Does What Time You Eat Matter?

Biology says one thing, psychology says another

Mar 16, 2023

I hope you all got some great ideas from last week’s newsletter about the Misogis you submitted. If you missed the email, you can download the complete list here: The Ultimate Misogi List.pdf

Remember: Make it hard, don’t die.

One thing that came out of the recent 2% reader poll is that many of you would like more nutrition information. I’m not shocked.

Humans evolved to eat more food rather than less and prefer calorie-dense food. This helped us survive in the past when food was scarcer. But our food drives often backfire in a world that is now filled with readily available food that is more calorie-packed than anything our ancestors could have ever dreamed of.

This is a “good problem.” Having too much food is far better than not enough; starvation will kill you quicker than diabetes. But it’s a problem nonetheless, with (over)nutrition being the primary driver of our massive rates of chronic diseases like heart disease and diabetes.

Hence, scientists are researching all sorts of tactics that might help us eat in a way that improves our health.

One of these is called “chrononutrition,” a fancy word for investigating whether we should eat more food in the morning or evening. It leans into the idea that we have a sort of internal clock called “circadian rhythms,” where our bodies are best suited to perform certain duties at specific times.

The chrononutrition scientists believe that when we eat does indeed matter. And the field has gotten lots of hype lately, with big stories in the Washington Post and New York Times.

But the takeaways of the research and the popular stories about it often clash with real life. And if we follow those takeaways, we could end up worse off.

Today we’ll unpack this. We’re going down a bit of a rabbit hole. If you don’t feel like exploring all its caverns and just want some actionable advice about how to smartly navigate our (amazing but treacherous) food environment, scroll to the bottom and see the Takeaways section.

Big Breakfast vs. Big Dinner

The chrononutrition field is finding that eating a bigger breakfast is better. This seems to be because our metabolisms are more powerful in the morning. But how much more powerful?

A new, very-hyped piece of research in Obesity Reviews looked into just that. It analyzed nine different studies and found that people who ate a bigger breakfast and smaller dinner lost more weight on average than people who did the opposite. It also found that the bigger breakfast group had more significant improvements in their blood sugar, cholesterol levels, and insulin sensitivity. Those are markers for diabetes and heart disease risk. The Washington Post said the study’s takeaway is that it’s likely “optimal” for weight and health to eat a big breakfast, modest lunch, and small dinner.

But if you peel back the layers of the study—and I did—you’ll find that the effect wasn’t a grand slam. It was a slight edge.

Of the nine studies the researchers analyzed, five of them showed that big breakfast eaters lost more weight. Four found no real difference.

The same happened with those markers for disease. Roughly half of the studies showed the breakfast group had greater improvements in their disease markers. The other half didn’t.

And the thing we must always remembers with markers is this: they tell us about risk for disease, but they don’t confirm actual disease.

Markers like blood sugar, cholesterol levels, and insulin sensitivity are all related to diabetes and heart disease risk. But most studies don’t look at whether participants actually become diabetic or keel over from heart disease. Just because any given health marker moves slightly in one direction or another doesn’t mean we’ll be affected—especially if that health marker doesn’t get too high.

One Upside of This (Sort of Flawed) Research

Hunger sucks! And in most of the studies, the participants who ate a smaller breakfast were hungrier throughout the day. The same was found in another recent study.

This isn’t surprising—but it is helpful for people who struggle with hunger.

Eating more food earlier in the day will lead you to be hungry for fewer waking hours. On the flip side, eating a tiny breakfast will lead you to be hungrier during more of your waking hours. Then, if you’re hungrier for more waking hours, you’ll be more likely to snack mindlessly.

Frequent snacking is associated with weight gain. Mostly because we tend to snack on stuff like pastries, chips, and other junk.

When Science Clashes With Life

I do believe the slight edge is real. It probably is “optimal” to eat a bigger breakfast and a smaller dinner. It might alter our metabolism and some chemicals in our bodies in a way that seems to be better for us. But to what degree that improves our life is guesswork. And there’s always a catch.

Life isn’t a study. Unlike those participants, we don’t get pre-prepared and pre-portioned meals, detailed instructions, and a discrete period where we commit to eating some low-effort plan provided by scientists.

In real life, when and how much we eat is heavily influenced by outside forces—culture, family, friends, work, etc.

