Why You Shouldn’t Trust Your Health Friends’ Advice
There is a lot of bad advice, bad science, and bad logic – and I’m sorry to report that some of it probably comes from people you trust. Sharpen your pencils and grab a seated Nonsense resistance School is in session.
In a sense, everyone is an expert about their own health: each of us knows what we are experiencing, what actions we are taking to change it, and how we feel as a result. So, if you’ve tried a certain diet and your knee pain is gone, you probably have a story about how the diet is gaining acceptance and will share it with anyone who asks.
But let’s turn it around. What if your knees hurt and your friend walks in to tell you if you’ve tried cutting out dairy? Even if they have a pretty compelling story, they’re still just one data point. Their experience is not proof that you will have the same experience.
Deep down, you know that. You won’t believe the news headline that says, “One Really Influential Person’s Decisive Scientific Study Reveals …”, well, anything. If you want to know if avoiding dairy products cures arthritis, or whether the MMR vaccine causes autism, or whether homeopathy can cure the common cold, you will need to get the opinion of many more people, even if it sounds pretty convincing.
But this person is your friend. You trust them. And you may have known them before and after they tried the magic diet and totally believe that they have improved. How could you go wrong in believing their stories?
Cognitive biases are to blame
We use labels in our thinking. This is not because we are lazy, but because we are smart. If we stopped to logically study and verify every information we came across, we would never get out of the bedroom in the morning. (Whether it actually 7 am? Am I that my house did not get picked up by a tornado in the night and dropped into such a city, looking?) So we put a lot of our thought processes on autopilot.
The strategies that keep us sane are our cognitive biases . They’re not bad, but we need to be aware of them to stop using them where they don’t help.
For example, confirmation bias means that when we have a mental model of how the world works, we try to fit new information into that model. If most things fit and some don’t, we reject outliers. So, if you wake up and see a tree branch right outside the window, where there was no tree branch before, you do not pay attention to it: maybe the wind has scattered some branches, or this tree has become taller, but you just don’t noticed before that it was visible from your window. You are not throwing away your model, which tells you that you are in your regular home in a regular backyard.
So if you have a girlfriend, name her Julie, who is generally pretty reliable, and you will stick with that assumption for as long as you can. If Julie says Emergen-C kept her from catching cold all last winter, you probably think she knows what she’s talking about. (If Julie were my friend, I could start a Google search for the evidence base for vitamin C, but we all don’t have the time or inclination to do this in every friendly conversation.)
Here are a few other biases that come into play: anchor bias , where we tend to believe the first thing we hear and compare everything else to that. Accessibility bias , where you are more likely to believe what happened to your friend than some statistic you’ve heard about people far away. There is the illusion of clustering where you want to infer a pattern from multiple data points – you may know three different people who say acupuncture cured their headaches. And don’t forget about choice bias when you feel obligated to defend the choices already made.
All of this affects how we perceive the advice of friends and look at our own experience. If you decide to skip some vaccines for your child, you can participate in discussions about this topic to explain why the choices you made are right for others.
What we miss because of our biases
The anecdotal evidence is extremely narrow: it gives us one opinion about the experience of one person trying to do something. We miss a lot when we rely on anecdotes. For instance:
Related Factors : Your friend cut calories and ate more vegetables, exercised more, and planned some “time for himself” to relax and sleep … but they believe it was the gluten-free diet that made them lose weight.
Placebo effects : If you try something, you want it to work, and you will interpret things in this light: also: “Maybe it helps?” and less “maybe it isn’t.” In a randomized controlled trial, when subjects are unaware of whether they are receiving treatment or a placebo, the effects can be objectively assessed. There is no way for your friend to step back and gain this objectivity.
Cause of the problem : If you have back pain due to a herniated disc, and I have back pain due to a stretched muscle, it doesn’t matter what I did with the pain. What worked for me may be completely wrong for you.
What happened to everyone else? Think of those weight loss ads that say “Atypical Results” in small print. Of all those who have tried the supplement they advertise, it is likely that most people have lost only a little or no weight at all. Maybe a group of people put on weight. But they pick the person who lost the most and build ads around him. Likewise, a friend of yours who says he got the flu after getting a flu shot is n’t showing typical results either.
Since there are these shortcomings in the anecdotes, we cannot draw reliable conclusions from them. Instead, it is important to look at science as a whole. A flu shot isn’t perfect, but the benefits outweigh the risks . Sometimes yoga can help with back pain , but it is not a panacea. The Whole30 Diet may help some people detect food allergies or sensitivities, but it is an unnecessarily complex way to do it .
Trust a friend, not his advice
We know that all of this puts you in a quandary. You don’t have to blur out “You are wrong!” every time someone asks if you have tried yoga.
So, trust your friend in his own feelings and experiences. If before they felt bad, and now they say that theirs is better, this is great! Congratulate and support them. After all, they know a lot about their feelings.
But this does not mean that you have to conclude that if yoga has helped them, it will help you too. Take their advice with a grain of salt: if you were interested in trying yoga anyway, it might encourage you to try it. And if you’re smart, you’ll skip this idea past your doctor or physical therapist to make sure you’re getting good advice from someone who really has experience.
If someone has a history of personal experience, and it is supported by research, proceed with particular caution. Someone can easily pick one study that confirms what they are saying, while ignoring tens or thousands of studies that say otherwise. This goes for almost all gurus who say their diet or approach is the only way to be healthy. They all cite research, and they all have conclusions that are inconsistent with each other. Review the statements by looking at sources you know are impartial.
Your assignment, if you decide to accept it: Find or remember an anecdote that sounded pretty convincing when you first heard it. Or, if you really want to challenge yourself, think about what you experienced and the lesson you learned from it. Review this experience or anecdote right now. Is it still that convincing? Why or why not? We will discuss it in the comments.