I received an email today from Kahn Academy with the subject line Why New Year’s Resolutions are broken. The explanation (if you can call it that) in the message was that most people break their resolutions by February, so why not commit to completing an online course in January?

Cute. But it did get me thinking about why we break our New Year’s resolutions, especially resolutions to lose weight. I had quite a glorious career as a resolution-breaker back in the day, and I have the paperwork to prove it. From about age 25 all the way up until my daughters and Fat Head came along, I kept a daily journal. That journal is filled with optimistic resolutions committed to paper in January, followed by self-recriminations and occasional self-loathing around April or May. Lather, rinse, and repeat the next year.

Twenty-some years ago, I was on a comedy tour that ran through Iowa and Nebraska. I was also on a New-Year’s-resolution diet. The headliner, who happened to be one of those lean-jock types who’d never been fat a day in his life, rang my room at our hotel in Iowa and asked if I wanted to go out for lunch.

“Thanks, but I can’t do it. I’m on the Slim-Fast diet.”

“Really? You’re living on those little shakes?”

“Yeah, I need to lose 25, maybe 30 pounds.”

“Well, I guess that keeps the food bill down when you’re on the road.”

The show was at a nightclub just off a two-lane highway in the middle of nowhere. As I parked in the nearly-empty lot an hour or so before the show, I wondered what kind of crowd they could possibly draw. The answer was: a great crowd. An awesome crowd. A packed-house crowd that cheered wildly when I finished my set and turned the stage over to the headliner. Man, I thought, they must get everyone who lives within 40 miles to show up for comedy night.

I went to the bar, intending to order a Diet Coke.

“You want a beer?” the bartender asked. “It’s on the house for the comedians.”

“Uh … sure. I’ll have a Miller Lite.” I was on a diet, after all. A light beer couldn’t hurt.

The second one didn’t hurt either. The third tasted awesome – and I don’t even like light beer. But man, was I craving that third one. I craved a fourth one after that, but stopped myself from ordering it. I was on a diet, after all.

I’d been aware of being hungry before my set, but sometime after finishing that third beer, I felt downright ravenous. Chew-the-furniture ravenous. As if reading my mind, the bartender walked over with a pepperoni pizza and set it in front of me.

“Here, you can have this. Somebody screwed up the order in the kitchen. We can’t sell it.”

Just tell him thanks but no thanks, I thought to myself. You’re on a diet. All you’ve had so far are three light beers with 100 calories each. No harm, no foul. You don’t really want this greasy pizza. Nothing tastes as good as thin feels, right?

Wrong. The pizza tasted fantastic – and I don’t usually order pepperoni on my pizzas. As soon as I took the first bite, my brain was screaming for the next one. And the next one. And the next one.

So there I was, stuffing my face with pizza when the headliner finished his set and came to the bar to get a drink. He didn’t say anything about me breaking my Slim-Fast diet. He didn’t have to. I saw him glance down at the pizza and then up at me, and he seemed to grimace just a wee bit. I interpreted his expression as You poor, weak-willed slob – mostly, of course, because that’s what I was thinking about myself.

In other words, I thought my failure to stick to a weight-loss diet (by no means my first or last failure) was caused by a flaw in my character. I was fat because I was mentally weak. I just need more willpower, more determination. I told myself that over and over, year in and year out. My old journals are full of admonishments along the lines of “Why do I keep doing this to myself? How many times am I going to start over on Monday and blow it again by Friday?”

Here’s a specific example from an entry in March 1997:

I worked on the play, then ate an entire pizza while watching King of the Hill and the X-Files. Why? Why do I do this? What gets inside of me and says, “You’re losing weight, you’re working out– it’s time to @#$% that up! Let’s undo all that progress!”

Well, I had the right idea as far as the problem being inside of me. But it wasn’t about character. It was about chemistry. Let’s revisit my comedy road-trip in Iowa and think in terms of what was happening at a biochemical level.

Back in those days, I was still mostly a vegetarian. I’d eat a little chicken or fish now and then when I went out for dinner, but I didn’t eat meat at all at home. (Most of those pizzas I downed were topped with spinach, mushrooms and onions.) I pretty much lived on cereal, fruit, vegetables, rice, pasta and potatoes. In other words, I’d conditioned myself to depend on regular infusions of glucose to provide fuel for my body and brain. And given how slowly I lost weight when I managed to stick with a calorie-restricted diet for a month or two, I obviously wasn’t very efficient at tapping my body fat for fuel.

Slim-Fast is nothing more than a can of liquid sugar with a wee bit of sunflower oil and milk protein tossed in. So whenever I went on a Slim-Fast diet, I was continuing to live on glucose, but far less of it than I was used to. The burst of simple sugar no doubt spiked my glucose, and then my body responded by releasing insulin to beat it back down. I remember often feeling shaky two hours after those Slim-Fast meals – it was low blood sugar, of course, but I couldn’t raise it with another meal or snack because I was on a diet.

