Test that shows you have a “slow metabolism”

I think “slow” is subjective. It’s rare to have a truly slow or fast metabolism without hormone issues, and those are serious and need treatment. Everyone’s metabolism is on a scale and I would be really surprised if there was much difference between slow and normal in percentage points - unless indicated by hormones.

To give context, I had a “fast” metabolism for c26 years. It was absolute hell and I felt dreadful a lot of the time with deeply unpleasant side effects. Yet it was only just classed as fast - because of the scale I mentioned. I still managed to put weight on even with a faster metabolism. It just meant I felt ill. Pretty much all the time.

Things like EPOC and the process of adding lean mass (hypertrophy) affect metabolism in the calorie-needs sense, too. I suspect healing other injuries does. I think unusual consumption of calories above maintenance technically does, too, since things like core temperature upregulate.

Some of those would be transitory effects, and generally not huge.

Personally, I don't see the point of worrying about it as an individual. My metabolic rate is what it is. Some things I do might increase it, but I do them for other reasons, not with metabolic increase as the main point. (Examples: Strength training, over-eating 😉.) Given the small effect size, doing them just to burn extra calories seems like the same kind of silly majoring in the minors like eating hot peppers or other foods that increase calorie expenditure by some trivial amount.

Oh the flip side, if my metabolism is slow, what would I personally do or suggest? Run the 4-6 weeks/one menstrual cycle calorie experiment, and personalize goal based on real world results. Increasing NEAT or exercise will have a bigger calorie impact than trying to jack around with "metabolic hacks".

Mostly - and I say this as someone hypothyroid, old, menopausal myself - saying "it's so hard because I have a slow metabolism" is just another "it's so hard because . . . ".

Not meaning to be harsh, but everyone's got some kind of hard. I feel like the only point of thinking about roadblocks is figuring out how to get over, around, through or otherwise past them. Anything else is unproductive . . . and maybe just whining.

Not sure if this is what you mean, but

Years ago, I had a major life trauma, gained 60 pounds in 3 months, went to a well-respected bariatric Dr. (No surgery). He had me strip to underwear, lay quietly in a clear coffin-like box that was supposed to measure calories burned. After, he told me I burned about 800 calories a day, and unfortunately, there was nothing he could do to help me—don't come back.

After a while, I got over the trauma and my bmr and tdee are pretty close to average/expected.

Yeah, that sounds like one of the indirect calorimetry tests.

And yes, I'm sure some health-improving interventions improve metabolic rate. Some also increase NEAT in not- necessarily-obvious ways, too. (Example: Betcha people getting good sleep are less fatigued, so probably move more and rest less in daily life but don't necessarily notice that activity increase.)

There some health-promoting interventions that tend to reduce metabolic rate, too, though, right? Like losing a large amount of weight? 😉

Though I admit to being "normal" (as it turns out) when I started losing weight and very much scaling in line with population parameters, it doesn't mean that the expectation of finding a significant number of people who run "slow" is not there.

Using the examine.com numbers (article is available on free play): "Extending this into practical terms and assuming an average expenditure of 2000kcal a day, 68% of the population falls into the range of 1840-2160kcal daily while 96% of the population is in the range of 1680-2320kcal daily. Comparing somebody at or below the 5th  percentile with somebody at or above the 95 th  percentile would yield a difference of possibly 600kcal daily, and the chance of this occurring (comparing the self to a friend) is 0.50%, assuming two completely random persons."

Let's just look at the 2000 to 1680. That's 320 Cal. This means that the 1680 person would probably "not lose any weight" when trying to implement -500 Cal a day (logging errors and inability to see progress at a small deficit would ensure of that)

But that's only 2% of the population… nothing, right?

That's 800,000 people in Canada
That's 1,400,000 people in the UK
That's 7,000,000 people in the USA.
That's 164,000,000 people in the WORLD.

How many users does MFP have?
Supposedly, 2.5% of the world's population are users ;-)
(I sincerely doubt that even a quarter are both unique and active users)

Sure, Ann is part of the "other side" of the 2%. I'm part of the 68% metabolically, albeit with a much much higher tdee.

But how do we know ahead of time that MFP users are actually a representative sample?
How do we know that MFP users are not self selected, overwhelmingly, from the low 2%?

In which case "slow metabolism" could be 20% instead of 2% of the MFP population… (or any other %, currently unknown)

Sure, but I can also bemoan the reality that someone who weighs 200 pounds will burn 2 to 3 times more calories than me just walking. The reality is we're all different, with different bodies, so really, bemoaning a slow metabolism is unhelpful at best. There are other factors that affect our caloric intake much more.

And getting old.

At 50, 250 pounds, I steadily lost 10 pounds/month on 1600 calories

At 75, 180 pounds, retired, inactive, tdee is close to 1600

Both pretty close to predicted/average.

Yes, for clarity, I think we need to say whether we mean RMR/BMR when we're talking about slow metabolism, or instead including NEAT.

The Examine.com article and the research review paper I linked are - in the mentions of 5-8% being one standard deviation - are talking about RMR, not including NEAT.

In fact, the abstract of the research review says "Total daily energy expenditure varies several-fold in humans, not due to variation in res ting metabolic rate, diet-induced thermogenesis, or exercise thermogenesis, but rather, due to variations in nonexercise activity."

In other words, NEAT is the biggie explaining caloire-needs differences among people. On a statistical level, intentional exercise is a substantially smaller explanation of variation than NEAT (or RMR).

Generally, when "slow metabolism" is mentioned here on MFP, I think people are referring to factors that are outside their personal control, at least in any reasonably short term sense. If that's the case, I think it could contribute to a general sense of disempowerment in the bodyweight realm.

I support this general method, definitely, as a calorie needs experiment to learn TDEE (not "metabolism" in the sense of BMR/RMR). That will give a more useful average TDEE estimate than any calorie calculator or fitness tracker. Also, 100% agree that the first week can be misleading.

But IMO one week isn't enough. Even fast fat loss - 2 pounds a week - is barely over a quarter pound of fat change daily on average. Personally, I've seen water retention shifts of as much as 6 pounds in one day, and I've seen others here report bigger water/waste fluctuations than that. That's extra true for some women who have monthly cycles. It's not the most common pattern, but there have been women here who reported only seeing a new low weight once a month, at a particular point in their cycle.

Those water/waste fluctuations can distort the usefulness of bodyweight scale information for a surprisingly long time, certainly more than a week, by masking fat loss on the scale. If weighing only weekly (or less) a person can even catch a relatively low weight on the first reading, and a high one the next week, not having seen the lowest weight they hit during the week.

I'd strongly, strongly suggest using a 4-6 week average on a given eating/activity routine, or at least one full menstrual cycle if that applies, before adjusting calorie goal.

Definitely using personal results is the best way of adjusting goals: Entirely agree about that. It's not perfect - even careful logging includes estimate - but it's the most useful available method.