Tag: weight loss

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My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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Pretty cool study from David Nieman’s group at Appalachian State, just published online at Medicine & Science in Sports & Exercise. We’ve all heard the various theories about how exercise pumps up your metabolism so you’re burning extra calories throughout the day. The only problem is that attempts to measure this have produced all sorts of conflicting results, primarily because it’s such a pain to measure. You have to hook people up to complicated metabolic measuring equipment over and over, control for whatever random activities they do throughout the day, and so on.

This new study has two big strengths. One is a fancy, newly built “metabolic chamber” — basically a tiny room where everything that goes in and out is strictly controlled, including oxygen and carbon dioxide. Measuring the amounts of oxygen and CO2 going in and out (along with exact knowledge of the food going in and human wastes going out) allows the researchers to calculate exactly how many calories the subjects burn while they’re in the room.

And the second strength is that they were pretty hard-ass about the study protocol. The subjects (10 healthy young men) spent two 24-hour periods in the metabolic chamber: one where they did basically nothing, and the other where they did nothing except one 45-minute cycling session at about 70% VO2max:

At 8:00 am, subjects were sealed in the chamber and asked to stay in a seated position unless they needed to use the restroom or perform other necessary daily activities (e.g. washing hands, brushing teeth, etc.). Breakfast was served through an air lock passage at 9:00 am. On rest days, subjects remained in a seated position from breakfast until 12:30 pm when they were asked to get up and stretch for 2 minutes. On both rest and exercise days starting at 12:30 pm, subjects were asked to get up and stretch for 2 minutes every hour until 6:30 pm… Subjects were asked to remain in the seated position until 8:00 pm, at which point they were able to relax and lay down but not go to sleep. Bed time was at 10:30 pm, and subjects were asked to lie down even if they were not sleeping.

Hard core! Anyway, getting (finally) to the point: exercise boosted metabolism for the next 14 hours, burning an extra 190 calories in addition to the 519 calories burned by cycling (i.e. 37 percent extra). Note that it was vigorous exercise, which the researchers believe is important — some of the earlier studies that didn’t find any metabolic boost used more leisurely protocols (e.g. 50% VO2max). Here’s what the data looked like:

THANK YOU FOR VISITING SWEATSCIENCE.COM!

My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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The annual meeting of the American Academy of Orthopaedic Surgeons is taking place right now, and a press release describes five studies looking at the link between obesity and knee arthritis. There’s nothing particularly earth-shattering here, but I just like to highlight news like this because I still sometimes hear people who say they’d like to run but don’t want to ruin their knees — an idea that has been pretty firmly debunked.

“Other studies have looked at the effect that a combination of weight loss, diet and exercise had on knee arthritis, but it was difficult to say which of these factors contributed the most to reducing knee pain,” says Christopher Edwards, co-investigator and a fourth year medical student at the Penn State College of Medicine. “Our study should send a message to patients, health care providers, and payers that weight loss is an important consideration in the treatment of knee arthritis.”

That being said, it’s not as simple and obvious as you might think. The additional weight of being obese certainly puts extra load on joints — but there’s also evidence that fat tissue secretes inflammatory hormones that make joint problems worse. My wife is actually doing some research in this area at the moment… so if there are any big breakthroughs, I’ll keep you posted!

THANK YOU FOR VISITING SWEATSCIENCE.COM!

My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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I should state my bias up front: I’m a big believer in the importance of breakfast, fully indoctrinated by my mother from a very young age. So when I saw this press release, my skepticism ramped up to full power. It describes a new study in Nutrition Journal (full text available here) that analyzed the diets of 280 obese and 100 normal weight subjects for 10 to 14 days, concluding that eater a bigger breakfast led to greater overall caloric intake for the day:

Therefore, overweight and obese subjects should consider the reduction of breakfast calories as a simple option to improve their daily energy balance.

Heresy! Or is it… I decided I should at least read the paper. It turns out this is, indeed, a long-running debate. The authors of the new study, from the Else-Kröner-Fresenius Center of Nutritional Medicine (in Munich, where compound nouns are a way of life), argue that previous studies have been guilty of what seems like a fairly obvious error in interpretation. These previous studies have found that the higher the proportion of your daily calories you get at breakfast, the lower your overall caloric intake is that day. But these results are skewed by days when people choose to have unusually small lunches and dinners, the new study argues.

The details of this statistical debate are fairly intricate — and not that interesting, actually. Because the strongest arguments for breakfast were never predicated on the theory that you’d eat less later. It’s the other side of the energy balance equation that’s more interesting. By taking in the calories at the start of the day, you’re getting them right when you need them, rather than later when your physical activity for the day is done. You’re also getting your body out of starvation mode so that you’ll choose healthier foods and not store everything as fat when you finally cave in and have some food.

So what are the long-term effects of skipping (or not skipping) breakfast? A study in December’s American Journal of Clinical Nutrition followed 2,184 Australian kids back in 1985, and then checked in again in 2004-2006. The study looked for the effects of skipping breakfast as a kid, an adult, both, or neither. The results:

[P]articipants who skipped breakfast in both childhood and adulthood had a larger waist circumference and higher fasting insulin, total cholesterol, and LDL cholesterol concentrations than did those who ate breakfast at both time points.

