I am Pavlov’s Dog (or, why we go nuts bingeing on junk when we are about to start a diet)

Dr. Jen Kerns

Dr. Jen Kerns

Back in August, when I was still in the throes of my passionate love-hate tryst with Sugar (which has been ongoing since Mother’s Day weekend!), I was shopping on an early Sunday morning at Trader Joe’s. I happened to be one day away from starting one of my quarterly DIY Fasting Mimicking Diets (FMD), which I’d planned for the following week, so I’d been planning on eating a very low carb diet that day in order to help me enter ketosis more quickly on the FMD. I passed around a corner, and displayed right there on the end of an aisle at eye level was a bag of peanut butter & jelly dark chocolate mini truffles. (Perfect positioning, TJs marketers!! I’ll write more about the food industry and how they manipulate us into buying more of their junk food in a future blog post.)

In a split second, my primitive brain — the one who wants me to overeat highly rewarding calorie-dense foods all the time — convinced me to pick up the bag and run. That tricky primitive brain even convinced my weakly protesting higher human brain that I would just eat one 3-piece serving of the chocolates and freeze the rest. And, they were organic, so… yeah, organic. Well, I’d eaten the whole bag (a total of 8 minis) by the time my car pulled into our driveway. Now, this was bad enough, but somehow my sugar addicted brain then felt waaay more cravings for sugar and processed carbs after I’d gotten that first hit, and you can imagine what happened. The rest of the day included bowls of Kashi cereal with honey (and I even reached into the jar with a finger and just scooped me up some straight honey!), pizza and Pringles for lunch (I don’t even LIKE Pringles!), pasta and a few glasses of wine for dinner, and some white chocolate pudding to top it all off.

It’s like my primitive brain knew we were going into a famine and wanted to overeat all the damn carbs in the universe beforehand to keep me from dying. I didn’t even eat yummy worthwhile sugar/flour, like a delicious handcrafted gelato or a beautiful pastry from a bakery. Not a single bit of it actually tasted delicious to me. I gained 3 pounds overnight from the crap, and I felt like crap. Obviously, even though I am incredibly knowledgeable about biology and medicine and why my body craves these foods and why they are terrible for me, my beastly Neanderthal brain doesn’t give a sh*t how smart I am.

Why did I — do we — do this to ourselves? Overeat junk like there’s no tomorrow right before starting a diet or lifestyle change?

Let me tell you a bit about conditioning. (Hang in there with me!) Remember Ivan Pavlov and his dogs? Pavlov won the Nobel prize in 1904 for his research in which he demonstrated that dogs can be conditioned to have a physical reaction – salivation – in response to the sound of a bell, because they learned to associate the sound of the bell with the presentation of food. This is called “classical conditioning,” when you learn to associate two stimuli with each other (the bell and the food), and have an involuntary response (salivation) to the new stimulus (the bell) even in the absence of the original stimulus (the food). Similarly, B.F. Skinner noted that in operant conditioning, an animal (or human) learns that when they DO something, a certain behavior, they either get rewarded with something positive or the removal of something negative, which reinforces the behavior, or they experience no response or even a punishment, which extinguishes the behavior. For example, if a lab rat gets a food pellet reward every time it pushes a button, it is conditioned to push that button and will keep doing so as long as the behavior continues to be reinforced with the reward. Interestingly, unpredictable intermittent rewards doled out randomly are even more reinforcing on a behavior than consistently predictable rewards, and produce behaviors that are more resistant to extinction: if you’ve ever seen a bleary-eyed gambling addict repeatedly pulling on the handle of a slot machine in Vegas, you’ve seen the power of random intermittent rewards on conditioning.

When the reward is suddenly stopped (e.g., the pellet dispenser gets jammed, which is what happened in B.F. Skinner’s lab), the rat will continue to press the button for quite a while without being rewarded until it eventually stops trying. This end to the behavior is called “extinction.” Interestingly, animals (and humans) sometimes even increase their behavior dramatically when the reward is initially removed in an effort to get it back. This is called an “extinction burst.” For example, if you are conditioned to expect that an elevator will take you to another floor and open its doors to let you out when you push a button, but one day you get on an elevator and it just sits there motionless after you press the button, you will try to push the button again. And again. And again. And then you’ll start pounding on the button more frantically, then maybe jamming on all the buttons, in an effort to get the response you want. If none of those efforts make the elevator go, eventually you’ll quit hitting buttons (extinction). That little button-pushing tantrum of yours was the extinction burst.

I believe this is what is happening when we lose it and pig out on junk food right as we are eliminating highly rewarding foods from our lives. At baseline, we feel an urge to eat junk and do so (the behavior), and are conditioned that we’ll feel lots of warm fuzzy feelings thanks to our friends dopamine and endorphins flooding our brain. (Or that the junk food will reward us by taking away the negative feelings we are experiencing, as in the classic pint of ice cream eaten in response to a breakup: this removal of a negative stimulus is called “negative reinforcement.”) Either way, our brain knows it’ll feel better when we eat that food. So our inner animal starts panicking at the prospect of losing that reward, and we then experience the extinction burst: bingeing on the junk that we’re trying to avoid. Certain foods are more highly rewarding than others, of course — no one ever freaked out at the prospect of not being able to eat okra again, but giving up sugar and flour (no chocolate? No bread? No pizza?) is a completely different ballgame. And by randomly/intermittently giving in and eating the food only sporadically when we are attempting to extinguish the eating behavior, we are likely inadvertently reinforcing it even more by following a variable reward schedule than if we just ate the food consistently all the time (remember that gambler at the slots?).

So, my complete carb binge the day before my FMD started was most certainly an extinction burst. I knew I was going off sugar and flour, and my brain was like, HELL NO and acted much worse than usual, eating all the carbs I could find in the house. I mean, who eats honey out of a jar with their finger when they are not even remotely hungry? Apparently I do when my inner beast is faced with the thought of losing sugar. We are animals, after all, and the smart way that my brilliant and capable human brain will have to tackle this sugar addiction is to treat myself like one: I need to create a hard stop on the reinforcing rewards that I keep giving myself and prepare myself for the inevitable extinction burst that my primitive brain is going to try to throw at me when I do it. I’ve created a situation in my body where I behave like a sugar addict. And my behavior of overeating sugar has become one that is extremely resistant to extinction because of my random intermittent reward schedule. When I avoid sugar for days or a week or two and then give in and have some, I feel intense cravings for it and usually eat way more than I intended. So, I believe that giving up sugar and flour entirely for at least 6 or 8 weeks at a minimum — feeling the craving and then failing to reward it over, and over, and over — is the only way to extinguish my urges and create inner peace around food (and reach my dream goal weight of 135). The intermittent slip-ups are only serving to make my desire stronger and keep my weight stagnant in the 140s. Here comes the extinction burst: my inner beast is screeching right now that I should go get some chocolate. And it’s deafening.

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