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Why Diet Myths Are So Hard to Shake

Note: the following is based on my understanding and interpretation of what I read in The Believing Brain – the author did not discuss diets or food-related issues in the book.

I just finished a fascinating book called The Believing Brain by Michael Shermer, which talks about how and why we believe things – including spiritual beliefs, politics, and more.

The basic premise of the book is that we decide what to believe first and then look for explanations for those beliefs. We do this instead of evaluating all the information and then deciding what to believe. Shermer also talked about how several biases support our beliefs.

This idea wasn’t completely new to me. After all, in the Am I Hungry? Mindful Eating program, we talk about the TFAR cycle, how thoughts and beliefs (T) influence our feelings (T), which in turn impacts our actions(A), and how the results of those actions reinforce the initial thought or belief (R).

But Shermer went into the topic much more deeply and reading his analysis gave me additional insight into why it can be so hard to shake the diet mentality.

3 cyclic diet myths

Consider the basic cycle that drives diet culture, which involves three myths that feed into each other:

  1. I need to lose weight to be healthy and/or attractive

  2. Dieting is the way to lose weight

  3. If I don’t lose weight, or I gain it back, I’m at fault, not the diet – so I should try again or try another diet

Many believe these myths for several reasons.

Myth #1: I need to lose weight to be healthy and/or attractive

If you believe this, it’s not hard to see why because it’s supported by popular culture and many biases.

First, consider that many doctors will tell you to lose weight, often without even looking at other aspects of your health. The authority bias makes it easy to believe them – this bias is when you value the opinion of an authority figure. The doctor, after all, has studied medicine and treated lots of people. Why wouldn’t you believe them?

Except that doctors, too, are subject to bias, including confirmation bias, which is when you only look at evidence that supports what you believe and discount anything that goes against your belief.

So it may be worth trying to set aside the authority bias, particularly when many other studies show that dieting can negatively impact your health due to weight cycling and that you can be healthy while still being heavy.

Unfortunately, doctors aren’t the only ones telling you to lose weight. Almost everything in popular culture suggests that only thin people can be attractive.

All of this makes it very easy to fall into the bandwagon effect, which is “the tendency to hold beliefs that other people in your social group hold because of the social reinforcement provided.” (p. 274)

This ignores the fact that beauty is very individual and attraction isn’t all about weight.

Still, with so many people saying that weight loss is the only way to become healthy and attractive, it’s all too easy to believe this myth, which leads right into the next one.

Myth 2: Dieting is the way to lose weight

Once you believe that you need to lose weight, then it makes sense that you would look for a way to do that – and you’d turn to diets.

Authority bias can play into this as well, sometimes with doctors, but also with people like Oprah telling you to try weight loss programs.

Plus, diets give you the illusion of control – “the tendency for people to believe that they can control or at least influence outcomes that most people cannot control or influence.” (p. 275)

And it is an illusion. Genetic factors that are outside of our control determine much about our weight. Biology also works against us. Human bodies like to stay around the same weight, even if it’s a higher weight than what you might like.

Confirmation bias comes up again here as well since you’re likely to look for examples of people who’ve lost weight on the diet and ignore the people who don’t lose weight. You might also choose not to see if the people who lost weight initially gained any of the weight back because you don’t want that information. You want confirmation that the diet will work as you hope it will.

Given all that, it’s no surprise that if you believe that you need to lose weight, you’ll believe that you need to try a diet. But the results will likely not be what you hoped, which brings me to the third myth.

Myth 3: If I don’t lose weight, or I gain it back, I’m at fault, not the diet – so I should try again or try another diet

After you accept the idea that diets are the way to lose weight, and you’ve found all kinds of evidence that the diet works (due to confirmation bias), it’s no surprise that if the diet doesn’t work as expected, you choose to believe it’s your fault.

After all, if other people have succeeded with the diet, then the diet itself must work, right?

This is also what society tells people, that if you’re heavy, it’s because you’re lazy… have no self-control… sit on the couch all day and eat junk food.

You may even believe this about yourself before trying to diet. If you’ve gained weight, you probably go into the diet thinking that you have poor willpower. Even if you swear that this time you’ll really try and control yourself, that little voice in the back of your head will be whispering that you don’t have what it takes.

That can turn into a self-fulfilling prophecy – “the tendency to believe in ideas and to behave in ways that conform to expectations for beliefs and actions.” (p. 275)

If you’re lazy and don’t have any willpower, then of course you’ll fail the diet, and it has nothing to do with the diet, it’s only about you – right?

That, at least, is what many people believe, which is why it’s so easy to try another diet – and another – and another. You keep hoping that this time you’ll get it right, without questioning the diets themselves.

Getting free from the diet mythology

While it can be hard to change what you believe, it’s possible. So if all of this sounds familiar, here are a few tips to help you get out of that diet mindset.

1: Focus on health not weight

The first thing you can do is stop reading things that equate health and size. Instead, look for studies and evidence of people who are heavy but also healthy. Health at Every Size can be a good starting point.

Additionally, pay attention to your own health instead of weight. If you like paying attention to numbers, you could check your blood pressure or cholesterol, or see if you can increase your walking speed (while avoiding injury) or how far you walk (or other activity of choice).

Paying attention to these things instead of the numbers on a scale will help you get away from a weight focus.

2: Don’t discuss weight and diets with others

You may well have friends and family who are on the diet bandwagon and who like to talk about it all the time. Maybe in the past you’ve joined in, but it’s time to change that.

Request that they don’t discuss weight or diets with you. Find other subjects to talk about. You don’t have to talk about mindful eating or start venting about the diet industry, but as long as you’re around people who keep the focus on losing weight and trying diets, it will be very hard for you to get out of that mindset.

3: Change your thoughts

And instead of trying to change your weight, focus on something much more within your control – your thoughts.

As I mentioned, one of the attractions of diets is that they give you the illusion of control, but that can backfire when the illusion fades away and you realize that you were trying to change something outside of your control.

At the same time, one of the people Shermer talked to pointed out that “feelings of control are essential to our well-being.” (p. 80)

Since that’s the case, you’d do much better to focus on your thoughts since those are within your control, and if you can change those, and adjust what you believe, you’ll act differently and get more of the results you want.

Changing your thoughts isn’t easy, so start small. Maybe you could set a goal for yourself to reframe your thoughts every time the little voice in your head says that you’re lazy.

You can point to all the times you’re not lazy, and reframe the thought to be that you’re a moderately active person. If you tell yourself that often enough, you’ll start behaving in ways that prove it, and that will reinforce the thought and belief.

Beliefs drive more than you think

You may not consider your beliefs much, but they’re always in the back of your mind, and they influence what you do every day, in ways you’re not even aware of.

This includes diet beliefs. They’re very pervasive, and that makes it all too easy to fall into the trap of thinking those beliefs are truths. But they’re not – they’re myths.

To break free of the diet cycle, it’s important to first recognize the diet beliefs for what they are. Then you can look for evidence to remind you of why diets don’t work and why it’s better to focus on health instead of weight. And if you can change how you think about diets and weight, you’ll be much happier than if you kept on with the diet myth cycle.


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