Let’s look at some fitness math
7 days a week, 24 hrs a day, let’s do waking hours, so 16 hours a day.
112 hours/week to potentially be active.
If you spend an hour in the gym, 3 days a week, that comes out to… 2.7% of the waking hours of the week.
An hour a day in the gym, 7 days a week—more than most folks do—comes out to 7.2% of your waking hours.
If you’re a gymaholic, 92.8% of your waking hours are still spent on non-exertional activities.
Expecting the 7.2% to make up for the rest is expecting a lot.
Your own percentage may be a bit better if you’re also doing major daily chores at home.
But unless you’re working on a farm, at most, maybe 10% of your waking hours are exertional hours.
Should more hours be exercise hours?
I started thinking about this anew after the Substack algorithm presented me with this really thought-provoking article by Erin Nystrom.
And the point wasn’t We all ought to move more.
The math makes that pretty clear. And conventional wisdom has been shouting this message for years.
– We’re all victims of technological ease
– Sitting is the new smoking
– Our forebears walked everywhere
There’s compelling evidence that exercise has an incredibly long list of positive health benefits, from reducing all-cause mortality, especially from heart attack and cancer (the top 2 causes of death), to improving brain function and mood. And that we aren’t getting enough of it.
The take-home of Nystrom’s article is that exercise as a weight loss tool does not work.
The conventional trope of burning off calories? Moderate-intensity cardio being better for fat loss than high-intensity sprints, or vice versa? Or lifting weights being better than either, to build more muscle to burn more calories at rest?
Observational science kinda says Nope.
The mic drop
The Hadza hunter-gatherers cited by Nystrom and in the Scientific American article she links to have a total caloric expenditure that is oddly close to ours, though they’re a ton more active. The men hunt and track all day to hopefully bring meat back, and the women forage for edible plants for hours—or the tribe doesn’t eat:
“But a funny thing happened on the way to the isotope ratio mass spectrometer. When the analyses came back from Baylor, the Hadza looked like everyone else. Hadza men ate and burned about 2,600 calories a day, Hadza women about 1,900 calories a day—the same as adults in the U.S. or Europe. We looked at the data every way imaginable, accounting for effects of body size, fat percentage, age and sex. No difference. How was it possible? What were we missing? What else were we getting wrong about human biology and evolution?”
“Following up on that work, Lara Dugas, also at Loyola, along with Luke and others, analyzed data from 98 studies around the globe and showed that populations coddled by the modern conveniences of the developed world have similar energy expenditures to those in less developed countries, with more physically demanding lives.”
There’s something of a universal human calorie burn homeostasis.
The kicker SciAm paragraph:
“All of this evidence points toward obesity being a disease of gluttony rather than sloth. People gain weight when the calories they eat exceed the calories they expend… evidence indicates that it is best to think of diet and exercise as different tools with different strengths. Exercise to stay healthy and vital; focus on diet to look after your weight.”
This explains the litany of every patient frustrated by unsuccessful weight loss: I work out nearly every day, and I haven’t lost a pound.
If you expend more calories of energy chasing and foraging—or spending hours and hours in the gym—your body reduces caloric expenditure for other physiological processes, like inflammation or cellular repair, to even out your total energy output.
Burn more over here, burn less over there.
And from the 30,000-foot overview:
“ Instead, with little fanfare or conscious effort, the camp deployed our species’ most ingenious and powerful weapon against starvation: sharing. Sharing food is so fundamental to the human experience, the common thread of every barbecue, birthday, bar mitzvah, that we take it for granted, but it is a unique and essential part of our evolutionary inheritance. Other apes do not share.
“Beyond our nutritional requirements and fixation with fat, perhaps the most profound impact of our increased energy expenditure is this human imperative to work together. Evolving a faster metabolism bound our fortunes to one another, requiring that we cooperate or die.”
As a species, we prioritize burning mega calories to fuel that big brain of ours. That’s what conferred a survival advantage and made cooperation smart, while limiting how much of a calorie debt we can incur through lesser activities like physical exertion.
We have always been the egghead nerds of the animal kingdom.
Thoughts
1. Ideal Movement has inarguable value, of many, many types. To keep your brain sharp, assist others, prevent premature death, avoid dependence, chase your grandkids, build with your hands, and defend against attack, you need to move and exercise.
2. But you still can’t outrun a donut. A calorie deficit is needed to lose weight, but the body limits how much you can burn off. To lose weight, you need to reduce the amount you consume.
3. Weight gain and loss are matters of what we eat. We can change several food variables: the amount we eat, the timing of when we eat, and the kinds of food we eat. But the lever to throw for weight loss and maintenance is dietary.
4. The majority of Americans will benefit from weight loss. Most Americans are obese or overweight. 40% are obese, 75% are overweight or obese, and if current trends continue, 2 out of 3 adults will be OBESE by 2050. Even those whose main interest is athletic performance will have an easier time being dozens of pounds leaner, to say nothing of the benefits to their health and longevity.
5. Biology is complicated. If you’re not active at all, a program to build strength and cardio endurance will likely help in your weight loss journey. So will neutralizing stress hormones like cortisol and insulin that oppose fat loss on a cellular level. So will cutting back on ultraprocessed foods that can stimulate foraging for empty calories.
Weight loss rarely boils down to one thing. Very little in life does.
We are in an unprecedented time in the history of humanity: most of us have the option to eat differently, including less, and to exert strenuously out of choice rather than harsh necessity. But what’s “natural” for us to eat and to do these days is no longer automatically varied and well-rounded.
Take-home #1: Your diet is critical. It’s not “the economy, stupid”; it’s all about the diet.
Take-home #2: In today’s brave new world, you have to design your health and fitness choices.
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