Diet, not lack of exercise, drives obesity, a new study finds

npr.org

251 points by andsoitis 2 days ago


Delphiza - 2 days ago

Unsurprisingly, the title is sensationalist and not representative of the study. The study compares energy expenditure across different economic groups i.e. western people sitting in offices versus hunter-gatherers in Africa, and found that difference in energy expenditure does not account for differences in obesity, so points to consumption as the likely reason.

The sample dataset explicitly excluded 'athletes', so would exclude people that _are_ outrunning a bad diet. We know that a little weekly jog around the park doesn't mean you can eat a cheesecake every day, but anyone who has done extensive 'athletic' physical activity knows that if you don't up your calorie intake that you will lose weight. The study does not conclude, at all, that you cannot outrun a bad diet. Instead, it suggests "that dietary intake plays a far greater role than reduced energy expenditure in obesity related to economic development."

Edit: My point is specifically not about running. I am merely pointing out that if you read the study you will find that it is more of a study on economic development, and not really useful for personal or localised health advice. It observes that economically developed population groups may be more sedentary, but do not expend significantly more energy - so a hunter-gatherer picking berries all day does not burn significantly more energy than an office worker (at least not enough to explain why the office worker is obese). Therefore, the link between economic development and obesity is likely related to food (dietary intake) than daily activity.

tonymet - 2 days ago

For most people, a 1 hour moderate run is only about 1-2 cookies worth (and only half a Crumbl cookie). Even a marathon run might only burn 2000 calories . a chipotle burrito is 1600 .

In other words, for 95% of people doing activity, they shouldn't eat any surplus if their goal is to maintain or lose weight.

It's actually best to do most of your activity undernourished, as it helps develop true intuitive nutrition feedback sensation. You'll start to sense how every macro and salt feels when you ingest it. Loss of this sensation is a major obesity driver. A numbness for nutrients.

bko - 2 days ago

> "So if we burn more of our energy every day on physical activity, on exercise, after a while our bodies will adjust and spend less energy on the other tasks that we sort of don't notice going on in the background," Pontzer says.

I also think this is true related to food. Your body adjusts its metabolism based on the amount of food you eat as long as it's not chronic. That's why you can have competitive eaters that can eat a weeks worth of food and not be overweight. Spikiness and variability are probably good for you. Its funny that the Bryan Johnson types who closely control every calorie in their body have such a bad reaction to any variability. I don't know if its him, but I heard someone not be able to sleep and their levels got all messed up from one sweet. And their conclusion was sweets are so bad for you, rather than you're building your body to be too fragile to shocks.

The interesting thing is when this breaks down. Obviously if you eat a weeks worth of food every day for a sustained period of time, you will start to gain weight. Or if you run 12 miles every day, you will be in such a deficit that it won't be possible to lower your metabolism enough. Outside of the extremes, I think it's a cliff, where you have to have some kind of shock for some period of time for your body to react.

SeanAnderson - 2 days ago

Diet to manage your weight. Exercise to manage your fitness.

It's real simple in theory and real difficult in practice. Super worth it, though. Your entire world starts opening up when things take less energy to do and you have more energy to give. It's very challenging to convey how important it is without living the experience.

com2kid - 2 days ago

This is true to an extent and I'm very fond of the saying, but beyond a certain point you can indeed outrun a bad diet.

I used to spend ~4 hours a day training martial arts (kickboxing, BJJ, etc) during which time I could eat almost anything I wanted without gaining weight.

I'm sure if I had downed a cheesecake a day it would've been bad for me, but I was able to get away with a level of excess back then that I am unable to today.

So you can indeed outrun a bad diet, it just takes more running than most people want to do!

ozgrakkurt - a day ago

There is a psychological method that I found to be very helpful. Thinking of companies that sell packaged foods as your adversary.

They want to take your health, make you addicted to what they are selling and also take your money. Not very different from a drug dealer.

When in this mindset, avoiding these things feels like winning and taking care of myself, don’t need to worry about if sugar is really bad or if eating these things is normal. Or if I deserve a treat after working hard all day etc.

