This is both scientifically untrue and longitudinally true.

Of course if you use exercise to help create a calorie deficit you will lose weight. However, every single study shows that most people won’t lose weight by exercising. They overestimate how much they burn and underestimate how much they lose eat. Exercise also tends to make you hungrier and it makes it harder to not eat more. Also, hardly anyone has the discipline to work out consistently over a long period of time or the fitness level to work out long enough and have enough to use exercise as a weight loss tool.

You appear to be agreeing with me?

I’m saying it’s more nuanced. Anecdotally, I spent a decade keeping weight off by exercising 10+ hours a week as a part time fitness instructor and training for runs. Even now I lose weight by exercising. But most people aren’t going to work out at the consistency and intensity that I do. It takes more discipline for me not to workout too much.

Gaining weight even when calorie controlled due to exercise is possible, but you will lose fat percentage while gaining muscle mass thus increasing base metabolic rate. Doubly good.

Which is why you should get one of the approximate fat percentage meters. (Clamp better than electric but less convenient.) And maybe run a DEXA or volumetric body composition scan sometimes.

Another good easy measure is the belt size, for obese people. Smaller is better. Or waist/hip ratio. Requires a tape measure, that's it.

If you exercise and weight stays the same but belt size goes down, you're on the right track.

Exercise can absolutely contribute to weight loss. It does not guarantee weight loss because an individual can always eat more than they burn (and indeed many do). That doesn’t mean it’s not a very useful tool for weight loss in a continued caloric deficit.

Maintain your caloric intake level “at maintenance” and add 5 miles of running per day and you’ll lose weight.

> Exercise can absolutely contribute to weight loss

That's not what the evidence says.

You’re clearly speaking in generalities because the evidence is absolutely there that people can lose weight by exercising. But if you’re speaking in generalities then people basically don’t lose weight at all. The studies indicate that nearly no one keeps weight off long term.

If you restrict your sample to the select few that do keep off the weight, some do it with diet alone. Some do it with diet and exercise. Some very few do it with exercise alone. Any of these strategies can work. But in general, none of them do.

That’s not what studies show. Studies show that most people can not lose weight by exercise alone:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3925973/

Scientifically it is possible, but that’s not backed up by how humans actually behave.

Sorry, is there something specific in that article that supports your claim, because I’m skimming over it and seeing lots of stuff that supports the assertion that people do indeed lose weight from exercise, that it generally requires a relatively high amount of exercise, but that it varies a lot between individuals.

> Overall, the changes in weight in response to ET without caloric restriction are highly heterogeneous and individual differences can span weight gain to clinically significant weight loss.

> Supervised ET studies which have demonstrated clinically significant weight loss with aerobic ET (without caloric restriction) have far exceeded the minimum levels of physical activity according to public health definitions. Ross et al. observed an 8% weight loss in obese men after 12 weeks of aerobic ET with no alterations in dietary habits(daily exercise sessions of 700 kcals). In a different study, Ross et al. observed an 6.8% weight loss in premenopausal women (BMI>27) following 14 weeks of aerobic ET with an energy expenditure of 500 kcals per session. In the Midwest Exercise Trial, Donnelly et al. (n=131) observed a 5.3% weight loss in men after 16 weeks of aerobic ET at approximately 2,000 kcals per week. In contrast, the women in the exercise group did not have a significant change in weight (0.7 kg) following the intervention, but the exercise program prevented the weight gain observed in the control group (2.9 kg.) Thus, clinically significant weight loss is possible with aerobic ET without caloric restriction, but it requires a high ET volume. For the general population, these ET volumes may not be practical or sustainable.

In general, weight loss intervention doesn’t work well. Most people fail to lose significant weight, to adhere for an extended time, or to keep the weight off for years. This is the case no matter how the weight loss is achieved. Even gastric bypass patients often manage to gain back enough weight to get back to the obese mark. That doesn’t mean weight loss is impossible, but it is definitely hard. Exercise is absolutely a way to lose weight, but you have to be serious about it and do considerably more than the minimum recommendation, or you have to restrict calories, or preferably both. And you have to somehow maintain long term if you don’t want to immediately gain it back.

The evidence doesn’t say it’s not possible. If we were all homo logicus exercised consistently and kept our caloric intake in equilibrium to our BMR and added exercise on top of it, it can be done. But it doesn’t work in practice for most people.