How to trick your brain into eating healthy

All this might look like the bitter end for free will and food, but there could be a phoenix to rise from the ashes.

Neil Levy, a philosopher at Macquarie University and the University of Oxford, accepts the possibility of “determinism” – the view that every effect, including all human action, is preceded by a cause. If we knew every fact and physical law, we could predict human behaviour.

Some philosophers think determinism spells doom for free will because it means humans are nothing more than effete cogs in a clockwork universe. But Levy thinks that determinism, if it were true, is compatible with having free will. This is because even when we act without intention, we can still act according to reason.

Let’s say you’re waiting at a pedestrian crossing, headphones on, completely engrossed in a podcast on free will. The green man lights up and you make your way across. Deep in concentration, you don’t consciously register the green signal or a decision to walk.

But in Levy’s view you are still a free-willing agent if, somewhere in the past, the “rational you” has endorsed a green light as a sign to cross a road. Your decision to cross may be automatic, but it is executed as part of a considered game plan and is hardly random. Could the power of reasoning also salvage free will about food?

New research gives hope that it may, suggesting we can deploy rationality to change later unconscious responses to food cues. Take the example of “delay discounting”, an everyday fact of psychology that makes us downplay uncertain future rewards in favour of smaller rewards that are certain now. Obese people seem to have delay discounting amped up, attaching only a miserly value to the long-term benefits of weight loss compared to the sure-fire reward of food right now.

A 2013 study by Tinuke Daniel and colleagues published in Psychological Science shows how this might be countered. They had overweight adults vividly imagine a happy future event, like a romance or a party, while weighing up whether to take $10 now or $100 down the track.

Visualising a rosy future made the delayed reward more attractive. But the clincher came when they had people graze for 15 minutes on a smorgasbord while listening to an audio of their own descriptions of that happy future. They ate nearly 20% fewer calories than a control group.

Acceptance and commitment therapy uses mindfulness to help weight loss aspirants ‘surf’ the urge to eat and ‘ride the waves’ of inevitable hunger.

How it works is not entirely clear but Bärbel Knäuper, a psychologist at McGill University in Montreal, says “interventions that make an abstract future reward more concrete and bring it closer to the present have been shown to work”. 

This fits with findings that successful weight loss is often preceded by a triggering event, such as getting diabetes or not being able to fit into a wedding dress. These, too, may work by heightening the salience of the delayed rewards of weight loss. 

Knäuper argues that just saying “no” to the shortcake is much harder than planning to do something else altogether. She coaches her weight loss trial participants with “if-then” strategies such as “If I’m offered a sweet then I’ll opt for the salad instead”. This technique, developed by New York University’s Peter Gollwitzer, forges habits by associating the food cue with an alternative healthier response that carries its own reward.

A preventive strike on food cravings might also be launched with a relative newcomer to the world of psychotherapy. Acceptance and commitment therapy uses mindfulness to help weight loss aspirants “surf” the urge to eat and “ride the waves” of inevitable hunger.

And something on the horizon might just beat junk food advertisers at their own game. A 2015 study published in Appetite trained people to pair words such as pizza, chips and chocolate with unflattering monikers including sickness, fear and pain. Not only did participants develop more negative attitudes to those foods but a sub-group more easily tempted by unhealthy food ate less snack food afterwards.

Amid all the hope the University of Washington’s Michael Schwartz is circumspect and his message sobering: “It’s really very complicated. It’s very difficult to generate a cohesive, integrated explanation that unifies all the different perspectives that are out there.”

If anything is clear it is that human will is sandwiched between a yielding internal milieu and a world of eating cues that often just bypass consciousness.

Meanwhile, we might all heed late great psychologist B F Skinner’s closing, albeit gendered and enigmatically circular, words on the human predicament in Beyond Freedom and Dignity: “[Man] is indeed controlled by the environment, but we must remember it is an environment largely of his own making.”