Adjusting beliefs to keep up with the latest science


We’ve all been there. You open the paper — or more likely, your computer or Twitter on your phone — and you see a headline that directly contradicts something you strongly believe to be true.

What do you do?

Do you immediately cast away your firmly held belief based on one headline or one scientific study?

Or, do you immediately discount the headline and the study because it “can’t be true” given all you believe?

Or, as a third option, do you open the door to reassessing your belief and evaluating the science on its own merits?

It should be clear that the third option is the “best,” but it can also be a surprisingly tricky thing to do.

A great example is using hormone replacement therapy (HRT) to treat postmenopausal women for bone health and cardiovascular prevention. Observational studies and clear medical consensus said we should give women HRT. I did it as a resident; my attendings did it for their patients. And we never saw any complications from it. We felt good about ourselves for helping people, and we firmly believed it was the right thing to do.

A few years later, a large randomized controlled trial showed that giving HRT to postmenopausal women worsened heart disease risk. How could this be? How could we have been wrong for so long? It was a complete shock and forced me and just about every other doctor to reevaluate what we believed.

We quickly came to the realization we were “wrong” and started warning women about HRT. It was dangerous. Regardless of bone health benefits, you shouldn’t do it.

Then came the nuanced discussions. “Hold on a minute,” some said. This trial involved a specific type of oral HRT. Other methods of delivery could have completely different physiologic effects. This trial showed harm in women who were treated “late” after menopause, not in those treated early. Other specific corrections followed.

The discussion then turned from “Don’t give HRT since it is uniformly dangerous…” to a discussion about “One trial can’t evaluate every aspect of care, so we need to apply the findings more selectively.”

Yes, it’s true. Randomized controlled trials are a higher quality of evidence than observational studies. But that doesn’t make them perfect.

Scientists design trials to test a specific hypothesis in a particular group of people over a pre-specified time period. Randomized controlled trials can answer questions very well under those constraints.

But can one trial reverse the scientific beliefs about an entire field? Did one randomized controlled trial completely change the use of HRT? At first, it seemed like it did. But now, for most physicians, it forces us to think harder about the right settings and the right formulations. It isn’t a blanket, “yes or no,” “good or bad.” It forces us to embrace the details and apply them to help our patients as individuals.

That’s how I think about the study on time-restricted eating just published in JAMA Internal Medicine. I already covered it in a previous post, and I have gotten some pushback about it. Many of the comments were encouraging, but some, rightly so, questioned my defensiveness.

And this got me thinking. What is the proper balance of questioning, calling out the specifics and nuance, versus completely shutting my eyes to the possibility I could be wrong?

I like to think that I’m not blinded by my beliefs and that can’t I accept that some of my current ideas are wrong. That’s science — figuring out which hypotheses are, in fact, false. My theories about time-restricted eating come from published studies, some randomized controlled trials, but many non-randomized trials, as well as my own personal and professional experience.

The new study is an essential contribution to science. It is one study, with one trial design, testing one specific situation. The results deserve to be noted and taken seriously.

But they also deserve to be questioned, teased out, and dissected to understand how they can change or cement what we believe. That’s how science works.

My conclusions?

  1. The food we eat matters.
  2. Getting adequate protein matters.
  3. The timing of when we eat still matters.
  4. Physical activity, sleep, and healthy lifestyles still matter.

But it isn’t as simple as “eat whatever you want as long as it’s in an eight-hour window.” While I didn’t think this type of fasting was the best approach, and it wasn’t what I ever recommended, I did believe that it could be true. Thanks to this study, I no longer believe that to be completely true.

We all can benefit by realizing time-restricted eating isn’t one thing. And it isn’t a cure-all. But let’s not throw it out entirely. Instead, let’s dissect what we know, what we don’t know, and consider the best approach for each individual, given their unique situation.

Thanks for reading,
Bret Scher, MD FACC

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