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jjwalter2001's review against another edition
5.0
Walking at our most economical pace, about 2.5 mph, burns roughly 50 kcal per mile for a 150-pound person. We can think of that as an energetically optimal speed, since it requires the least amount of energy per mile. Walking faster, at 4 mph, will burn roughly 40 percent more energy, about 70 kcal per mile. At around 5 mph, the cost of walking exceeds the cost of running; it’s actually cheaper to run at that speed than it is to walk.
Our VO2 max, a common measure of peak aerobic power (see Chapter 8), is at least four times that of chimpanzees’. We carry more muscle in our legs (though less in our arms) than other apes, and we have a much greater proportion of fatigue-resistant “slow twitch” muscles. Our blood holds more hemoglobin to ferry oxygen to working muscle. And our naked, sweaty skin (by far the sweatiest on the planet) keeps us cool, protecting us from overheating even when exercising in hot conditions.
We are built for intense, all-day activity.
Our hominin bodies are also evolved to support, and in fact depend on, the high levels of daily physical activity that were the norm throughout the past two million years of hunting and gathering. We have evolved to require daily exercise. Without it we get sick.
Now the not-so-great news: their bodies were in starvation mode. By week 30, their BMRs had dropped nearly 700 kcal per day, or about 25 percent. The reduction in BMR wasn’t just a function of weighing less; it was far greater than expected from weight loss alone. The change was deeper. Their cells had reduced their metabolic rate, working and burning energy more slowly. And the changes weren’t temporary. When Hall and colleagues checked in with the contestants again six years after the show, their BMRs were still lower than expected. From a public health perspective, this seems perverse. Why were their bodies working against their efforts to burn off unhealthy weight? But from an evolutionary perspective, it makes all the sense in the world.
One standard measure of fitness for older folks is a 6-minute walk test, wherein a person walks as far as they can in (you guessed it) six minutes. Older adults who can cover at least 1,200 feet in that time have half the risk of dying in the next decade compared to those who can’t make 950.
When we put the daily energy expenditure measurements together with the data on weight loss, we found that every athlete (and pregnant mother) in our dataset was taking in the same amount of energy per day. Across the board, from the Antarctic trekkers to elite distance runners, their bodies were absorbing about two and a half times their BMR (just as we did with energy expenditure, we calculated energy intake as multiples of BMR to account for differences in body size). All of the energy expenditure above the two and a half times BMR intake limit was coming out of their fat stores, which is why athletes above that level of expenditure were losing weight.
The energy we pour into producing and processing our food transforms it from a source of nourishment to something more akin to a drug. The highly processed, flavor-engineered foods that dominate our supermarket shelves and commercials easily overwhelm our brain’s capacity to regulate energy balance.
Our VO2 max, a common measure of peak aerobic power (see Chapter 8), is at least four times that of chimpanzees’. We carry more muscle in our legs (though less in our arms) than other apes, and we have a much greater proportion of fatigue-resistant “slow twitch” muscles. Our blood holds more hemoglobin to ferry oxygen to working muscle. And our naked, sweaty skin (by far the sweatiest on the planet) keeps us cool, protecting us from overheating even when exercising in hot conditions.
We are built for intense, all-day activity.
Our hominin bodies are also evolved to support, and in fact depend on, the high levels of daily physical activity that were the norm throughout the past two million years of hunting and gathering. We have evolved to require daily exercise. Without it we get sick.
Now the not-so-great news: their bodies were in starvation mode. By week 30, their BMRs had dropped nearly 700 kcal per day, or about 25 percent. The reduction in BMR wasn’t just a function of weighing less; it was far greater than expected from weight loss alone. The change was deeper. Their cells had reduced their metabolic rate, working and burning energy more slowly. And the changes weren’t temporary. When Hall and colleagues checked in with the contestants again six years after the show, their BMRs were still lower than expected. From a public health perspective, this seems perverse. Why were their bodies working against their efforts to burn off unhealthy weight? But from an evolutionary perspective, it makes all the sense in the world.
One standard measure of fitness for older folks is a 6-minute walk test, wherein a person walks as far as they can in (you guessed it) six minutes. Older adults who can cover at least 1,200 feet in that time have half the risk of dying in the next decade compared to those who can’t make 950.
When we put the daily energy expenditure measurements together with the data on weight loss, we found that every athlete (and pregnant mother) in our dataset was taking in the same amount of energy per day. Across the board, from the Antarctic trekkers to elite distance runners, their bodies were absorbing about two and a half times their BMR (just as we did with energy expenditure, we calculated energy intake as multiples of BMR to account for differences in body size). All of the energy expenditure above the two and a half times BMR intake limit was coming out of their fat stores, which is why athletes above that level of expenditure were losing weight.
The energy we pour into producing and processing our food transforms it from a source of nourishment to something more akin to a drug. The highly processed, flavor-engineered foods that dominate our supermarket shelves and commercials easily overwhelm our brain’s capacity to regulate energy balance.
readnicoleread's review against another edition
informative
slow-paced
3.0
Some information that was new to me, like the constrained energy expenditure and effects of changing diet vs physical activity. A little technical but interspersed with amusing stories and metaphors, and ideas were summarized and repeated to help them stick.
chublaikhan's review against another edition
3.0
I learned some things. I knew some things. I scanned a lot.