What I’ve Learned from Following Two Meals a Day for a Month

Update: I have a one-year follow-up post here and a two-year follow-up post here.

On July 24, 2022, I finished reading Mark Sisson’s and Brad Kearns’ recent book, Two Meals a Day: The Simple, Sustainable Strategy to Lose Fat, Reverse Aging, and Break Free from Diet Frustration Forever. This book delivered on its title and has helped me develop sustainable habits that have already shown positive results. Below I provide context on my situation and briefly summarize the results I’ve seen so far. Then I summarize the book’s main pieces of advice and then give an overall assessment of the program.

My situation

I should preface this post by emphasizing that I am not an elite athlete, nor have I ever participated in a marathon, triathlon, or Ironman. While I’d love to look like Chris Heria, building and maintaining that kind of a body is a full-time job that I don’t have time for.

My sole fitness goals are 1) to not become overweight; and 2) to prevent debilitation of my quality of life as I become older. My current fitness activities include chasing my kids around the house, doing light calisthenics (mostly inclined push-ups and inclined pull-ups) at various parks around my city, doing 5 minutes of yoga stretches most evenings, going on walks with my wife, playing pickup basketball once a week, and commuting to work by bicycle (4 miles each way) a handful of times each month.

While I am not much of an athlete, I have been doing intermittent fasting since late 2018. I started out doing a “16:8” (8-hour eating window, 16-hour fasting window) but then quickly and easily expanded that to 20:4 and eventually only eating one meal a day every day. I have done 48+ hour fasts a few times but haven’t had much success getting past 60 hours. I haven’t eaten breakfast more than 10 times in the past four years, and I haven’t missed it.

Early results

After reading the book, I was excited to make a number of different minor adjustments to my diet and exercise habits. Here are the main changes I made (keeping in mind that I was already fasting 18–22 hours every day):

• Walk at least 7,000 steps every day, no matter what.
• Don’t eat any of the junk foods that other members of my household eat. These include candy, sugar cereals, ice cream, and chips
• Eat whole foods (fresh produce, meat/fish)
• Eat fermented foods (so far, just Kefir — a sort of drinkable yogurt)
• Make sure I get enough electrolytes each day. I tried the supplement LMNT and liked it a lot but it’s very expensive so I think I’ve found a much cheaper alternative.
• Stay active throughout the workday by taking short breaks each hour to move my body in some way: go up and down a flight of stairs, do 10 pushups, do a short 5-minute yoga session, or do some squats or wall angels
• Intentionally park farther away from my office or stores I’ve driven to so that I am forced to do more walking
• Do a bit of cold exposure by turning the shower to the coldest setting for 1–2 minutes at the end of my shower

While these have mostly been minor adjustments to my lifestyle, the benefits have been rather stark. I’ve lost 10 pounds and I’m now back to the weight I was at the end of high school. 8 weeks ago, I had the beginnings of a spare tire that has since flattened out and allowed me to wear comfortably wear pants that I hadn’t been able to wear for two or three years.

More importantly, I feel like I can easily sustain these goals. Once I got some positive momentum, I wasn’t tempted when someone offered me a donut or when I saw one of my children was munching on Cheetos. The main challenge moving forward is social eating situations. Restaurants often don’t offer foods consistent with this diet, which can be inconvenient at times. And if I attend a birthday party or other social gathering at someone’s house I feel like I’m being rude if I don’t eat a little bit of the junk food that’s being offered.

While I have had some “cheat meals” (which have mainly arisen due to social obligations) I haven’t let them disrupt my rhythm. I’ve also found a good “dessert” — a square of 90% dark chocolate topped with nut butter — that satisfies my sugar cravings but isn’t harmful. I feel like I can easily continue this path indefinitely.

As with all adjustments to fitness and diet, it’s difficult to assess which elements are responsible for the improvements. As Miles Kimball writes, any deviation from the Standard American Diet is likely to improve things, so there may not be anything particularly special contained in this program.

So, what is the program?

The book is roughly divided into six parts:

1. How your body’s metabolism works and why counting calories is nonsense
2. Foods to avoid and foods to embrace
3. The importance of a 24/7 healthy lifestyle: sleeping well, eating well, being active, being social, and reducing stress-inducing digital distractions
4. Why and how to fast
5. How to exercise in a more sustainable way (basically, don’t do HIIT; do HIRT instead)
6. How to reset your psychology and environment to quickly and permanently implement these principles

If you are so inclined, you can also listen to Joe Rogan’s conversation with Mark Sisson. They start talking about the book at the 40-minute mark.

Metabolism

The single most useful thing I learned in this book is what I view as a reasonable theory of metabolism. In short, your body can use energy either from recently digested food or from fat stores. To prevent becoming overweight or obese (or to lose weight in the long run), you want to turn yourself into a “fat-burning beast,” as the authors put it. Much of the book is centered on how to achieve this through a combination of diet, exercise and other lifestyle changes. In particular, ditching processed foods and fasting will give you metabolic flexibility which means your body naturally and seamlessly transitions between energy sources (food vs. bodily stores). It will also give you metabolic efficiency which means you’ll be able to survive on many fewer calories.

