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You may have seen news stories this week saying that if you exercise in the morning, you’ll lose more weight. Can this be true?

Related HCT episodes:
1. Exercise is Really Good For You:
2. Exercise is NOT the Key to Weight Loss:

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You may have seen news stories this week saying that if you exercise in the morning, you'll lose more weight. Place your bets now to see if I agree. This is Healthcare Triage News.


If you bet that I'd agree, you need to watch more Healthcare Triage. To the research!

Recent publication in the International Journal of Obesity, The effects of exercise session timing on weight loss and components of energy balance: midwest exercise trial 2.

The researchers gathered together something less than 100 overweight or obese, physically inactive young adults and put them in a 10-month supervised exercise program for five days a week. This was a RCT originally, so there were controls who were not assigned to exercise. And, obviously, the participants weren't blinded, they new if they were exercising or not.

Those in the intervention group could exercise any time they wanted from 7 A.M. to 7 P.M. on weekdays and shortened hours on Saturday, when the university exercise facility was open.

And, like you'd expect if you've watched out episodes on exercise and weight loss, they loss less weight than you'd expect given the calorie burn. They also lost wildly different amounts of weight. That's because what you eat tends to matter much more than exercise when it comes to weight loss. 

That was a previous study, of course. This study was a sub-analysis of the original study. It's not a randomized controlled trial. People were not randomized to time-of-day exercise. Don't be fooled by reports that got this wrong.

In this study, the grouped people by when they tended to exercise. Early people did so before noon. Early afternoon went from noon to 3 P.M. Late afternoon went from 3 to 7 P.M. "Sporadic" people were those where no one time period was used more than half  the time.

There were 21 early people, 11 mid-day people, 25 late people, and 24 sporadic people. So, don't go think this trial was huge, either. Oh, and the mid-day group was so small, it had to be dropped from the analysis.

They found that after 10 months, more people in the early group lost a meaningful amount of weight (81%), followed by the sporadic group (54%), and followed by the late group (36%).

Before you all go changing your routines, remember that this is not a randomized controlled trial. It's totally possible that there are other differences in people who choose to exercise at different times of the day that matter. In fact, this study found a few differences, itself.

People in the early exercise group ate more (more than 200 calories each day) than late exercisers did at 10 months. Why? We don't know. People who exercised later in the day tended to be less active overall than those who exercised early in the morning. Why? We don't know. I can guess. Maybe those who exercise earlier had different types of jobs. Maybe they belong to different socio-economic classes, or something else that might make a difference. But, if I'm being honest, I'm not sure I care to delve into that too much. The differences from person to person are huge.

Each line in this figure is a different person. As you can see, most people lost weight. And, if you randomly picked a person in any group, you'd still see big differences. And still, we're talking about like 20 people in each group. These are not concrete, randomized controlled trial data that should convince you to change your mind on anything. 

Now, Erik Willis, one of the researchers, did hedge in a story I saw him quoted in, and I'm quoting him now: "Based on this data, I would say that the timing of exercise might—just might—play a roll" in whether and to what extent people drop pounds with exercise.

I can't stress the might enough. We could do a randomized controlled trial of this. We could see whether the time of exercise works. But, I'm not going to hold my breath, because, again, who cares. The purpose of exercise is not to lose weight. It's to get all of the amazing health benefits that come with it, no matter what time you exercise.


Hey, if you like this video, you might like this other video on why exercise is pretty much a wonder drug.

And, if you love this video, you can support it at, where you, like our research associate, Joe Sevits, and our surgeon admiral, Sam, can support the show in any way you'd like.