One of the most common problems I encounter in my audience is binge eating. This is also one of the most common concerns Noelle and I field for our podcast. Everybody wants to know: How do I stop?

I have written about overcoming binge eating at great length before. In the article Binge/Restrict: The Most Common Pattern of Overeating and How to Stop, for example, I argue that while most people think the solution to binge eating is simply to be disciplined enough to get over it, the answer is actually the opposite. The answer, I argue, is to allow yourself abundance. The answer, I argue, is lots of food. Once you stop restricting your diet, you no longer feel the deprivation and obsession that inevitably cause you to overeat later on.

I do still believe that this is one of the most important things you can do to overcome binge eating. But I would like to discuss here the great, biochemical heft behind these processes.

Because here’s the thing: as much as society (and you!) may call you undisciplined, stupid, lazy, gluttonous, fat, insert demoralizing adjective here, for bingeing on whatever kind of food has hooked you, it’s wrong. It’s just plain wrong. You’re up against a huge set of biological, habituated compulsions. Bingeing behavior has now been proven to have potent biological motivators. And you must know it. I believe — I hope — that as you know it, so you may forgive yourself. Then you may more easily walk the path of healing.

To that end, I am going to describe two separate studies. These were both done on rats, so of course we cannot assume they to apply to humans. But there are human analogues and other human studies (such as on the science of sugar addiction – a topic for another time), that indicate the models may well apply.

Study #1

Binge-Like Consumption of a Palatable Food Accelerates Habitual Control of Behavior and Is Dependent on Activation of the Dorsolateral Striatum

This study investigates the difference between constant, non-restricted access to palatable foods versus restricted access to palatable foods. It ends up revealing that just a few weeks of occasionally being exposed to bursts of sweetened milk cause rats to binge on it, as well as to maintain these eating habits even after the time restrictions have been taken away. It happens because of neural changes that have taken place during the “burst” period. These changes cause long-term habits to form.

Teri Furlong and colleagues at the University of Sydney gave rats a diet of either normal chow or chow plus sweetened condensed milk. The “normal chow” rats were the control group. The rats that received the sweetened milk were divided into two groups: half got milk all day every day, as much as they wanted. The other half got access to the sweet stuff for only two hours every day.

After five weeks, the scientists trained all of the rats to press levers. There were two levers: one for sweet sugar pellets and one for simple grain pellets. In the test, the animals feasted on one of the types of food (either the sugar or the grain) and then exposed to a lever. In the first scenario, rats saw the lever for food they hadn’t yet had. If they had eaten sugar, they got grain. If they had eaten grain, they got sugar. In this scenario, all the rats ate a lot of the new food. Tastebuds like variety.

In the second scenario, the rats were given access to levers for the food they had already eaten. So if they had eaten sugar, they got a lever for sugar, and if they had eaten grain, they got a lever for grain. And this is where things really get interesting: rats who had had constant access to the sweetened milk in the training phase ate to satiety. They stopped pressing the lever. They had no interest in either the grain or the sugar. But, rats who were only allowed access to the sweet milk for two hours a day (and for the rest of the day, as much unsweetened food as they wanted), responded differently. They kept pressing for grain, even though they were already full of grain, and they kept pressing for sugar, even though they were already full of sugar. They weren’t pushing these levers because they were hungry. They were pushing these levers because having restricted bouts of access to sweet foods rewired their brains.

Interestingly enough, the researchers found that the obsessive lever-pressing was associated with an area of the brain called the dorsolateral striatum–an area of the brain associated with habitual behaviors. The researchers therefore hypothesize that rats develop long-lasting bingeing behaviors because of the repetitive training they had from the easier phase of the study. In that phase, they simply learned that the sweet stuff was rarely available, so they stuffed their faces when they could. This imprinted in them a long term habit.

Importantly, chemicals injected into their brains that interfered with glutamate and dopamine activity in the dorsolateral striatum caused the bingeing behavior to stop.

Study #2

In this study, MM Hagan and DE Moss subjected rats to four different patterns of 12-week restriction-refeeding cycles. The animals were either food restricted–constantly on a diet–or restricted plus some free-access binge days. After 12 weeks all rats underwent a re-feed period.

