dinner a bit earlier and/or move breakfast a bit later. Stretch the time in 30-minute intervals until you’re fasting for a full 16 hours between dinner and breakfast.

Expect some hunger during the transition. Your body gets used to eating when you usually feed it, and it takes time to adjust to a new eating pattern. Feel free to drink non-caloric beverages like tea and water in between meals. If you’re struggling a bit more, you can even try a little bit of bone broth for a few days to help tide you over during a fast. Be careful with black coffee. Although considered calorie-free, it can spike cortisol levels and ultimately cause more hunger. (19)

Once your feeding window fits within eight hours, you might find that two larger meals work better than three regular-sized meals. It’s not a one-size-fits-all approach; you’ll have to tweak your meals to see what works best for you personally.

Consider the Whole30 Meal Template

Co-founded by Melissa Hartwig Urban, the Whole30 Program is similar to Chris’s Paleo Reset plan from The Paleo Cure. For 30 days, you avoid dairy, legumes, beans, grains, all desserts (including “Paleo desserts”), and a long list of food additives and preservatives. Whole30 can be a great way to prepare for Paleo IF, especially if you’re not quite eating Paleo yet.

With specific meal templates, Whole30 focuses less on what you can’t eat and more on what you should be eating. The Whole30 program requires three full meals per day, and each meal must contain:

  • Two to three cups or more of vegetables
  • A portion of protein that reflects your needs and activity level
  • Occasionally a piece of fruit
  • A “plated fat” portion that reflects your energy needs

This “plated fat” helps keep you full between meals, which is why Whole30 can work well when beginning IF. A plated fat isn’t just the fat you cook your meat with, but an additional, intentionally added fat, such as:

  • One-half of an avocado
  • Nut butter
  • Nuts
  • Coconut milk
  • Paleo mayonnaise
  • Olives

If you follow the Whole30, three-meals-a-day template, your body will be more prepared to tackle IF. In fact, if you’re eating breakfast at 7 a.m. and dinner at 5 p.m., you’re already most of the way toward a 16:8 eating pattern.

Six Tips to Help You Get Started and Troubleshoot through Problems

If you’re considering Paleo IF, check out these six tips to help you get started and to keep you going.

1. Make Sure You’re Eating Enough

Despite access to food 24/7, nearly one-third of Americans are at risk of being deficient in one or more nutrients. (20) Even Paleo dieters can be susceptible to nutrient deficiencies, like calcium and iodine. (21) With a shortened eating window, you may struggle with getting enough calories or enough of the right nutrients. Be sure to focus on eating a variety of nutrient-dense foods.

2. Cook in Bulk and/or Meal Prep

If you’re cooking three meals per day from scratch using complex recipes, you might not have enough time to chop, prepare, cook, and eat everything in an eight-hour window. Embrace leftovers, and do a little planning:

  • Double or triple a dinner recipe, and save the leftovers for lunches over the next few days.
  • Plan your meals to repurpose proteins or other meal components. For example, use leftover grilled chicken from dinner on a salad the next day.
  • Spend an evening after your feeding window chopping all the vegetables you’ll need for the next few days’ meals, and store them in the refrigerator until needed.

3. Choose Your Eating Window

On the 16:8 IF plan, should you eat between 8 a.m. and 4 p.m. or between noon and 8 p.m.? The jury’s still out, but it seems that “skipping dinner” may be superior to “skipping breakfast.” In one study that closely examined these two eating patterns, fasting until noon decreased insulin sensitivity, the exact opposite desired outcome of IF. (22)

Again, you’ll have to experiment. Maybe eating between noon and 8 p.m. really, really works for you. Ideally, your last meal should be at least three hours before you go to sleep, so unless you’re going to bed at 11 p.m., a window of 11 to 7 or 10 to 6 might work better. Eating late at night is linked to trouble sleeping and weight gain, and can mess with your circadian rhythm. (23)

4. Keep Your Exercise Goals in Mind

Depending on the strictness of IF, gaining muscle during this eating approach may be difficult. If you’re able to eat a calorie excess using the 16:8 approach, bulking while doing IF is possible, but less likely if you’re fasting 24 hours a couple times per week.

On the other hand, training in the morning during a fasted state can actually be beneficial, as long as you don’t overdo it. Fasted training has been shown to improve metabolic adaptations and protein synthesis. (24, 25, 26)

5. Monitor Your Meds

If you’re on medications for chronic health issues, you may need to adjust the dose while practicing IF—which is usually a good thing! Please consult with your healthcare providers before jumping on the IF bandwagon. They can help you monitor your progress and alter meds as needed.

6. Take Special Considerations if You’re Female

Can women thrive on Paleo IF? Weight loss, blood pressure control, and increased insulin sensitivity are just a few of the benefits women can expect from a Paleo diet and lifestyle. (27, 28) But whether IF is a good idea for women in general isn’t a simple yes or no.

Women seem to be more sensitive to stressors like fasting and haven’t always fared as well as men in IF studies. (29, 30, 31, 32, 33) For example, three weeks of alternate-day fasting improved insulin sensitivity in men, but worsened glucose response to a meal in women. (34)

Whether a woman of fertile age is planning to get pregnant or not, her body always is. Pregnancy is a demanding long-term biological state with an enormous nutrient requirement. If stress is significant enough, a woman’s body will shut down fertility for fear of scarcity. If you’re trying to conceive, pregnant, or breastfeeding, this is not the time to give IF a try. Nutrition during pregnancy and during a child’s first two years of life affect their long-term health risks and outcomes. (35)

If you’re in good health, not pregnant or planning to be, and not breastfeeding, just be cautious when implementing Paleo IF. If your period stops, stop the IF. If you’re light-headed while fasting, stop. IF can be uncomfortable in the adjustment period, but it shouldn’t be tortuous.

IF Isn’t for Everyone

Everyone can benefit from eating a varied, nutrient-dense, Paleo diet, and many different varieties and templates exist to accommodate your individual needs. But IF isn’t necessarily for everyone. Aside from women who are trying to conceive, pregnant, or breastfeeding, you also may want to think twice about IF if you:

  • Are not getting enough sleep
  • Are underweight
  • Are a very lean woman
  • Are already insulin resistant
  • Have HPA axis dysregulation
  • Have severe hormonal imbalance issues
  • Have a thyroid condition
  • Have a chronic infection
  • Are suffering from a major life stressor

If IF does seem like a good fit for you, it can be a natural complement to your Paleo diet. Give it a try and remember to adjust as needed until you find the approach that works best for you.

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