In the view of this theory, calorie counting is useless because the amount of calories in a food doesn’t provide any information about whether that food improves or impairs the body’s ability to be metabolically flexible and metabolically efficient.

Foods to avoid

The book recommends avoiding “the big three” harmful foods: sugar, processed grains, and industrial seed oils. While the first two get lots of attention, I had never heard of seed oils being bad for you. (Seed oils are cooking oils that are derived from chemical processes. These include basically all oils in our food except for olive oil, coconut oil, and avocado oil.)

There is plenty of evidence showing that a diet of processed foods leads to unhealthy weight, blood pressure, and other biometric markers. My understanding of the scientific frontier is that no one has yet proven why processed foods are so unhealthy. As the article I just linked says, “[It’s] not clear what specific aspect of the ultra-processed foods affected people’s eating behavior and led them to gain weight.” It could be the case that some processed foods are actually OK. Thus, the rule mentioned above might be overly aggressive in throwing out some non-harmful foods.

Foods to embrace

The book recommends an “ancestral” diet consisting of four main food groups taken from the book Deep Nutrition: 1) fresh foods (fruits, vegetables, nuts, seeds); 2) fermented and sprouted foods; 3) bone-in meat; and 4) organ meats.

Lifestyle

The main lifestyle principle advocated by the book is that your health will spiral out of control if you constantly put yourself in a high-adrenaline/high-cortisol state. This is because when the body is in fight-or-flight mode, it will not use its resources optimally: the body is programmed to trade off short-term health status for protection from death.

The book discusses many details surrounding sleep, social interaction, and routines that I won’t get into here, but have a closer look if you think you’re struggling in these aspects. The one piece of advice that I appreciated here was to avoid overeating. The principle the authors suggest is to eat until you’re 80% full. I have come to realize that I’ve been consistently overeating (which is easy to do when I only eat one meal a day). Adjusting that has been a big part of my success. And it goes back to the “metabolic efficiency”: I thought I needed X number of calories to survive, but it turns out that my body has likely become more metabolically efficient over time, so my overeating was doing more harm than good.

Why and how to fast

The “why” of fasting goes back to the principles of metabolic flexibility and metabolic efficiency mentioned above. When you fast, you take away digested food as a potential energy source for the body. As a result, your body draws its energy from fat stores. This has many health benefits, including weight loss and forcing the body to become more metabolically flexible/efficient.

For the “how” of fasting, the authors put together a good program for easing a newbie into fasting. Given my experience, I didn’t learn too much here, other than the importance of maintaining electrolyte levels. Often when I fast, I have moments where I feel light headed or woozy. That’s because my electrolyte levels are too low. Making sure I have enough electrolytes has gone a long way towards improving how I feel while fasting.

Sustainable exercise

There were a number of helpful tips regarding sustainable exercise habits that I’ll briefly discuss here. The main theme of these tips is to get the body into “fat-burning mode” and to make sure you don’t over-train. Over-exercsing will put the body into fight-or-flight mode which will then cause the body to “liquidate its assets” (i.e. consume muscle for energy instead of fat)

• “Just [Freaking] Walk (JFW)” — walking is the best activity for turning on “fat-burning mode”
• Micro-workouts — if you have a desk job, make sure you take breaks often to keep moving (one of my favorite hacks here is to use a bathroom on a different floor)
• HIRT instead of HIIT — High-Intensity Interval Training (HIIT) is a great way to over-exercise. High-Intensity Repeat Training (HIRT) is the way to go
• Don’t liquidate your assets — Above all things, make sure you don’t get your body into fight-or-flight mode so that it doesn’t liquidate its assets (see here for Mayo Clinic’s endorsement of this idea)

Tips for quick and permanent implementation

The book spends a lot of time building up the reader’s psychology and behavioral habits so that transitioning to this program can be a success. At one point the authors even explicitly state [I’m paraphrasing], “we could fit all of the information you need onto one sheet of paper, but there’s no way you will actually do all of the things you need to without behavioral and psychological intervention.”

There are journaling exercises throughout the book and the last chapter is devoted to a 12-day challenge to supercharge transition to the new lifestyle.

My overall takeaway

As I mentioned at the beginning of this post, I am pleased with the new direction of my life.

On the plus side, many of the recommendations have been fairly easy for me to adopt and the results have been remarkable. Seeing positive results quickly has been fuel for staying on the trajectory.

On the negative side, I am unsure if my body will acclimate to these new behaviors and rebound back to my previous weight. This isn’t a critique of Two Meals A Day so much as it is a critique of any policy that results in weight loss.

I definitely recommend this program to any and all who are medically cleared to take it on! I believe almost everyone will be able to take something from this program that is easy for them to adopt and use it to make positive changes in their life.