Now, you might say that the people who skipped breakfast also happened to be Very Bad People in other aspects of their health. That’s a fair point — though the researchers do at least try to account for the possibility that the breakfast-skippers were eating trash for the rest of the day:

Additional adjustments for diet quality and waist circumference attenuated the associations with cardiometabolic variables, but the differences remained significant.

If you’re still not convinced, consider this final salvo, from the European Journal of Clinical Nutrition in September. Researchers at King’s College London analyzed the breakfasts eaten by 60 kids, then gave them a battery of cognitive tests. Now, it’s old news that breakfast makes you smarter. The new wrinkle in this study is that they broke the data down into four groups depending on glycemic index (how quickly sugars will enter the bloodstream) and glycemic load (glycemic index times portion size). The results weren’t entirely straightforward, but the best option seemed to be a low-GI, high-GL breakfast — in others words, have a big breakfast but make sure it’s not just a bunch of sugar and refined cereal or bread.

Last point: this isn’t carte blanche to totally ravage the breakfast buffet. In the study that sparked this post, one of the foods that contributed most to breakfast calories was cake (51 cal for the obese group, 132 cal for the normal group!). I mean, come on! If the Else-Kröner-Fresenius folks are advocating skipping breakfast to lose weight, then I heartily disagree. But if they’re just suggesting that you should go easy on the cake and sausages, then yeah, that sounds like pretty good advice — at any meal.

THANK YOU FOR VISITING SWEATSCIENCE.COM!

My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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Here’s one I hadn’t heard before:

Increases in winter indoor temperatures in the United Kingdom, United States and other developed countries may be contributing to rises in obesity in those populations, according to [University College London] research published today.

The claim comes from a new paper in Obesity Reviews (press release here), and on the surface, at least, seems plausible.

Reduced exposure to cold may have two effects on the ability to maintain a healthy weight: minimizing the need for energy expenditure to stay warm and reducing the body’s capacity to produce heat.

In particular, the authors note, exposure to cold is thought to stimulate the production of the famous but elusive “brown fat” that burns calories to generate heat. The paper itself goes into great depth about the proposed mechanisms and the expected effect size. Two graphs that I found interesting; first, indoor temperature trends in the U.S. and U.K.:

I love that U.K. bedroom temperature data! I lived in an unbelievably leaky apartment in Montreal for a couple of years — it was the former “coach house” behind a grander building, so it had no insulation. We were paying for our own heat, and had no money, so we kept the thermostat in the living room down about 13-15 C, and didn’t bother heating the bedrooms, kitchen or bathroom. We kept a “guest blanket” on the couch for anyone foolish enough to visit. And both my roommate and I were pretty skinny throughout those two years…

This is the crucial data — 24-hour energy expenditure as a function of temperature. Could it make a difference? Maybe. But before anyone gets too upset about this, I should note that even the authors of the paper aren’t proposing that this is the cause of obesity — they’re just suggesting it could be one of the many contributing factors.

THANK YOU FOR VISITING SWEATSCIENCE.COM!

My new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Also check out my new book, THE EXPLORER'S GENE: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, published in March 2025.

- Alex Hutchinson (@sweatscience)

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Weight loss is a pretty controversial topic, so I always expect to take some flack when I write about it, from people who are convinced they know “the truth.” (The fact that I hear from so many different people with so many different versions of “the truth” is a good reminder that it’s impossible to make everyone happy.)

I certainly don’t know the full truth about weight loss, but I did my best in Monday’s Globe article to summarize my understanding of the current literature. The most common complaint I’ve heard so far relates to my treatment of Gary Taubes’s ideas. Early in the piece, I referred to his latest book as an “anti-carb polemic.” Later in the piece, I wrote “Mr. Taubes’ core idea, that refined carbs cause a damaging spike of glucose that can affect insulin function (and thus fat storage) is backed by quite a bit of science.” To me, that seems like a fairly even-handed treatment — if anything, I’m coming down on his side. Nonetheless, I’ve heard from several people who say I’ve careless misinterpreted or misunderstood Taubes’s point.

For the record, I think Taubes’s critiques of existing nutritional orthodoxy are enormously important, and I made significant changes to my diet after reading Good Calories, Bad Calories. However, I also think he does exactly what he accuses his opponents of: drawing conclusions from epidemiological and mechanistic studies without confirmation from intervention trials. Or to put it another way, just because everyone else is wrong doesn’t mean Taubes is right and his orthodoxy can’t be questioned.

I had a very long and very interesting interview with Taubes a few years ago. In case anyone’s interested, here’s a transcript of one of the last questions I asked him. This question — and his response — is one of the reasons I don’t believe he has the “final solution” to understanding weight loss, diet and health.

AH: The last thing that I was trying to reconcile is the role of exercise. If you were to take a sample of 100 serious marathon runners, you’d have a fairly emaciated group who, traditionally, have been instructed to eat as many carbs as they can. Continue reading “Why I like Gary Taubes but don’t believe he’s the Messiah”