Carbohydrate confessions:
Stories (and data) from a low carb convert.


Have you ever been forced to change your mind? Even about something you thought was absolutely true? Well, that’s what happened to Dr. Spencer Nadolsky. A long-time low carb advocate, this high carb experiment rocked his world.

Like many recreational exercisers, or people who know at least a little about nutrition, Dr. Spencer Nadolsky was certain that his low carb diet was the secret to staying lean and healthy. Until he tried a high carb experiment… and the results astonished him.

In this article, we’ll share the results of his experiment. Even more, we’ll talk about how our assumptions can be challenged when we become our own guinea pigs, and follow the evidence of our experience.

Where nutritional rules get broken (maybe)

We all love being right. It feels good when the universe has clear rules.

If you’re a recreational exerciser or familiar with nutrition, one of the “dietary rules” you might “know” is that a low carb diet is “the magic secret” to staying lean and healthy. At the very least, you might have heard about the many benefits of a low carb diet.

Like Dr. Spencer Nadolsky, you might also have researched it. You might have trusted that nutritional wisdom so much that, like Spencer, you even recommended that everyone try it!

At one time, Spencer was so convinced of low carb diets’ value that he became a low carb promoter, appearing on podcasts and writing a popular blog to sing the praises of low carb eating.

Then he took up a new sport, and his coach persuaded him to try a higher carb diet.

The surprising result? His weight and health remained stable, while performance and energy skyrocketed.

His self-experiment proved his assumptions wrong. And in the face of new evidence, Spencer was forced to re-think his nutritional paradigm.

Darn you and your truth bombs, self-experimentation!

What this article covers

In this article, we’ll explore how self-experimentation can help you test nutritional theories and dietary “rules” on yourself, to see how your body responds.

But this article isn’t just about one guy’s journey. Or what’s “true”.

(That’s right, we’re not going to give you another “nutritional rule” to replace the “rule” that Spencer just apparently broke).

Instead, this article is also about the importance of having a critical, questioning, curious perspective. About not taking anything — not even what we say — at face value. About avoiding “one size fits all” rules and absolutes. And above all, trusting the evidence of your own unique body.

Who this article is for

If you’re a beginner who’s just learning about the basics of healthy eating, you might want to skip this article.

However, if you’re a little more advanced and have already tried various ways of eating, this piece may interest you.

You might also find this article valuable if you coach or educate others — for instance, if you’re a coach or fitness professional who might be advising clients on how to eat.

And finally, if you’re interested in self-experimentation, you’ll naturally want to find out about Spencer’s adventures and perhaps want to try something yourself!

Without further ado, here’s Spencer’s story, as told by the good doctor himself.

From high carb (big) to low carb (lean)

In college, I was an Academic All-American heavyweight wrestler — at one time, ranked third in the nation.  Unlike my smaller teammates who were always trying to stay lean to maintain their weight class, I was always trying to gain.

For me, bigger was better. And I ate big to stay big.

During that time, I packed down 4000-5000 calories a day. Lots of carbs from pasta, rice, and cereals.

But in 2007, I retired from the ring and decided it was time to get leaner and healthier.

So I did what a lot of people might have done at the time: low calorie, low carb.

I cut my calories down to 2500-3000 a day. And I cut out all carbohydrates that didn’t come from vegetables or fruit. Since I wasn’t going to be competing and practicing so much anymore, I figured I didn’t need those starchy carbohydrates to fuel myself.

Guess what? My strategy worked.

In the few short months before I entered medical school, I lost about 25-30 pounds. What’s more, I felt fantastic on my relatively low carbohydrate eating plan.

Before and after: Spencer dropped the carbs to go from 265 to 235 lbs.

The low carb years

Now, I’d studied nutrition. I knew that carbs are important. In fact, they’re our principal source of fuel, and crucial to virtually every system in our bodies. (To learn more, see All About Carbohydrates.)

Yet despite my knowledge and expertise,  I was one hundred percent convinced that a low carb diet was perfect for me.

The evidence seemed clear. I wasn’t getting a lot of activity besides weight lifting. I was easily staying lean. I seemed healthy.

So I figured low carb was a good choice.

