Dietary Self-Regulation: Milkshakes and Dietary Restraint

In the first part of this series, we explored the general idea of linking the “more than you need” structure of an all-inclusive vacation with the “more than you’ve always convinced yourself you need” structure of successful recovery from a restrictive eating disorder.

In some little thought experiment digressions published on my website, I described the anorexic version of such a vacation (think nocturnal routines and lots of food hoarding), the pseudo-recovered version (full of “healthy eating/exercise” rules and plenty of body comparison) and the fully recovered blissed-out version that was my reality a few months ago.

You can do the thought experiment yourself, if you like: If you were to book a couple of Caribbean weeks for yourself tomorrow, what would your reality be like? What does that tell you about what you could be prioritizing right now?

Meanwhile, let’s take the next step in the self-regulation part of the argument. All-inclusive resorts give us one angle on what it means to make your own decisions: to self-regulate in ways not constrained by blindly applied rules. Some interesting experiments carried out in the 1970s gave us another. They investigated what “dietary restraint” (DR: using self-control to try to limit one’s food intake) does to people’s eating habits when they’re presented with something they like eating (ice cream) after they’ve already consumed a milkshake they wouldn’t normally.

The way DR survives—and is proliferating—as an approach to eating is that it promises you’ll eat less, or make better food choices, and so end up with a slimmer (read “better”) body. Anorexia nervosa (AN) is DR on steroids. AN gets you thin. And it keeps you not eating very much—until it doesn’t.

Many people diagnosed with AN progress to a bulimia nervosa at some point (and/or progressed to AN from something else), and transitions between diagnostic categories are common in many directions and at many phases of illness and life (Schaumberg et al., 2019).

Just as missing a meal often leads to later eating more than what you missed, so chronic restriction often leads to chronic over-eating—specifically in a way that feels out of control and may culminate in deliberate vomiting or other negation/compensation attempts. Of course, this leaves the others: the people who don’t shift from anorexia to any other eating disorder. They either have lifelong anorexia (which is not a victory for the human host), or they recover fully and permanently—a victory for the human and not for DR (or AN).

In the non-clinical context of people who exert higher or lower levels of dietary restraint, the same kind of picture emerges: restraint can not just be fragile, but create fragility. In Herman and Mack’s (1975) experiment, participants were asked to consume either no milkshakes, one chocolate milkshake, or one chocolate and one vanilla milkshake in a fake taste test acting as a pre-load.

Then everyone was presented with three tubs of ice cream (chocolate, vanilla, and strawberry) with another taste survey and invited to “taste” as much of each as they wanted in ten minutes, supposedly to provide accurate taste ratings. The researchers’ predictions were as follows:

subjects required to consume two milkshakes in addition to their daily quota of calories would be in a position of having exceeded the “permissible” limits of consumption for a restraint-governed daily intake. Normally restrained subjects might be expected temporarily to give up the attempt at restraint, once they had come to perceive themselves as having already “overeaten”.

If such subjects had not consumed a milkshake, their normal restraint would remain intact. Highly restrained subjects, then, were expected to consume more ice cream in the two-milkshake condition than in the zero-milkshake condition.

By contrast, subjects who are normally not restrained would not be “triggered” by the excessive milkshakes. Such subjects should behave internally, eating less ice cream after a larger milkshake preload. For both types of subjects, the one-milkshake preload was expected to have an intermediate effect. (p. 650)

The data were a strikingly good fit for the predictions. The researchers found that the low-restraint eaters would simply eat until they were full, whereas the high-restraint eaters who had already had either one or two milkshakes ate more ice cream than any of the others:

Quite clearly, the data conform strongly to the predicted interaction. High restraint subjects consume more ice cream after the milkshake preload than after no preload at all. Low restraint subjects consume decreasing amounts of ice cream as a function of the size of the preload. (p. 654)

One milkshake seemed to be enough to eliminate restraint in the high-DR participants, presumably through the “what the hell” disinhibition effect that leads to counter-regulation. The “dieters” who drank one or two milkshakes kept eating because they’d already failed by breaking the rule, so they might as well fail big. (This “what the hell” effect is the diet-specific version of the all-or-nothing fallacy so pervasive in eating-disordered forms of thought.)

All results controlled for “acute deprivation” by assessing time since the last eating and rough calories eaten then. And it’s worth noting that there was no difference between the “normal weight” and “obese” (>15 percent overweight) participants’ behaviour: The difference that makes a difference is the one between low “restraint” and high, or being a non-dieter or a dieter. So what we have is oscillation between extremes: from long (or not so long) periods of eating less than one would like to shorter periods of eating as much as one would like—which is a lot because the appetite is typically denied. The oscillation, by definition, precludes getting practice at existing in the middle ground of sensing and responding and adjusting without hard and fast top-down rules.

Self-Control Essential Reads

When Do People Think Abstinence or Moderation Is Better?

Buddha, Darwin, and Dumbledore: How to Override Our Impulses

The dietary restraint metric is hard to measure. Subsequent studies have suggested that the original DR scale may have been tapping a particular combination of high restraint and high susceptibility to disinhibition (Westenhoefer et al., 1994) or of restraint plus negative mood, which has been found to be associated with bingeing, purging, and generally more “disturbed” eating habits (Penas-Lledo et al., 2008).

In general, however, the restraint theory literature speaks to a recurring structural feature of what makes recovery from restrictive eating disorders hard: that withdrawal of rule-based restraint inevitably creates a self-regulation vacuum (at least temporarily), because that responsive middle ground is so unknown.

The middle ground was what used to appall me most about the idea of not being ill. Every day was that radical oscillation from nothing to a lot, but intentionally: fast all day, eat a large meal in the dead of night. I didn’t know how anyone could cope with the dullness of just messing around in the lowlands of neither very hungry nor very full, let alone tell me I ought to. I thought the long deep trough and the ecstatic peak were the best kinds of happiness on offer—or rather, I increasingly knew I hated it but didn’t believe anything else could be less bad.

Being well again is basically about existing in the dietary middle ground—which in turn, as I failed to realize back then, makes exploring the much more interesting extremes of other territories feasible (the highs and lows of love, sex, intellectual curiosity, professional ambition, aesthetic creativity, etc.). But crucially, recovery as the process that gets you here is not initially about inhabiting the middle ground.

I’ve written a bit before about how normality can be a slippery concept in recovery (and the more I think about it, the more misleading a guide it seems). One of the worst mistakes you can make at the start of the recovery process is to imagine that your task is to switch straight from an anorexic way of eating to a “normal” one.

Even if by normal you mean not statistically common but good and sustainable—the happily pragmatic way of eating that will sustain you for the rest of your life—you can’t get there directly because your body is incapable of self-regulating. After all, it’s had zero opportunity to do so as long as you’ve been ill.

In the next part of the series, we'll go on to explore what this mysterious ideal called self-regulation really is.