After some time I just keep winning and losing weight and don’t really have any cravings to eat bad “food”.

And fruit tends to be cheaper than packaged food too.

post_break - 2 days ago

Having lost 40lbs in the past couple of years, diet and walking have been key. It's just so much easier to burn fat by not eating it, than it is to try to burn it off with exercise. You'll find that burning 500 calories on a treadmill feels like an eternity, but eating one chocolate chip muffin? You can do that and gulp down a big glass of milk in 5 minutes like it's nothing.

benabbott - 2 days ago

Whenever the topic of weight loss comes up, I always make the same recommendation: Lift weights. Lifting weights increases your muscle mass. Muscle burns calories, even at rest, which raises your TDEE. (A bodybuilder will burn more calories sitting on the couch than someone who doesn't lift weights). For most folks (myself included) cardio sucks. You _could_ jog for an hour every day and burn x-hundred calories due to the increased energy expended... Or you could go lift weights a few times a week, and after a couple months, naturally burn more at rest due to increased muscle mass.

I say this as not a nutritionist nor a doctor, but I don't believe I'm off base here. Feel free to correct me on this if I am.

RobKohr - 2 days ago

I cut out drinks with sugar in them, eating after dinner, and in general just eating healthy meals.

I lift weights about 3 days a week, and am fairly fit strengthwise.

All this lowered my fat levels down to a reasonable level, but still left me with about 23% body fat and a bit of a belly, and that remained consistent. Trying to diet didn't really cause any maintainable change.

What I found has helped is doing a 24 hour fast once a week. This really means just eating one dinner a little earlier (4:30pm) and then skipping breakfast and lunch and drinking water with electrolytes added.

With keeping the rest of the days calorie intake the same, I have shaved off consistently 1 pound a week and 1/2" from my waistline.

This has been going for 5 weeks now, and I have gone from 23% to 19.7% based on navy body fat formula.

What is great is I have no cravings or feelings that I am depriving myself except for the last 8 hrs of the weekly fast. The rest of the week, I eat well.

My plan is to bring myself down to 15% and then continuing to measure. If I get above 15% I fast that week, if I don't then I don't fast, so it basically becomes like a controllable throttle.

josefrichter - 2 days ago

I thought this is common knowledge.

1 Snickers bar = 30 minutes of running.

You can lose 100 pounds without getting up from the couch, but you cannot lose 100 pounds by running, if you keep eating Snickers bars.

71153750 - 2 days ago

This reminds a little of Usain Bolt famously having chicken nuggets before his final at the Beijing Olympics. Although hardly indicative of a bad diet that he may or may not have had.

I think as well there is some difficulty with variability between people that isn't clear or maybe doesn't matter at scale. The article linked study was across 43 nations with 4213 adults. Yet there may still be individuals who can argue differently. CICO (calories in vs calories out) must apply to us all, but the composition has an affect on what the body chooses to store vs how energised or hungry/satiated we feel. A bad diet could perhaps me we feel we have less enthusiasm for running or other activities. Age, lifestyle, and even cultural factors are massive in affecting metabolism (more the foremost) and of course what we consume (the latter two).

I run a fair amount (over 2000km/1200 miles in 2025) and find that once I start doing above ~70km/43 miles in a week whatever eating habits I have are indeed outcompeted by my running and weight loss is inevitable. Even so it does slow around a BMI of 23 for me for longer than I am able to be consistent with the running to observe further effects. Still my point is that my diet isn't anything to write home about and I anecdotally I feel that as far as weightloss is concerned I can very much outrun it.

regnull - 2 days ago

Anecdotal evidence: I found that it's super easy to eat way more than you should by just having some food laying around. And I don't mean just Cheetos - "healthy" food will set you back rather quickly as well. The amount of exercise doesn't matter that much - with the calorie density of common snacks, you will out-eat your exercise really fast. I don't think I'm that bad in that sense, but until I started keeping a track of what I eat and the count the calories, nothing worked. Yes it's a hassle, but I vibe-coded an app that does image analysis and tracks your calories. Shameless plug: HeartLens on app store, https://apps.apple.com/us/app/heartlens-your-health-tracker/...

speby - 20 hours ago

I think it is very easy for the average person to forget or not realize how incredibly easy it is to get calories into the body and how little food is necessary to do so. Most people in the world (I know, this is not everywhere and everyone), live in an era of food abundance. It's cheap enough, extremely accessible, often easy to eat or ready to eat, and that has simply made it very convenient to get calories in, often while barely thinking about it. Mindless eating, not thinking about what you should eat, etc. All of these factors have played into why obesity is such a problem (at least in the USA).

