Weight-loss drug found to shrink muscle in mice, human cells

That's the sort of headlines that smells like bullshit to me.

My understand of those drugs is that they don't actually make you lose weight, they just cut your appetite so you can follow a diet to lose weight without hunger hammering at the door. So to start with, if that's the case, all they are observing is the effect of a diet. Not sure the diet drug has much to do with it.

Then I went from 133kg to 88kg with these diet drugs. Even though I exercised every day, I am sure I also lost some muscle mass as well, just because I don't have to carry 45kg every time I make a move anymore. Seems logical and would probably be concerned if it was any other way.

> Carla Prado, a nutrition researcher in the Faculty of Agricultural, Life & Environmental Sciences and lead author on the commentary, explains this rate of muscle decline is significantly higher than what is typically observed with calorie-reduced diets or normal aging and could lead to a host of long-term health issues — including decreased immunity, increased risk of infections and poor wound healing.

The rather obvious problem is that these GLP1 agonists don't improve your diet. If you continue to eat a protein and nutrient deficient diet (which is probably a majority of Americans) with caloric restriction on top of that, that leads to excessive muscle loss that you wouldn't see in a weight loss diet. This normally doesn't happen without GLP1 agonists, because these diets are too difficult to stick to for most people. Those who stick to them usually turn to nutritious high satiety whole foods that help combat the negative effects of caloric restriction.

Losing weight without losing muscle mass is very hard. It requires extreme diets like a protein sparring modified fast where 80%+ of your calories are from lean protein while running a 50% caloric deficit. If this research is correct, then using GLP1 agonists shortcuts the feedback loops that make the diets hard to stick to, but they shift the tradeoffs from weight to overall nutrition.

"When a measure becomes a target, it ceases to be a good measure" and all that.

I was with you up to here. In my experience it's easy to maintain a huge proportion of your lean tissue during a weight loss diet: Do some resistance training, get some protein, and don't lose weight too quickly.

There's no need to go to the extreme of a PSMF - which will still have you lose a bunch of muscle on account of being too big a deficit. If you can keep your calories reasonable while on a GLP1 agonist, there doesn't seem to be any reason you'll lose an exaggerated amount of muscle.

Is it possible to go very slow and keep most of your lean muscle mass? Sure. Is it practical? I have my doubts.

Part of the effectiveness of these drugs - for me at least - is that results are rapid and that is a self-reinforcing feedback loop. Diets that had me losing 1lb/week were simply too boring and unmotivating for me to keep up beyond a few months. A few days of vacation “cheating” and you wipe out a month or more of incredibly difficult to achieve loss. Restricting yourself mentally in what you eat every day adds up to exhaustion over time.

Some folks can manage to lose very slowly while also adhering to a strict calorie deficit of a few hundred per day, while also being consistent with resistance training. I’d say the evidence shows that these folks are in the small minority.

I will say more evidence is needed for this drug class - especially where the harm reduction principle may be a bit iffy outside of obese folks. However it was life changing to me in the way it let me change my eating habits to very healthy protein and veggies as my primary calorie intake, as well as made going to the gym on a strict schedule motivating enough to actually come out at the end with a better bodyfat to lean muscle ratio than where I started.

These gains have continued since I hit my goal weight - and now I’m starting to become one of those folks who the BMI no longer applies to in a good way. I do wish there was a good way to test heart muscle mass like there is lean body mass with a DEXA scan as I’m curious if my increased regular workout heartrates translates into building back any heart muscle mass like it did other lean muscle. Certainly a concern to keep an eye out for!

I’m curious as you are if folks who are slow responders and live active lifestyles see the same muscle loss the hyper responders do. For reference I lost over 100lbs in just under 9mo. I absolutely lost considerable muscle mass, but have since put it back on and then some.