The Benefit Of Exercise Is Just A Placebo?

You can't force your body to change. I address this in the episode What It Means To “Actually Train”. In short, what you can do is choose to introduce circumstances to which the body must adapt. The body, in turn, does what it does. That said, the beliefs you hold and the mindsets you adopt influence how the body adapts to those circumstances. When it comes to your health and fitness, it's not just what you choose to do, it's also what you choose to think about what you do.

You're no doubt familiar with the placebo effect. How does it apply to exercise? Let's find out.

Hey there. It’s me, Kore. And you're listening to Exercising Self-Control: From Fitness To Flourishing.

Ellen Langer, an American professor of psychology at Harvard University, once suggested “the benefit of exercise is just a placebo.” The placebo effect refers to taking an inactive substance, commonly called a sugar pill, assuming it's real, that it's medicine, and getting the results you'd expect to get from real medicine. In other words, you believe you're going to get better, and you do, just because that's what you expected. The effect has a lot of data to back it up, because every new drug must outperform the placebo effect to be approved.

Professor Langer made her claim about exercise and the placebo effect to Dr. Alia Crum, a student at the time who she was mentoring. Professor Langer was being provocative, but also wanted to explore this idea. This led to a study they published together, entitled Mindset Matters: Exercise and the Placebo Effect.

They got together 84 female hotel room attendants for the study. They measured health variables affected by exercise: weight, body fat, blood pressure, waist to hip ratio, and body mass index. They divided the group into informed and uninformed. Those in the informed group were told that cleaning hotel rooms is good exercise, and all that activity satisfies the general recommendations for an active lifestyle. They were provided examples of how the movements they regularly performed in their duties mimicked exercise movements they might do in a gym. Those in the uninformed control group were not given this information.

Four weeks later, the informed group let the researchers know they were getting more exercise than they initially reported. That makes sense, as they were essentially told this is what was happening, although their actual behaviour did not change. The participants were carefully monitored to ensure that they did not do any extra exercise or that they changed their diet.

And what about the changes other than their perceived levels of exercise? Compared to the control group, they improved all their measurements. Weight, blood pressure, body fat, waist to hip ratio, and body mass index all improved.

That's pretty amazing because here's all that changed. Initially, the hotel workers thought, “Work is work, but it's not exercise.” Then they were informed, “Actually, work is exercise.” That's all it took for their bodies to adapt to their work differently by making them healthier. A belief changed their results without changing anything else.

There were criticisms of the study. For example, maybe they changed their behaviour without realizing it. They might have moved faster or carried more supplies during their work day, for example. That's certainly a possibility, though the amount of work didn't substantially change as per the hotels’ regular booking schedules.

So can mindset actually change the objective physiology of the body other than maybe just getting someone to change their behaviour without conscious awareness, as was suggested in the criticism?

Another study, done with milkshakes this time, provides some pretty wild evidence that it can. This study, entitled Mind over Milkshakes: Mindsets, Not Just Nutrients, Determine Ghrelin Response, was also done by Dr. Alia Crum.

A supply of French vanilla milkshake was concocted and divided into two batches. One was the sensible shake. This was labeled as having zero percent fat, zero added sugar, and only 140 calories. The second was called the indulgent shake. This was labeled as containing vanilla ice cream, whole milk, and a whopping 620 calories. In fact, both were the same and had 380 calories per serving.

When participants in the study believed they consumed the indulgent high-calorie milkshake, their ghrelin levels dropped three times more rapidly. This implied their bodies responded as if they had consumed more food, feeling fuller and more satisfied.

Ghrelin is the hunger hormone. When ghrelin rises high enough in the stomach, that's the signal, “time to eat.” Initially, the scientific understanding was that ghrelin levels were dictated b