“You can’t lose weight without changing your diet.”

Oh, really? Somebody should probably tell the researchers. And the people who lost weight without changing their diets. This is going to be an awkward meeting.

I hear this constantly in the fitness industry. Someone says it confidently enough, puts it over a video of themselves pointing at floating words, and suddenly we are all supposed to accept it as fact.

Listen. Nutrition matters. Of course it matters. I own fitness facilities. I coach people. I have also stood in front of an open refrigerator negotiating with myself like there was a hostage situation inside. I understand the importance of food.

But saying dietary changes can help someone lose weight is very different from saying someone CANNOT lose weight without them.

That second claim has a research problem.

The American College of Sports Medicine’s 2022 consensus statement on exercise and type 2 diabetes discusses weight loss from physical activity alone. The authors explain that average losses are generally modest, but substantial amounts of exercise can produce larger losses. They cite trials in which approximately an hour of daily aerobic exercise produced weight loss comparable to dietary restriction (Kanaley et al., 2022).

Yes. Exercise. Without a prescribed calorie restricted diet.

And before someone says, “Well, those people had diabetes,” let’s actually look at one of the studies.

Ross and colleagues studied 54 premenopausal women with abdominal obesity. The women were screened for normal glucose tolerance. Participants were assigned to dietary weight loss, exercise weight loss, exercise without weight loss, or a control group for 14 weeks (Ross et al., 2004).

Both weight loss groups lost approximately 6.5 percent of their body weight. The exercise weight loss group had greater reductions in total and abdominal fat than the other groups. Visceral fat decreased in all three intervention groups, including the women who exercised without losing weight (Ross et al., 2004).

Now, here is the part that makes the absolute “you MUST change your diet” argument uncomfortable: reported calorie intake did not decrease in the exercise weight loss group. They averaged approximately 64 minutes of exercise and 524 calories expended per session, with 96 percent attendance (Ross et al., 2004).

So they exercised consistently, did not report eating fewer calories, and lost weight.

We can retire “impossible” now. It has had a good run.

There is also a basic distinction getting lost in this conversation. A calorie deficit does not automatically mean a calorie restricted diet. A deficit describes the relationship between what you take in and what you expend. Reducing intake is one way to create it. Increasing expenditure is another.

Your body does not require you to download a meal tracking app before it recognizes that relationship.

Does that mean an occasional walk will erase every eating decision you make? No. The women in this study completed a substantial exercise program with very high attendance. Approximately an hour per session. Consistently. Those details matter, and I am not going to conveniently leave them out because I like the conclusion.

But they also do not make the result disappear.

This is where the fitness industry drives me slightly more insane than I already am. We take a reasonable statement like “dietary changes often make weight loss easier” and somehow turn it into “exercise cannot produce weight loss.”

HOW DID WE GET THERE?

Those are different claims. You cannot swap them around because the second one sounds better in a thirty second video.

And honestly, the scale may not even be the most interesting part of this research. The exercise group that maintained its weight still reduced total and abdominal fat (Ross et al., 2004).

Imagine doing the work, improving your body composition, and then being told it “isn’t working” because your bathroom scale has refused to clap for you.

That is a problem with how we assess progress.

The ACSM statement also describes improvements in fitness and metabolic health without weight loss in people with type 2 diabetes. Exercise is accomplishing things that pounds alone cannot tell us about (Kanaley et al., 2022).

As a coach, I want to know whether someone is getting fitter, functioning better, and making measurable progress. I care about body weight when it is relevant. I just refuse to hand the entire evaluation over to a rectangle on the bathroom floor.

My opinion? Help people with nutrition. Absolutely. If adjusting food intake makes their goal more achievable, use that tool. But stop telling them exercise cannot produce weight loss without it. The evidence does not support that statement.

Exercise alone often produces modest average weight loss. Higher amounts, completed consistently, can produce meaningful losses. It can also improve fat distribution even when weight stays stable. All of those things can be true at the same time.

We are supposed to be educators. That means giving people an accurate explanation, even when it takes a few more words than a catchy slogan.

And if the research disagrees with something we have been yelling for years, we can change what we are yelling.

Trust me. I am exceptionally qualified to speak on the yelling part.

References

Kanaley, J. A., Colberg, S. R., Corcoran, M. H., Malin, S. K., Rodriguez, N. R., Crespo, C. J., Kirwan, J. P., & Zierath, J. R. (2022). Exercise/physical activity in individuals with type 2 diabetes: A consensus statement from the American College of Sports Medicine. Medicine & Science in Sports & Exercise, 54(2), 353–368. https://doi.org/10.1249/MSS.0000000000002800

Ross, R., Janssen, I., Dawson, J., Kungl, A. M., Kuk, J. L., Wong, S. L., Nguyen-Duy, T. B., Lee, S., Kilpatrick, K., & Hudson, R. (2004). Exercise-induced reduction in obesity and insulin resistance in women: A randomized controlled trial. Obesity Research, 12(5), 789–798. https://doi.org/10.1038/oby.2004.95