I texted the great and wise Dr. Trevor Kashey about this. You’ll recognize his name from The Comfort Crisis. He is The Brain. He pointed out the following:

“People do social activities at night. And social activities often involve calories. Which means you have other rules to contend with. So the person in the lab coat might say, ‘eat a bigger breakfast.’ But the attractive person at the bar might say, ‘let’s have another drink.’ Or grandma might say, ‘I baked you cookies.’ Or your boss might say, ‘good work, I’m taking you out to lunch.’ And the attractive person, grandma, and your boss win. Then you end up eating far more than you planned for the day.”

You can eat a big breakfast and have all intentions to eat a smaller lunch and dinner. But life happens. Pair your big breakfast with a bigger-than-intended lunch or dinner, and you’ll end up overeating for the day.

All the research suggests that eating more calories than you burn in a day—no matter when you eat those calories—is the most powerful determinant of weight gain. When weight gets high enough, disease risk spikes.

Takeaways

So how do we use this information? It depends on your situation and goal. Here’s what I think:

If you regularly eat a large dinner with your family: Eat a smaller breakfast. This will help you not eat more calories than you burn in a day. More importantly, it won’t impact your family traditions, which are likely far better for your physical and mental health than food timing.

If you plan to eat dinner at a restaurant: Eat a smaller breakfast and/or lunch, or even skip breakfast or lunch. It’s tough to not overeat at restaurants, thanks to food being dressed in butter and salt (a shocking amount of restaurant dishes clock in at 2,000+ calories).

If you want to lose weight: Don’t worry about meal timing. Figure out how much you’re eating and what amount of food it will take you to reach your goal. Then eat that amount of food however is easiest for you. Easy wins over the long haul.

If you struggle with hunger throughout the day: Try eating a larger breakfast, modest lunch, and smaller dinner. Focus on foods with just one ingredient, like potatoes, meat, vegetables, etc. Research shows these are best at helping people feel full.

If you want to “optimize” your eating: First, define what optimal means to you. Let's assume it's "doing what most research suggests is best for health." In that case, figure out how much you’re eating and what amount of food it will take you to reach a goal (e.g., lose weight, gain weight, stay at the same weight). Then slowly shift more of your calories to the morning. There probably is some “there there” to it being beneficial to eat more of your calories in the morning.

If your goal is health: Eat mostly whole-ish foods in a way that keeps you at the weight you want to be at. Consider a smaller dinner. It may also be good for you to occasionally fast, going 12-16 hours without a meal.

If your goal is athletic performance: Eat food around your exercise. It’s probably best to have a meal within a couple of hours before and after your workout. Eat at least 0.6 grams of protein per pound of your bodyweight (e.g., a 150-pound person would eat at least 90 grams a day).

2% Top Two

My two favorite things this week:

A New Partnership

You’ll notice the 2% Newsletter has a new sponsor in addition to GORUCK. Welcome aboard, Momentous. Across my career reporting on health and fitness, I’ve seen some sketchy stuff from the supplement world. Vastly overhyped claims, using off-label ingredients, etc. Momentous is opposite of that. For years, the company quietly built a business by making a heavily researched and pure product sold mostly to professional sports and collegiate teams and the military. They even partnered with scientists like Andrew Huberman at Stanford to formulate their ingredients. Now they’re rapidly building out access to the average consumer. I.e., me and you. I do think certain supplements can help cover our nutritional bases and help us perform better. And I think Momentous is the best brand in the game. See what I use from them below.

A Trick For Getting Big Stuff Done

I wanted a dog when I was 10 years old. But the problem was that I was an only child in a single-parent home, and my mom worked often. This meant I would have to bear the entire burden of caring for the dog. To prepare me for the big commitment, my mom made me draw up and sign an extensive contract of everything I'd do to care for the dog daily. We're talking every detail.

It turns out my mom was something of a lay behavioral psychologist. My aforementioned friend Dr. Trevor Kashey recently pointed out something wise about contracts and how we can use them to get stuff done. "A tool overlooked because it sounds silly (even though it has a good bit of literature supporting it): Writing yourself a contract (and signing it)," he wrote. "This has variations, but the underlying machinery stays the same. It creates a platform for harder commitments." Try it—write yourself a contract around something you'd like to accomplish. Sign it. Thank Trevor afterward. The dog, by the way, lived to be 17.

One last thing: UNLV, where I’m a professor, is in the Women’s NCAA Basketball Tournament. Go Rebs.

Thanks for reading and I'll see you next week,

Michael