Throughout the next six years, I ate an average of less than 150 grams of carbs per day — or roughly around 15% of my total calories.

Sure, once in a while I’d get more — at celebration times, dinners out, and so on. But most of the time, I kept my carbs lower.

Since I’m a doctor and love to geek out on this stuff, I did some very advanced blood testing to ensure my metabolic health wasn’t being hindered. According to those markers, everything looked terrific.

Well… almost everything. I was diagnosed with Hashimoto’s thyroiditis and subsequent hypothyroidism. But this seemed unconnected to my diet.

I felt great. I looked great. Best of all, I got to eat delicious food! All in all, my low carb diet seemed perfect for me.

What’s good for me is good for all… right?

It was easy to generalize my own apparently good results to others. Especially since the more I learned in my research and the more I saw in my clinical training, the better lower carb eating seemed.

Eventually, I became an eager advocate for the practice, appearing on podcasts, writing articles, and in general doing everything I could think of to sing the praises of low carb diets for everyone from couch potatoes to elite athletes.

The way I saw it, low carb eating promoted health and improved body composition for everyone.

So why wouldn’t I spread the word?

The low carb to higher carb experiment

Things might have gone on like this indefinitely, with me happily eating low carb, and happily preaching to the low carb choir.

But last summer my competitive itch came back. And as I started scouting around for my next challenge, a number of knowledgeable people suggested that I might be a good candidate for a bodybuilding competition. I decided to make that my next goal.

Now, as a PN advisor, I’m fully on board with the PN principle that everyone can benefit from mentors and coaches. So, once I’d decided to train for bodybuilding, I immediately hired one of the best natural bodybuilding coaches I could find.

You can guess what’s coming next.

I had to change my diet.

My coach asked me to switch from my lower carb, higher fat, moderate protein diet to a higher carb, lower fat, moderate protein diet.

He believed that the extra carbs would provide me with a little boost to maximize my workouts when my calories started to get low.

Ooops. Time to switch things up.

I can’t say I was all that eager to get started.

Keeping track

In order to get a baseline of what I was actually eating, I tracked my calories from the different macronutrients for several days. I then switched many of my calories from fat to carbohydrates. The charts show these changes.

(The first chart represents my typical low carb diet. The second represents my new high carb diet).



How did I make the changes?

I cut my fat down by:

  • going from my usual four breakfast eggs to one
  • cutting way back on bacon (*sob*)
  • no longer eating daily handfuls of nuts and frequent gobs of nut butter
  • choosing leaner red meats (a lot of sirloin)
  • getting a grip on my dark chocolate addiction, and
  • curtailing the blue cheese and olive oil combo that I liked to use on my salads. (I still use these, but in smaller portions.)

My new carbohydrate sources included:

  • oatmeal (a lot of it),
  • more fruit
  • rice
  • quinoa
  • potatoes
  • and even the occasional bowl of processed cereal – something that was forbidden on my old diet.

Quite a change.

Higher carb, higher risk?

Of course, I trusted my coach. But I’ll be honest — as a confirmed carbophobe, I hesitated to alter my diet so drastically.

I wasn’t increasing calories, so in theory, I knew that I shouldn’t gain any weight. Even so, given my assumptions about the superiority of my previous diet, I couldn’t help feeling a little nervous about getting… well… fat.

Meanwhile, potential weight gain wasn’t the only danger I worried about.

Some of my physician colleagues shared my views about the virtues of a low carb diet. And among them, rumor had it that eating high amounts of carbohydrates could change my cardio-metabolic health for the worse within a matter of days. Yes, days!

Specifically, they argued that a higher carb diet would cause my low-density lipoprotein particle numbers (aka LDL-P) to skyrocket.

According to this theory, eating a higher carb diet could actually put me at greater risk for heart disease.

No wonder some people (myself included) become carbophobes!

And no wonder I decided to continue with my advanced blood testing while I was on this higher carbohydrate diet. I wasn’t taking any chances.

About LDL-Cholesterol

LDL-C, or low density lipoprotein cholesterol is a measure of the cholesterol mass within LDL particles. Traditionally, LDL-C has been the marker used to assess a person’s risk of cardiovascular disease.

