fitness · weight loss

Feel the burn?: Sam mulls calories, exercise, and energy conservation

Many people ask me the same questions over and over again… What should I eat and what should I exercise like in order to look like the guys in the fitness:

So this morning, after two hours and fifteen minutes on my bike trainer in a super hard class, I looked at the information in a new light. Mostly I pay attention to average cadence and to max and avg heart rate, but today I also looked at calories–956 calories burned, it claimed–in a new light, given a study that was making the health and fitness rounds this week.

See More exercise doesn’t mean more calories burned

“Gym-goers might think that if they huff it on a treadmill for two hours every day, they will burn more calories overall than if they sneak in just 30 minutes.

But according to a study published Thursday in the journal Current Biology, as long as people are doing at least some baseline level of activity, they will expend about the same amount of energy each day no matter how much exercise they do — suggesting that exercise alone cannot be relied upon as a way to control weight at a time when the majority of American adults are overweight or obese.

For the study, a team led by Herman Pontzer sought to test whether energy expenditures increased as physical activity did, or if those expenditures plateaued no matter how much activity people were doing.

Researchers looked at 332 people in five different populations around the world: a mostly agrarian group in Ghana; people living in a township in South Africa; urban residents in Jamaica; island dwellers in the Seychelles; and suburbanites in the United States.

For about a week, they tracked physical activity using wearable devices akin to Fitbits, and measured energy expenditures through a specialized urine test.

They found that the amount of spent energy does increase with physical activity levels, but only in the low ranges of exercise overall.”

Here’s the study they’re talking about: Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans.


What do I make of the study?

First, I hate the reporting about it which mostly takes the form of “diet not exercise the key to weight loss.” See Why Diet Matters More than Exercise For Weight Loss, In One Video Why? Because the assumption is that the reason we exercise is weight loss. If that were my motive I would have quit long ago! See Why don’t plus sized athletes lose weight? for some discussion of this. I worry that it discourages people from getting active. Suppose they’re right, and there’s no reason to support the claim that they’re not, and diet matters more than exercise when it comes to weight loss. It’s still not clear to me that there is good evidence that diet works either.

Also, it’s not new news. See Science, exercise, and weight loss: when our bodies scheme against us.

Second, there are lots of good reasons to exercise that have nothing to do with weight loss. There are performance reasons, for example. I’m staying in bike shape over the winter to be able to do fun things next summer, like the Kincardine Duathlon and the Friends for Life Bike Rally. My reasons have nothing to do with weight loss. Indeed, I want to lose weight to be faster on my bike going up hill. There are also health reasons. Weight lifting/strength training, for example, is great for bone health even if it won’t help you lose weight.

Third, the research helps make sense of a puzzle we’ve blogged about here before, the athletes who work out hard but then flop the rest of the time. See Sedentary athletes, not a contradiction in terms and Children can be sedentary athletes too.

Fourth, and practically, it means that if we’re tracking exercise and calories the maximum we ought to count is 300 calories. That’s the actual difference researchers found between those who exercised and those who didn’t, regardless of what our instruments tell us. In light of that, let’s ignore the chart above. Let’s ignore the numbers on our Garmin. Bye bye calorie counters! But that doesn’t mean working out is not worth doing. Fitness matters more from almost every perspective. See Fitness and exercise are what matters, not weight loss.


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