Is flexibility the key to lasting behaviour change, or is it just "restriction-lite"?

Flexibility in behaviour change has come up a lot in the reading I’ve been doing over the last couple of weeks. Some propose that the key to success in making health behaviour changes is to have plans and goals which are flexible, rather than rigid - that can adapt to whatever life throws at you. But is “flexible restraint” still just the same old restraint that we’re used to, just dressed up in a fancy coat?

All or nothing approaches and the “fuck it” effect

Those of you following me on Instagram may know that I’m currently reading The Joy Choice, a book by behavioural scientist and health coach Michelle Segar. I’ll be sharing a more detailed summary of my thoughts once I’ve finished it, but there’s a big theme in there that really resonated with me: the perfectionist, “all or nothing” approach we often take to health behaviour change. You know the one, it’s that “diet starts Monday” mentality, or deciding that if you can’t go for your planned 10K run, you might as well sit on the sofa and watch Netflix instead. I know that I myself have previously taken this “fuck it” approach: once I’d started to break the diet I was on, all hell would break loose and I’d eat everything in sight, abandoning my diet completely. Or, once I’d failed to stick to my planned programme of doing a specific exercise every day (usually because of a habit disruptor like a holiday or illness), I’d forget it all together and go back to doing nothing.

Michelle talks about how this is rooted in dichotomous “all or nothing” thinking, a cognitive distortion which is unhelpful to us. We make very rigid plans about eating and exercise, which are ultimately unsustainable (especially when they come up against the “real life” of work, parenting, or even just our fluctuating energy levels). Our response is often to berate ourselves for not having enough self-control, but this isn’t the solution: it just shackles us to this perfectionist thinking, making us feel like we’re not good enough.

Flexibility as a remedy

Michelle also talks about flexibility being part of the key to solving this: when our plans encounter a “conflict point” (i.e., something in real life which makes them more difficult), we can instead think flexibly about what other choices we could make. For example, instead of that 10K run which you might no longer have time for, going for a shorter run, or dancing round your kitchen instead (which is often my movement of choice 😂)

This flexible approach also emerges in other parts of the behavioural science literature, for example, in the suggestion that goal setting for physical activity should be flexible to a person’s life, and be able to adapt to other priorities (e.g. family, work). Some evidence suggests that being flexible about your diet (e.g. eating smaller portions, if you overeat at one meal, eating less at the next meal) is better than being very rigid about your diet (e.g. having a very explicit meal plan, counting calories, skipping meals). 

I can see how this could work for physical activity: flexing your goals to adapt around the other things going on in your life may help you to stay somewhat active, rather than not at all active. For example, I’m currently aiming to do 4x 30 minute pilates sessions every week, but some days I don’t have enough time or energy - I acknowledge this and either do just 5-10 minutes, or accept that some days it doesn’t happen, and I’ll be back at it when I can. 

However, when it comes to eating behaviour, this feels dangerously close to a “Do Diet”: “a healthy eating discourse that reframes dietary restrictions as positive choices, while maintaining an emphasis on body discipline, expert knowledge, and self-control” (Cairns & Johnstone 2015). Essentially, we might be being more flexible, but we’re still making decisions about what we eat based on external factors (i.e. what you “should” do), as a way to control our bodies, rather than trusting and listening to them. It feels like the “I’m not on a diet, I’m just trying to eat more healthily” diet (which, spoiler alert, is still a diet).

Flexibility vs. intuition

This great paper by Tracy Tylka explored this more deeply - looking at both this “flexible dietary control” and intuitive eating (which you can read more about in this previous post). She found that flexible dietary control actually can’t really be separated from rigid dietary control: i.e., if you’re restricting what you’re eating, it’s very difficult to do this purely in a “positive” and flexible way, without the very rigid type of restriction also creeping in. Dietary control also didn’t have the same positive associations with psychological wellbeing and BMI that intuitive eating did. BMI isn’t an outcome that I personally care about (and I’m very aware that it’s generally a terrible measure), but it’s interesting that often restrictive and controlling diets are often imposed with the purpose of reducing BMI, when actually, they could be have no effect, or even increasing it. 

However, we can’t be confident that adopting intuitive eating causes people to be healthier and slimmer. Most of the studies in the intuitive eating space are cross-sectional - i.e., they measured different things at one point in time and compared them. What that means is that we can’t truly say that intuitive eating is causing lowered BMI or improved psychological wellbeing, but we do know that it’s correlated with it (i.e., when people are doing more intuitive eating, they also tend to be happier and of a lower weight). So, either:

1. people who eat intuitively do better as a result, OR 
2. people who are naturally thinner and happier are more likely to be eating intuitively, OR 
3. some other thing is driving both things (maybe they just naturally have a lower appetite?)

So what’s the answer?

I suspect that flexibility is an important part of a weight-neutral approach to behaviour change. However, we need to be really careful about how we use it: if that flexibility is still grounded in external “shoulds” rather than what we truly want to do, we’ll likely just fall off the wagon in that “all or nothing”  way once again. 

What do you think? Do you often fall prey to “all or nothing” thinking? Or can you be flexible about your eating and exercise? Let me know in the comments!