I disagree completely. Regular caloric restriction has its place, exercise has its place, and intermittent fasting has its place.

My wife and I are long distance hikers. That means carrying 10-15kg up and down mountains for 10-14 hours per day every day for 3-6 months.

It also means literally counting every calorie--because you have to plan it in week-long intervals and also optimize it for minimal weight and sufficient nutrients.

Sounds like a perfect recipe for weight loss right? Enter 'hiker hunger.'

Appetite is completely elastic. Your ability to perform depends on your brain's ability to produce happy endorphins and satisfaction signals etc.

That's where intermittent fasting is crucial. You exercise your body's regulatory functions. It's not just some belief or willpower or placebo I mean: at a chemical level you transform the function of your neurochemistry to improve your metabolic process.

> That's where intermittent fasting is crucial

Would you be able to use IF during a thru hike? I suspect that the answer is no. The weight gain problem for distance hikers is after the hike is finished and we reduce activity significantly. I've solved that by training for distance races when I'm not hiking.

Zach Bitter, the current 100 mile record holder, put it in a way that makes a lot of sense to me[0]. For a mere mortal, fasting for 6 hours puts you in the hole for about 700 kcal. A world class athlete like him is at more like a 2000+ kcal deficit. It's impossible to catch up once you get that far behind, and you end up losing weight and injuring yourself. I only burn about 800 kcal during training on an easy day, but I still find it nearly impossible to catch up if I miss a meal. I'm already eating 5x a day. It's hard to cram 5 full meals into a few hours.

[0]: https://zachbitter.com/blog/2014/04/06/intermittent_fasting_...

Of course not.

And weight gain is not contained to "after the trail"

And weight loss is not guaranteed.

It's great that you've found something that works for you. Like I said, it works for me too.

Bodies are different though.

"I've hacked around this problem" != "This problem is illusory"

Being active is one factor, but doesn't fix obesity. It's also difficult or even potentially harmful to start doing some kinds of activity when you're extremely obese.

Highly active is something you can be when you're at or approaching a healthy weight; the causality is IMO almost backwards from what you've described.

You can't outrun a bad diet. It's way too easy to overeat in our modern world, even if you're active.

> You can't outrun a bad diet

In spite of jamming as much junk food down my throat as I possibly could, I struggled to maintain weight on the Appalachian trail. You can definitely outrun a bad diet. (Not that it's a healthy way to live either.)

Not everyone can. Genetic factors and how your body handles insulin determine almost everything about how your body will gain or lose weight and in what conditions.

Gary Taubes book “Why we get fat,” is a great read on this subject.

I agree that outrunning a diet is something that outliers do, but has Gary Taubes found a way for his foundation to confirm his claims after it refuted them? There's little doubt that genetics and how your body handles insulin have influence, but the variations still don't compare with how many calories you consume versus how much you move, given a healthy diet.

You can eat a lot of calories and lose weight.

I have lost weight like that before, but can't maintain a 2 hour a day exercise routine.

I imagine you can't stay on the Appalachian trail forever.

So eventually a bad diet will lap us.

I had the same problem on the AT.

But, yknow, HYOH

My mom used to regularly fast for "religious" purposes. One day during a week long fast she passed out in the shower. According to the doctor it's because we're not supposed to keep a full schedule while fasting.

Was it a wet fast or a dry fast?

> According to the doctor it's because we're not supposed to keep a full schedule while fasting.

That's a standard answer that likely does not draw on his medical knowledge. People pass out even when not fasting (women more so than man, something to do with vagus nerve IIRC), and thousands of people do long wet fasts while keeping a full schedule with no ill effects.