When I walked into that nightclub in Iowa, I probably already had low blood sugar, thanks to the Slim-Fast meals. Fortunately for my performance, hearing an emcee announce my name always produced a burst of adrenaline, and adrenaline releases glucose from glycogen stores while simultaneously stimulating the release of fatty acids from adipose tissues. My brain had fuel for the show. But when I was finished with my set and the adrenaline rush was over, my blood sugar was probably falling again.

No wonder those Miller Lites tasted so darned good. Alcohol is fuel. As I topped up the fuel tank, my brain was happy. Unfortunately, alcohol is a quick-burn fuel, and after living on something like 600 calories of Slim-Fast all day, I’m sure I burned through it at a record rate. I not only ran short of fuel again, I was almost certainly shorter on fuel than before. Among its many other effects, alcohol suppresses the liver’s ability to convert glycogen to glucose. So as the alcohol burned away, my brain was starting to experience a full-scale fuel emergency. On a diet consisting mostly of sugar, it’s certainly not as if I was producing ketones to provide an alternate brain fuel.

That’s why I was ravenously hungry when the friendly bartender set a pizza I didn’t order in front of me. That’s why as soon as I looked at it and caught that pizza aroma, my brain was screaming “@#$% YOUR STUPID DIET! FEED ME NOW!”

And so I did. It wasn’t a matter of character. It was a matter of chemistry.

How many times have you (or someone you know) stuck to a calorie-restricted diet for a couple of weeks, had a few drinks at a party, then headed to a Denny’s for a massive meal? The usual explanation – which I bought into for years – is that the alcohol affected the part of the brain that controls discipline and inhibitions, so the dieter’s inner hedonist took over and decided to make a pig of itself. In other words, the alcohol unleashed a character flaw that had previously been manacled by conscious willpower.

Wrong. By suppressing the conversion of glycogen to glucose, the alcohol produced a low-blood-sugar emergency — in a body already on the verge of a fuel shortage because of a restrictive diet. The body and brain then responded with a series of biochemical reactions that triggered a ravenous appetite. The brain wasn’t being a bad boy because its noble half got drunk and fell asleep. It was protecting itself from a dangerous fuel shortage.

That’s also what was happening when I’d semi-starve myself for a week, living on microwave meals consisting of pasta with fat-free marinara sauce, then end up ordering a pizza and eating the whole thing. I couldn’t stick to the low-fat, low-calorie diets I tried over and over because they took me on blood-sugar roller-coaster rides my brain couldn’t tolerate.

I could tolerate a high-calorie, high-carb, low-fat diet and often did … but that diet created other problems which, at the time, also looked like character flaws to me. Gaining a little more weight every year was one. An explosive temper when my glucose was falling and my adrenaline was rising in response was another. Drinking too much was another.

I wrote about the drinking problem when I reviewed Nora Gedgaudas’ excellent book Primal Body, Primal Mind in a post nearly four years ago. Here’s what she wrote about alcoholics in that book:

Alcoholics are utterly dependent upon and regularly seek fast sources of sugar – alcohol being the fastest … the problem in alcoholism, in fact, really isn’t alcohol per se, but severe carbohydrate addiction … Once cravings for carbohydrates and dependence on carbohydrates as the primary source of fuel are eliminated, so are the alcohol cravings. Training the body to depend upon ketones rather than sugar for fuel is key to this equation.

As I recounted in that post, when I stopped living on a diet that had turned me into a sugar-burner and became a fat-burner instead, I also stopped craving alcohol. Sure, I’ll cut loose on vacation, I’ll cut loose on my birthday, but then it stops. During most weeks now, I have two beers on Saturday night when we go out to a local Mexican diner we like, and that’s it. Unlike 20 years ago, drinking those two beers doesn’t trigger a desire for six or eight or ten more. It’s not a matter of discipline; it takes no discipline to turn down something you don’t particularly want. My character didn’t change. My chemistry did.

So coming all the way back around to topic of the post, why do we break our New Year’s resolutions? Why will sales of Lean Cuisine and Weight Watchers meals spike for the next couple of months, then flatten out again? Why was the gym packed when I worked out yesterday but will almost certainly be back to half-empty by April?

Our weight-loss resolutions fail because we keep trying to change our character. But character isn’t creating the problem. Chemistry is. When we try to overpower chemistry with the strength of our character, chemistry will eventually win. And that’s why so many grand plans to shrink our waistlines — from the ones imposed on us by The Anointed in government all the way down to the ones we resolve to impose on ourselves — are doomed to fail.

More on that in a later post.