A large volume of studies already exist.

That intense exercise is good, and even very good for you, is proven as far as reasonably possible given that we can't run deterministically controlled experiments.

More evidence may come out that adds nuance, but the effect size is so large that it becomes obvious in the data just from observation.

You can cycle or stationary bike if you have bad knees. There are plenty of exercises that are intense but easy on the joints.

> You'd need to find subjects that are provably capable of sustaining intense exercise as a habit if they wanted to but never did, and won't either for the years you'll be following them.

With modern 24/7 health tracking we’ll have tons of data in the next 50-100 years. Problem is we need that much time to see the net effect and will probably be too late for most of you reading this.

I wouldn’t wait for the results though. Best to start moving now assuming it’s probably good for you.

I challenge you to look for studies. Read a few. There are hundreds on this topic!

The claim comes from this study:

https://www.acpjournals.org/doi/pdf/10.7326/M15-1181

Though to be clear, there aren't a ton of studies that look at bodyfat percentage. Most use BMI and similar measures.

Likely overall fat levels matter more than %, I'd guess.

E.g. I'd presume being 15% at very muscular levels is less healthy than 15% at moderate.

(Because absolute fat mass plus visceral fat would be higher)

Sounds like absolute BS to me. Even in very large scale studies specifically designed for studying mortality, only morbid obesity has been negatively correlated with lifespan. There is even some evidence that being a little overweight is actually helpful for the very old (essentially, because it gives them more buffer if they get sick enough that they stop eating for a while). A lot of this is because modern medicine has gotten very good at treating stuff like diabetes and other stuff caused by obesity. Your quality of life will undoubtedly improve if you are thinner, but that's not the same thing.

I just named my dracula training program.

First, learn to sleep on your back

Second, attach the blanket to the bottom of the bed and learn to sleep with your knees up. Use the blanket to help.

Third, put some books under the legs (on the head end)

Keep adding books until you almost slide down, get used to it and add more books.

Eventually you wake up feeling like you did a proper leg day.

Keep at it and go for isometric nucleus overload. Every 6 weeks remove half the books for 2 weeks.

You will grow enormous legs and they will stay that way.

I suppose you could tie rubber bands to your arms in stead of the books but I haven't tried that. I'm sure it will make for a memorable period of your life. ha-ha

Carbon dioxide is produced as a metabolic waste product from exercise. Any sort of fat-burning you want to do is limited by the rate at which you can exhale CO2. This is why vigorous exercise is accompanied by heavy breathing. This includes not only cardiovascular training but also weight training. Lifting heavy weights will have you breathing very hard!

Unfortunately, if you don’t lift heavy (or if you use electrical stimulation that’s mild enough to sleep) then you’re not going to put your muscles into hypertrophy, so you won’t gain muscle mass either.

It can't, because it isn't training your heart and cardiovascular system.