Lessons From a Summer in the Weight Room
This summer, I changed my exercise habits dramatically, swapping in three weightlifting sessions in place of my usual group exercise classes. I made the shift to support my new over-40 health priorities, which focus more on anti-aging strategies and less on bikini-readiness (full backstory here). My brother, a lifelong weightlifting devotee, stepped up as my coach. I was nervous about gaining fat or getting bulky as I chased my new goals, but my brother insisted that I would win on all fronts. We settled on an 8-week commitment, with license to revert to my old ways afterwards with no hard feelings.
As a scientist, I approached this challenge as a self-experiment, and was eager to know exactly what changes my body would undergo. In the weeks leading up to the ‘experiment’, I went nuts measuring myself every which way. I used everything from old-fashioned measuring tapes, scales, and fat-calibers, to fancy-schmancy metabolism tests and whole body x-ray (DEXA) scans. I measured everything more than once to ensure that I had a reliable starting point and to gain a sense of measurement ‘noise’.
Goal setting was next. I aimed to gain strength and muscle mass and to increase my bone density, all without gaining body fat. I set very specific goals up front for each parameter so that I couldn’t cheat myself.
With measurements and goals under our belts, we launched my new program just as summer began, declaring a “Summer of Strength”. For eight weeks, I stuck to my strength program religiously, executing three different whole-body workouts each week. The rest of my week was unchanged, and included a mix of group classes (HIIT style, spin), and solo cardio (swimming or walking) with the odd yoga thrown in.
For strength program details, see Wrestling with Philosophy.
Did it work?
The answer is yes… and no.
The good news is that I got much stronger, with the added perk of looking more muscular (anecdotal data only for the latter!). After 8 weeks, I could lift about 40% more in my upper body exercises (e.g. a change from 50 lbs to 70 lbs) and about 75% more in my lower body exercises (e.g a change from 100 lbs to 175 lbs).
The bad news is that my body composition didn’t change as I had hoped it would — no significant increases in either lean muscle mass or bone density (nor body fat). The key word here is significantly, because all measurements did change, but no more than you would expect them to if I hadn’t altered my exercise routine. I was able to distinguish ‘real’ changes from ‘noise’ using my two baseline measures. I had secretly hoped that I might also get a metabolic boost, but no such luck on this front either, though this is not surprising given the lack of change in lean muscle mass (one of the best predictors of metabolic rate).
What did I learn?
I’ve grouped my lessons into two themes: biological insights and broader benefits. Many of these lessons extend beyond my strength program’s original goals.
In reading my findings, please consider one major caveat — these are simply one person’s story. Others would likely have a very different experience (in fact, this is one of my lessons!).
1. Biological insights
Stronger doesn’t always mean bigger.
I was surprised by an apparent paradox — I got stronger but not bigger. Yet, experienced weightlifters were not surprised by my story. Apparently it’s common for beginners to gain considerable strength without much added size. I don’t fully understand the mechanisms but word on the street is that they involve changes in the way your muscles are wired and internally configured. More research to be done!
Boosting bone mineral density (BMD) is difficult.
This is an embarrassing confession for a scientist: I was so eager to get started on my experiment that I eagerly embraced the ‘common knowledge’ that strength training will benefit bone mineral density (BMD) without doing my due diligence on this topic. I should have been looking at critical questions such as: How much of a change can one expect? How long will it take? How different are results for pre versus post menopausal?
Now that I’m finally digging deeply into this topic, I’ve learned that my negative results are not surprising. For example, this review paper on resistance training in premenopausal women (such as myself) found an average boost of only 1% to lumbar spine BMD and no significant change in femoral neck BMD, across studies that were longer than mine. It’s also common to see large measurement ‘noise’ , such as the 1%-2% that I saw, which complicates change-detection. I haven’t given up on using resistance training to boost BMD, but realize that I need do more research before formulating my strategy.
Calorie afterburn rocks!
I was ‘prescribed’ to eat an extra 200 calories (including 20 grams of protein) per day during my program. Surprisingly (to me), I didn’t gain any weight — fat, lean, or otherwise. My hypothesis is that the ‘afterburn’ from my strength workouts was greater than that of my group fitness classes. The fact that my resting metabolism didn’t change supports (but doesn’t prove!) this hypothesis. It could also be that I was under-fueling myself previously, so that by boosting into a more moderate calorie range, my body was less likely to hang onto its calories (yet, I would expect this to be reflected in basal metabolic rate). Yet another topic for further research…
Don’t underestimate the power of genetics.
Even as a geneticist, I often forget to account for individual differences in how people respond to exercise (or diet, or any stimulus, for that matter). When I approached one of the strongest, most muscular women at the gym to find out her secrets, she credited much of her physique to genetics (with ample hard work layered on top!), telling me that most of her family was ‘built like a truck’. No offense to my big bro, but I think that genetics has stacked the cards against me for acquisition of bulky muscles. This is not to say that we can’t change our bodies, only that it can be useful to incorporate the context of your family into your expectations.
2. Broader Benefits
Increased mental toughness.
Due to the solitary nature of weight lifting, I was forced to hone my ‘ mind over matter’ skills and rely on myself for energy. As a group class junkie, I am used to feeding off of the energy from the instructor and classmates. In the weight room, I found that I could sometimes make a major jump in weights from one week to the next, simply because I put my mind to it.
Stronger outside of the gym.
I’ve been pleasantly surprised with how often the benefits of strength-training translate to other activities outside of the gym, such as biking uphill while pulling toddlers, or doing chair pose and other yoga postures.
Better back health.
A few weeks into my strength training, I noticed that my back was less sore than usual. My brother reported the same experience. It doesn’t strike me as far-fetched that a stronger back translates to less soreness from daily life (including lots of lifting toddlers!).
The value of knowing your numbers.
This experiment gave me a solid body composition baseline to use for long-term tracking, so that I can take action (where possible) to nip any declines in the bud. Ignorance is not bliss when it comes to aging, and the old jeans fit test can only tell you so much!
Given my family history of osteoporosis, I was thrilled to learn that I’m currently above average (75th percentile) when it comes to bone mineral density. This test gave me not only a tool for tracking changes, but also a peace of mind that I underappreciated until I had it.
The art and science of the self-experiment
This self-experiment dramatically illustrated several principles of how to design a successful self-experiment (fitness, nutrition, or otherwise). This topic warrants its own article to do it justice. Draft in progress!
What began as a “Summer of Strength” has evolved into a “Season of Strength”. Although I didn’t move the needle on many of the measurements that I hoped I would, I attribute most of this to the short time frame and remain committed to this path, and the broad benefits it offers (some already evident, and more to come). I hope that others will also walk away with a positive message and be encouraged to kick off their own Season of Strength.
While I love the feeling of my stronger self and the many benefits of weightlifting, I still prefer the experience of group classes. Thus, I’m tweaking my weekly routine to minimize iron-pumping time while (hopefully) not losing any ground. I’m trying out a new schedule of two weightlifting days rather than three, while reducing my number of repetitions (5–7) and increasing my weight load. In parallel, I’m researching how to optimize bone density gains and expect to tweak further based on my findings. Rest assured that I will be measuring and re-measuring myself every which way to keep myself honest!
See https://fueledbyscience.com for my growing collection of information and tools to help people make smarter, healthier choices.
Consult with your doctor if you seek to have medical diagnostic tests. All testing in this article does not require a prescription.