JKCalhoun - 2 days ago

I have been, rather lazily I suppose, trying to tweak my diet in such as way as to lose weight; and with little to show for it.

I'm not sure that there is much if any processed food still in my diet (maybe just the English muffin in the morning?). I stopped buying/drinking soda pop decades ago (a low-hanging fruit indeed — I lost almost 10 pounds within a month of making that dietary change alone).

And since I have tried little things like switching to peanut butter that contains only peanuts (no salt, no sugar, not palm oil — sure, I have to stir it when I open it for the first time). I've moved to whole grain bread. Other small changes like that I can't remember right now.

I still have a BMI that's too high.

The only time I have significantly lost weight was when I was prepping for intestinal surgery nearly a decade ago. I was at the time worried that eating too much would literally kill me (I was worried about bursting my intestine) that I ate very small portions for each meal.

I'm not sure why I can't change my habits such that I continue to eat those small portions (now that the fear is gone).

nunez - 2 days ago

Maybe I'm reading the study wrong, but it doesn't seem like they accounted for caloric intake at all? https://www.pnas.org/doi/10.1073/pnas.2420902122

They accounted for total EE and basal EE, but the data they've supplied in the appendix doesn't track caloric intake.

This seems like a huge miss to me, as it is absolutely possible to have a sky-high TEE while being insanely fat (American football linebackers) and also having a low TEE and being skinny as a rail (by basically not eating, i.e. most fad diets).

Also, they categorize most of Africa as either horticulturalist, agropastoralist (why couldn't they say "farmers"???) or hunter-gatherer) despite the table at the bottom ranking their economies as "lowHDI", and the BEE for this cohort is N/A, which invalidates their PAL ratio (TEE/BEE).

idk this seems like a "fat ppl bad" study to me.

momocowcow - 2 days ago

Nice clean journalistic blurb from NPR. Case close! Too much food makes you fat, not genetics. Until the next article in a month.

Lerc - 2 days ago

I think it is fairly accepted that most of the health benefits of exercise apply regardless of your weight loss.

SirFatty - 2 days ago

Something my doctor has told me on more than one occasion, be he was also quick to add a statement about the importance of exercise for overall fitness. But.. want to lose weigh, change your diet.

bfrog - 2 days ago

Any athlete really knows this to be true. You don't lose weight running/lifting/biking, you lose it in the kitchen.

Multi-day hiking forces the issue as you have to carry the kitchen on your back.

larrik - 2 days ago

More data: I once lost 80 pounds purely through dieting. I really didn't change my exercise habits at all throughout (vs before I dieted).

I was partially testing this theory, in fact. This was a decade ago, but I was aware of this line of thinking at the time. Specifically, that dieting is more important for losing weight, and exercising is more important for being healthy (losing weight alone really didn't make me noticeably healthier, btw).

I found that, for me, this was entirely true.

cluckindan - 2 days ago

The more processed foods one eats, the more one is exposed to PFAS and plasticizers with endocrine activity.

That is the smoking gun here, not the amounts of calories people are eating.

mousethatroared - 2 days ago

Our resting metabolic rate is pretty high. Turns out livers, and brains use a lot of calories.

But the value of exercise is that you form more capillary structure to oxygenate blood

71153750 - 2 days ago

Somewhat orthogonally related, I saw post on X by Nassim Taleb [1] concerning the idea that if you are very active then your heightened consumption of food may cover your nutrient bases better. So perhaps, loosely paraphrased, you could outrun and thus out-eat your nutrient imblance?