But LDL-C only provides an estimate of low-density lipoprotein levels. Studies suggest that the risk for atherosclerosis is actually more strongly related to the number of LDL particles (LDL-P) than to the total amount of cholesterol within the particles. That’s why a high LDL-P reading could be dangerous.

For more on cholesterol and why it is important to health, see All About Cholesterol.]

Some unexpected changes

My physician colleagues were right, in a way. Because within a week, I’d begun to experience some changes.

It’s just that those changes were not the ones they’d predicted.

First and most obvious were the “pumps” I started getting in the gym. This didn’t surprise me a whole lot; most fitness enthusiasts understand that fueling with carbs can provide a boost in performance.

A little more surprising, but still within the realm of what I’d anticipated, was my newfound ability to perform a set or two extra of the same exercise at the same intensity/weight.

For quite some time, I’d struggled to do this beyond the eight rep mark. Generally, I could go for four or five reps and then I would have to quit or cut back. So this was something new.

Meanwhile, in addition to these fairly predictable changes, there were a few unforeseen results.

First, instead of gaining weight quickly I actually lost about a pound and a half. Not only that, but even with that relatively minor weight loss, I was looking leaner and more vascular.

Second, all of my advanced metabolic markers improved, including glucose and lipid/lipoprotein metabolism labs. Talk about a shock!

When evidence meets dogma: The debate

After switching to a higher carb meal plan, I posted my initial weight loss results on Facebook.

That’s when the fun began.

Recall — at this point, I was pretty well known as a fan of low carb diets. And I’d gone on record, more than once, to argue for their benefits.

So within an hour, both low carb enthusiasts and pro carb enthusiasts began to speculate about what had happened.

The low carb promoters insisted that I must have lost muscle. After all, I couldn’t have lost fat with added carbohydrates! Especially since most people who increase carbs gain water weight due to the increased glycogen. Losing fat was an impossibility! (Except it wasn’t. Not according to the measurements.)

Meanwhile, those in favor of higher carb diets argued that my former low carb diet must have caused some subclinical hypothyroidism. On a higher carb diet, my thyroid was finally kicking into gear. And that, they believed, was why I’d been able to lose weight.

Ironically enough, as I mentioned earlier, I do have hypothyroidism caused by an autoimmune disease. But I keep close tabs on my symptoms and labs and these didn’t change. So a newly active thyroid wasn’t the explanation, either.

Mindfulness makes the difference

Until now, I haven’t said a lot about it, but I have my own theory as to why I lost fat despite adding carbohydrates.

Remember how I tracked my eating for a few days at the start of this change, and then switched my calories over from fat to carbohydrates?

Well, I believe that I subconsciously lowered my calories on those first few days. Quite simply, I was more aware of what I was eating.

Note: I wasn’t trying to eat differently than usual. On the contrary, I tried to eat the way I would on any other day. But when you write down what you’re eating, you automatically become more aware of the food you put in your mouth.

In the end, I think my baseline (around 2,700 calories per day) was on the lower end of what was normal for me (between 2,500 and 3,500 calories per day). So ultimately, it didn’t matter that I switched those calories from fats and protein to carbohydrates; as long as I maintained activity levels, I was going to lose weight regardless.

This would also explain the changes in my metabolic markers, because a hypocaloric (or lower calorie) diet will typically improve those as well.

Testing it out

To further test my hypothesis, I continued to monitor my progress over the next few months.

During this period, I wanted to gain a bit of weight before embarking on the long weight loss phase that precedes a bodybuilding competition.

Every day I weighed myself and tracked exactly what I was eating. Gradually, I increased my carbohydrate intake to around 400 grams of carbohydrates daily. And over the next four months, my weight steadily climbed.

As you can see in the chart below, after a few months of my high carb diet, I ended up at the same body weight. However, I had less body fat and more lean mass.

Starting measures Post weight gain Midway through weight loss
Weight 219 lbs 225 lbs 220 lbs
Body fat 9% 10% 8.5%
Lean mass 199.5 lbs 205 lbs 201.3 lbs

Right before the start of the weight loss phase, I underwent another set of advanced blood tests.

Guess what? The results were similar to my low carb baseline measures — which was exactly what I had expected.

