I’ve noticed recently that compared to my calculated energy deficit, there has been considerably more weight change than I expected.
For context, there are 1 or 2 hill climb segments I do each year and I try to lean out a bit before each event.
If muscle is 75-79% water, the rest is mostly protein (4kcal/g). I’ve calculated 880 kcal/kg of muscle mass, which explains what I’m observing much better than the 7700 kcal/kg of fat mass.
I’m aware that this does carry some health risks, but is the math mathing? Thanks!
I’m not exactly sure what you’re calculating here but realize if you have a power meter then calorie expenditure is directly related to Watts. It has nothing to do with your fat mass or anything else. Calories are just a measurement of energy and Watts are just a measurement of energy so it’s a simple conversion.
But also realize that food calories are very inaccurate and the amount you burn in general is inaccurate. So if you’re losing weight faster than expected, it’s more likely that you just have a larger deficit. We also don’t really know accurately what our metabolic rate is. That said people still get good systems of figuring out what they can eat versus what they burn to lose weight but the mouth is just a rough estimate to get you in the ballpark.
I’m referring to the general statement that an energy deficit of 3500 calories is roughly a pound (7700/kg). The energy expenditure figures are measured with a power meter so I believe they’re reasonably close.
I have a calculated deficit of about 800 calories/wk but have lost closer to a kg. This started happening recently, (and every time I approach a certain bf%). I’ve been eating the same foods for over 5 years now, so the error in the system is unlikely to be of of that magnitude. 6900 kcal/week is ~1000 kcal a day and given my sedentary TDEE baseline of 1570 kcal, it’s impossible that I’m only actually eating 570 cal a day and not know it.
Cachexia for example is a condition where most of the mass lost is lean mass and the weight loss is greatly in excess of what typical calculations show. I suspect this is common for athletes that are close to minimal bf% and the body begins to preferentially conserve fat in favour of metabolizing lean mass. I find it incredibly difficult to be able to hit nutrition targets, particularly when even small deficits create large changes in weight.
TLDR: Is it true that 1 kg of lean mass can be catabolized for approximately 880 kcal?
I think calorie restriction calculations are a “get me close” for weight loss.
You only find out if you’re actually in a deficit if you lose weight above and beyond normal daily variation and water losses.
I think in your case either due to food calorie inaccuracy, your metabolic rate, etc… you are in a bigger deficit than you thought and you lost more weight than would be expected.
My TDEE is indeed 1570 calories if I sit at home and am completely sedentary. During periods when I am not training/cycling I will maintain my weight eating that many calories. Sailrabbit’s calculator shows that I’m in the right range generally.
I eat the exact same food items weighed out for accuracy for almost a decade now, so it’s unlikely to be the source of error. Rather it may not be accurate but it is precise.
I suppose it’s not a phenomenon many will have experience with, as knocking on the floor of minimal bf% has some pretty nasty health effects.
PS: That 6900 kcal is a estimate of what the deficit would need to be had all the mass been lost was fat.
Thanks!