1: https://x.com/nntaleb/status/1684885140093206528

kingstnap - 2 days ago

Everyone in bodybuilding or adjacent crowds already knows this.

How fat you are is entirely a function of how much you eat. If you want to put on weight, you bulk by eating more. If you want to lose weight, you cut with reduced calories.

The idea you could instead bulk by doing less cardio and cut by doing more sounds completely crazy. In reality, you do more exercise on a bulk because, duh, you can recover from more volume when eating a surplus.

siliconc0w - 2 days ago

If you eat 4k calories but burn 5k, you'll lose a lot more weight than if you ate 1000 and burned 2000.

So running can help but you still need a calorie deficit. Eating and burning more boosts your metabolism - if you measure a body builder during a bulk they are like a furnace, burning 1-2k over baseline. They still put on fat but it's a lot less than what you'd think given the amounts they're eating.

laurent_du - 2 days ago

At some point in my life I was eating 400g of nutella every day. I was also running 26km per day. I didn't get fat.

roguecoder - 2 days ago

In twin studies the only things that have been associated with obesity are past calorie restrictive diets and soda consumption. All these other studies are usually picking up on either socio-economic or environmental factors, rather than actual behaviors we can control.

The reason to exercise isn't to avoid obesity: it is because the health benefits of exercise have nothing to do with weight. Careful, moderate exercising is good for our bodies, all on its own.

Whereas there is shockingly little evidence that obesity itself causes most correlated health conditions, rather than being a symptom (of stress, alienation, environmental contamination, inflammatory conditions, etc) correlated with the causes of those conditions. The weight with the lowest all-cause mortality is being "overweight".

But of course, "work less" is a lot harder to make money off of than "lose weight", so any science that can be twisted to prop up the weight loss industry will get spread far and wide.

blu3h4t - a day ago

I just lost 50 kilos in 10 months. Quit sugar, walk 10km a day and most importantly ate almost only soup. So kind of low carb vegetable oriented stuff.

hermitcrab - 2 days ago

The only time I ever got close to having a 6-pack was from 16 days trekking in the Himalayas, culminating in summitting Mera Peak (~21,000 ft). I did not reduce my calorie consumption. But it was just a temporary change.

Beijinger - 2 days ago

Deja vue, but it is really a new article.

There are older studies: Epub 2015

It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet

https://pubmed.ncbi.nlm.nih.gov/25904145/

SirMaster - 2 days ago

You can, it just takes work and discipline.

For example jogging at about 7mph for 2 hours a day for a 180lb man would burn about 13,200 calories a week. I know people who jog like this.

Or I know people who cycle 250-400 miles a week which burns about 17,000-27,000 calories a week!

tartoran - 2 days ago

I personally lost some weight and am now lean by simply changing my eating habits to intermittent fasting. I got so used to it that now it's effortless to continue.

xacky - a day ago

I worked a physically active job from 2003-2015 and was still obese.

mglvsky - 2 days ago

Neither good diet can solely help avoiding to be skinny-fat

edit: grammar

kazinator - 2 days ago

We already know that in "thin countries", it's not that way because of everyone exercising like mad.

lizardking - 2 days ago

Abs are made in the kitchen, as they say.

mullingitover - 2 days ago

There is a simple and very low-impact exercise which affects obesity: the fork put-down.

Steven420 - a day ago

This has been known for a very long time and is definitely not news worthy

alberth - 2 days ago

I know this can be a touchy subject, but honestly, it shouldn’t be surprising.

It’s just basic thermodynamics.

The energy (calories) you take in has to go somewhere. Some of it gets used for daily activity, but if you take in more than you burn, your body has to store the extra—it doesn’t have any other way to deal with it.

At the end of the day, it really is just a matter of calories in vs. calories out.

Exercise just helps burn more of your excess energy so that it doesn’t get converted into (weight) storage.

https://en.m.wikipedia.org/wiki/Laws_of_thermodynamics

lrvick - 2 days ago

I do not have time for lots of exercise beyond the occasional walk but I hated that I was 40lb over my healthy/ideal weight I used to be. So I simply ignored all the tactics of others in my life chronically struggling to lose weight or keep it of and did the research on the Standard American Diet.

