My weight and my body mass index are fine, according to the charts.

But if you take a deeper look inside my body, things don’t look so great.

I was never very strong to begin with (opening jars of Talk O’Texas Crisp Hot Okra Pickles has always been a struggle). It’s also common for people losing weight to lose some muscle mass at the same time.

Does it matter if my muscle mass isn’t optimal? I jump, I dance, I look fine in a size 6 dress.

Oh yes it does.

First, the good news. It’s never too late to get stronger. In one study among many others, subjects described as “frail nursing home residents,” aged 72 to 98, participated in a 10-week program of high-intensity resistance training.

The results: their average strength doubled (!), their walking speed increased by more than 10%, and their “stair-climbing power” increased by 28%. Nice job elders!

The bad news: muscle mass tends to decrease approximately 3–8% per decade after the age of 30, and the rate of decline is even faster after about age 60. See for instance this report .

Now take a look at this:

Over the age of 60 years, all-cause and cancer-associated mortality is twice as likely in individuals with low compared to high skeletal muscle strength.

– Biogerontology

Yikes!

So how am I doing? In my training, I’ve learned a lot about how to build muscle mass and strength. I know what to do, and I do it … sometimes. I started at a low level, but I’m gradually getting better.

Seeing some progress (I can do push-ups on my toes!) and having reached a good BMI, I figured that my body composition — the actual percentage of fat and muscle mass — must be getting pretty favorable.

On June 17, I went into the BodPod at George Mason University. (The BodPod uses Air Displacement Plethysmography, but there are lots of other methods to assess body composition; here’s an interesting page about it.)

What? 30.1% body fat? Where am I hiding it all? And after all this work, I’m not even (quite) in the “green zone” for my age? Oh no, am I the dreaded Skinny-fat?

Unfortunately, it seems that fat tends to gradually invade the muscles (“fat infiltration”). It also builds up around the abdominal organs, where it does nasty things like cause inflammation, in contrast to the relatively harmless jiggly stuff under the skin. (To check your visceral fat, measure your waist at the narrowest point: it should ideally be less than half your height.)

Look at these alarming muscle cross sections from three different guys (scroll down to the first graphic): a 24-year-old man, a sedentary 66-year-old man, and an active 66-year-old man. The two 66-year-olds are actually quite similar in weight. But the inactive man’s muscle is marbled with nearly twice as much fat as the other guy’s. (I bet his stair-climbing power is a lot lower too!)

Do I look like that on the inside … like a well-marbled steak?

I have work to do.

Oh yeah, I know how to lose fat — keto weeks, whole-foods-only, intermittent fasting, long hikes, it’s all in my toolbox.

“Don’t get any thinner,” my friends say, and they are quite right. I could easily become skinny and frail.

Muscle is the organ of longevity.

– Dr. Gabrielle Lyon

What I need to do is keep getting stronger, prevent muscle mass decline, and even push out sneaky infiltrated fat and recover some of what I’ve lost. So if I’m lucky, I can hope to have a longer healthspan: to live longer with a better quality of life (and keep my stair-climbing power).

A word to those who worry about “bulking up”: you can become strong and healthy long before you start seeing bulging muscles (if you ever do). I want to look like Ernestine Shepherd when I’m 80, how about you?

The path to greater strength and healthy muscle mass is not mysterious. Those intrepid “frail nursing home residents” showed the way with their 10-week high-intensity resistance training program.

I even truly enjoy working with resistance of all kinds — free weights, weight machines, bodyweight exercises, resistance bands, and especially water. Aqua Zumba with our unstoppable instructor Elvie actually counts as strength training, since I wear aqua resistance gloves and really thrash the water.

I’ve been following the “Muscle After 40” weightlifting guidebook from Men’s Health (at my gym with AirPods and a playlist of intense songs — music is definitely a key to my motivation). I feel great during and after every workout. But it’s a three-month program … I started at the end of April … and I still have three weeks left to go in the booklet. Oops.

It’s important to eat plenty of protein while building strength, and I’m becoming more aware of that too. Roughly, I should eat somewhere between 60 (my weight in kilos) and 130 (my weight in pounds) grams of protein per day. Do I do that? Not always. 60 grams is about three servings of meat, or four cups of chickpeas (!). A scoop or two of single-ingredient high-quality protein powder (like pea protein or grass-fed whey) helps.

I’m pretty sure that my no-car lifestyle during October and November has helped me build strength in my legs and core, with all the biking. [Update: I’ve decided to sell my car for sure; I’ve been walking, biking, taking the bus/Metro and occasionally Uber/Lyft, and just once borrowed my kind neighbor’s car to take the cat to the vet — and I’m now shopping for the right model of electric bike, input welcome!]

And during November I added to “Patricia’s Playhouse” at home, with this great no-installation-needed pull-up bar with hanging straps for inverted rows . I’m nowhere near a pull-up yet, but inverted rows activate my big back muscles and make me feel powerful. And so does this 40-pound kettlebell.

On December 9, I’m going back into the BodPod. I’ll share my results here, good or bad. Will I be in the green zone, or still in the yellow? (I’m not aiming for that blue “lean” zone. The “ideal” for my age, 28% body fat, would be great!)

Have I gained any muscle at all since June? Tune in soon to find out! But no matter what my new printout says, I’ll keep working. And learning. And even helping others (many of whom are stronger than I am), like my awesome “Fierce in the Forest” workout group.

Thank you for joining me on my journey! Please subscribe to future posts (above), and sign up for my monthly newsletter here to keep up with my other fierce activities. Thanks and see you next week!