There were four different groups of rats: 1) “normal diet” eating with normal chow in the refeed period, 2) cyclical restricted eating (bingeing) with normal chow in the refeed period, 3) “normal diet” eating with palatable food in the refeed period, and 4) cyclical restricted eating (bingeing) with palatable food in the refeed period.

The rats that ate the “diet  eating” consistently received 75% of their normal calorie intake. The rats with cyclical restricted eating went through 4 days of restriction of 75% of their normal intake, then two days of a refeed where they could eat ad libitum.

After 12 weeks of this kind of entrainment, the rats were given 3 tests: 1) 24 hour deprivation and chow feeding; 2) 24 hour deprivation then chow and cookie feeding; 3) spontaneous chow and cookie feeding.

In the first test, with 24 hour deprivation and chow feeding, the rats which had gone through restricted cycles of feeding (on both normal and sweet food) ate 10% more food than the control rats. Interestingly enough, the rats that had been conditioned on sweet food were not all that interested in the chow feeding, and actually ate 20% less chow than the control group.

In the second test, with 24 hour deprivation and cookie feeding, rats that had been in sweet restricted cycles ate almost 20% more food than the control group.

In the third test, in simple spontaneous feeding without a 24 hour deprivation window, rats conditioned by sweet foods ate more than rats on normal chow, regardless of whether they had been restricted or not. The rats who ate non palatable chow and were on normal “diets” were perfectly fine; the rats who had eaten sweets but were on a normal diet ate about 20% more; the rats who had been in restricted cycling patterns and refed on sweets ate 80% more than control mice on normal diets. 80% more. 

Researchers in this study conclude, therefore, that “of all the conditions, the restricted/palatable group showed the most bulimic-like eating behavior. That is, a history of restricted eating (dieting) and refeeding on palatable food (bingeing) predicted a persistence of bingeing-eating behavior even after a 30-day period of normalization.”

Other Studies and implications

Of course, these are just two studies, and have been conducted on rats. There are plenty of indicators that similar phenomena  are at play in human beings. Recall perhaps most strikingly of all the Minnesota semi-starvation experiment in which “normal men” were food restricted and showed binge eating and insatiable appetites for sweet foods even after many days of unrestricted eating during the rehabilitation phase (Franklin et al 1948). In the 90s, Polivy et al “found that uncontrollable bouts of binge eating were significantly more common among prisoners of WWII who had, over 50 years earlier, experienced severe food restriction compared with nonrestricted combat veterans” (1994).

Via experiments on rats, we can see more clearly mechanisms by which this takes place. Apparently, pleasure neurotransmitters (such as dopamine) are definitely involved, as are, to a significant extent, the parts of the brain that are associated with habit formation.

The bottom line is this: your history of dieting, of binge eating, of restricting and refeeding, has had a concrete affect on the functioning of your brain. I can’t tell you how many thousands of women have expressed terrible guilt and shame with respect to their bingeing behaviors. They are all incorrect. If you feel this way, you are also incorrect. Your biology compels you, and powerfully so.

As I indicated in the start of this post, literally the best thing you can do for yourself is to forgive yourself. Give yourself access to food, and unlimited. Accept your body and delight in how hard it tries for you. Provide it with the nourishment it needs to develop new habits. It may feel rough at first, but over time the body can actually learn to eat well. You may also find that staying away from sweets or certain palatable foods is important. So long as this does not cause you to develop obsessions with these foods, that could be good. It would remove the biological trigger of habit that you have imprinted in your brain. Even switching to a different set of palatable foods could help (so long as your access is unrestricted). They key here is developing a positive, loving, forgiving attitude and helping your body create new habits.

You may also wish to supplement with low doses of l-tyrosine and/or l-tryptophan. These are precursors to dopamine and serotonin, respectively. They have been demonstrated to sometimes be quite potent for curbing people’s compulsions to overeat (an argument famously made by Julia Ross in The Diet Cure). I have personally noticed that when I take L-tryptophan (I take it for sleep) my constant feeling of “I could eat” disappears, and I feel more like a “normal person.”

Do you have experience that lines up with what I’ve discussed here? Contradicts it? I’d love to hear about  what you’ve gone through, and anything you share could be a great help to someone else in the community.

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