It seems the article isn't just saying it's heart muscle that's being lost but regular muscle in general. Even more so than in a low calorie diet.
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There are very complex dietary regimes that can be followed to minimize this, but most studies have shown that they don't save any time compared to losing weight and then working to get the muscle back afterwards.
> Dyck’s study comes on the heels of a commentary published in the November issue of The Lancet by an international team of researchers from the U of A, McMaster and Louisiana State University who examined emerging research showing that up to 40 per cent of the weight lost by people using weight-loss drugs is actually muscle.
This is, again 100% typical of what happens with caloric restriction.
>Studies suggest muscle loss with these medications (as indicated by decreases in fat-free mass [FFM]) ranges from 25% to 39% of the total weight lost over 36–72 weeks. This substantial muscle loss can be largely attributed to the magnitude of weight loss, rather than by an independent effect of GLP-1 receptor agonists, although this hypothesis must be tested. By comparison, non-pharmacological caloric restriction studies with smaller magnitudes of weight loss result in 10–30% FFM losses.
Comparing weight loss of different magnitudes is kind of comparing apples to oranges. Of course, it's not really possible to get persistent, large magnitude weight loss any other way than by using these drugs, so I understand why the comparison was made.
> 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.
Do you have a source that 40% muscle loss is typical for a caloric restriction diet without GLP1 agonists?
I started losing weight from severe obesity with a caloric deficit but noticed I was also feeling weaker in general (aside from the tiredness that comes with eating under your TDEE).
I started going to a trainer and he had me change my macros so that I was consuming about 200g of protein per day in addition to 4 days per week of full body workouts on top of my cardio.
Since then I’ve lost an additional 150% of my initial weight loss, and have gained moderate muscle mass on top of that.
OK I actually checked up on this, and it is more like 30%, but that number gets worse as you get older. For young healthy men it can be 20%, but as you get older that number gets worse and worse.
I'd want to see a comparison of a similar cohort of people going on a calorie restricted diet of the same magnitude, with a similar (lack of) activity levels.
The study at https://www.thelancet.com/journals/landia/article/PIIS2213-8... compares people who had less overall weight loss on a pure calorie restricting diet, which, well, by definition isn't the same thing.
Professional body builders do bulk/cut/bulk/cut because after awhile you can't lose weight and put on muscle at the same time, especially if you want to get to the point of being shredded.
(well you can do it, but there is no benefit over bulking and cutting)