Baseline After a week of low fat / high carb After period of weight gain
LDL Particle Number 1574 nmol/L 889 nmol/L 1421 nmol/L

(If you want to see all the numbers and track my contest preparation, visit my blog).

What have I learned?

Right now I am on my long descent to getting “shredded” (or super lean)  for my bodybuilding show. I am staying relatively high carb (over 300 grams of carbs daily), low fat (75 grams daily), and moderate protein (225 grams daily), while slowly losing fat. My workouts continue to be great.

Mindful eating makes the difference

But I need to emphasize that during this experiment, I have been weighing everything and tracking it in my journal. And I think this weighing and tracking are important.

In the past, I had tried adding carbohydrates to my diet freely. Surprise, surprise: This resulted in quick fat gain. Just what a carbophobe most fears!

But if you think about it for a minute, it’s obvious why I gained unwanted fat. In adding carbs, I  was simply adding calories — without looking at the whole context of my diet! Had I tracked what I was actually eating, I would have fared a whole lot better.

I suspect that a lot of people who try, and fail, with a higher carb diet, may be making the same mistake that I made in the past.

And if tracking is useful, it’s equally important to measure. If you’re anything like me, you find it a whole lot easier to guesstimate an appropriate serving size of apples or bananas than one of rice, pasta, or cereal — and you also find the rice, pasta, and cereals a whole lot easier to overeat.

And for low carb eaters, the same is true too. Bacon, avocado, nuts, and butter are delicious. And easy to over-eat.

That’s why if you’re trying to make any kind of physical change, no matter what diet you choose, I strongly recommend you measure and track your food for a little while.

Don’t make yourself crazy with it. But do make yourself more aware.

Later, once you have a fairly good idea of what a portion looks like, you can estimate using the PN method.

Higher carb or low carb… what’s right for you?

Does my success with a higher carb diet mean that I’ve completely turned my back on low carbohydrate diets? No.

Does it mean that you should immediately go face-down in a bowl of oatmeal? Not necessarily.

In fact, most of my new patients still get the low carb prescription. Why? Because if you’re inactive and overweight, it’s much easier to get your blood sugar and blood pressure controlled on a lower carb diet.

When I recommend a lower carb diet and ask patients to focus on lean proteins, veggies, and fruits, they automatically eat fewer calories and more protein. This makes them feel full for longer, which in turn helps them lose weight. By eating more vegetables, they also get more phytonutrients. They’re eating less processed food.

And altogether, this diet helps to rid them of the diabetes or hypertension that brought them to me in the first place.

But while low carb diets have their place, I no longer think they’re necessarily the right choice, or the only choice, for everyone. In fact, many of us might benefit from adding some healthy carbs to our diet. (To learn more, see Carb Controversy: Why Low Carb Diets Have Got It All Wrong.)

The fact is, restriction almost never works well over the long term. And most of us feel, look, and perform our best with a balanced diet that includes some lean protein, healthy fats, and quality carbs.

How to decide what could work for you

Your individual carb requirements depend on your:

  • goals (fat loss, muscle gain, maintenance)
  • genetics (different body types, medical conditions)
  • carb source (refined versus minimally processed)
  • activity level (sedentary, weight-training, endurance athlete).

And don’t just speculate on what you think you might need. Actually try it. Get some evidence.

Track and measure your intake; observe your workout performance and overall energy levels — heck, even get some bloodwork done if you’re willing to put your money where your quinoa-eating mouth is.

Gather data on yourself. Think of it as writing your Owner’s Manual.

What to do with all of this

If you’re a healthy exerciser whose blood sugar levels are normal and you’ve been eating low carb for a while, I recommend trying a higher carb diet. You might be surprised at the results.

And remember these simple guidelines:

  • Don’t overly restrict; don’t over-think it; don’t waste time with detailed “carb math.”
  • Enjoy a wide variety of minimally processed, whole and fresh foods.
  • Observe how you look, feel, and perform.
  • Decide what to do based on the data you collect about yourself, not on what you think you “should” do.
  • The only “rules” come from your body and your experience. Don’t follow a dietary prescription for anyone else’s body.

And above all, for most active people, carbs are your friend.

About the author

Dr. Spencer Nadolsky is the director of and a practicing physician in Virginia. His personal blog is

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