All data pointed to Americans simply consume way way too many processed foods, carbs, and artificial sugars. No one should be surprised, but no one wants to change this because shit food tastes so good. I simply dropped all high processed foods, dropped to about 100g of carbs a day, and cut out soda completely. All the extra weight fell right off over 6 months. I did nothing else. Also my dopamine response has changed and healthy food and canned sparkling water now feels as good to consume as fast food and soda used to.

Meanwhile friends with the same problem try lots of exercise and never lose any weight, and others use ozempic with no diet changes and also lose no weight. No one wants to hear they have to do something as hard as a permanent major diet change, but blame biology and terrible nutrition education. I am just the messenger.

YMMV, but my own experience certainly agrees with this study.

Commit to stop eating like an overweight American long term and you are likely to stop looking like one.

amai - 2 days ago

Run 10 km 4 times a week and you will loose weight. Try it or your money back!

nixass - 2 days ago

It's dead simple.

Calories deficit makes weight loss, everything else is laziness

- 2 days ago
[deleted]
0xbadcafebee - 2 days ago

In other news: a group of scientists announced today the results of their recent study, where they conclude that drowning is not caused by a lack of swimming, but instead seems to be due to water. Other scientists have refuted the claim and point out defects in the study criteria. In response, US officials have pulled funding from the National Science Foundation for any further studies into the causes of drowning, calling any claim of drowning that doesn't end with the sentence "the will of God" as unpatriotic.

just-working - 2 days ago

Calories in, calories out: the pareto-optimized answer to weight loss

reassess_blind - a day ago

Calories in vs calories out. This isn’t news.

sophia01 - 2 days ago

The title is disappointing: it implies a causal relationship. The study was an observational study.

Indeed, you can outrun a bad diet: we all know that. The study just shows that the lack of activity isn't the main reason for obesity. Both things can be true simultaneously.

Whatarethese - 2 days ago

Calories in vs Calories out. Just stop eating so much.

taeric - 2 days ago

Reminds me of a video I saw recently that pointed out the absurd number of calories professional athletes burn. Upshot of that video was that you almost certainly can run to lose weight. Just don't expect it to be an easy task.

At a personal level, I can also say that it is flat out hard to eat large amounts of food if you are staying active. The stereotype of wanting an after meal nap is legit.

It is also somewhat interesting to see other places try and contend with just how much food your average person in the US has at their ready disposal.

mrandish - 18 hours ago

N=1 but I lost over 100 pounds in 8 months by changing to a keto diet with zero exercise (consciously going even more sedentary than I already was) and have kept it off for over eight years now. After I reached my ideal weight I restored exercise to my previous normal level (which is minimal but not absolutely sedentary). After a year I slowly transitioned from strict keto to low carb for life.

I feel great, look good and my health improved dramatically. Before changing I was on meds for pre-diabetes, high blood pressure and poor HDL/Trig along with having bad apnea and tectonic snoring. All resolved after 8 months and still off the meds today. In the prior decade I'd spent a lot of effort and money trying various diets, including medically supervised, but they were hard, stressful and none worked long term. Even though I've never been athletic or remotely a gym-rat, intentionally going sedentary was an unusual choice because I'd always heard "eat less, move more" but exercise made me hungrier. So when I got serious about doing keto hardcore, I decided to pause even the minimal token "faux exercise" like an occasional pleasure bike-ride or short walk on weekends.

Frankly, that occasional, brief exercise probably never did anything in terms of weight loss anyway but it did provide a psychological excuse to slip on diet. So eliminating that excuse and putting all my focus on diet may have been the main benefit of going zero exercise during my weight loss period. After I got below my target 'dream weight', I returned to my usual minimal exercise and since then it's increased even more because now I actually enjoy exercise. It turns out that exercise is a lot more fun when you're not obese and winded after 90 seconds! I think Keto worked for me when other diets hadn't because it's so strict but also brutally simple. I've also always liked the low carb foods like meats and cheeses.

As a significant and long-term success case, I'll share my personal "keys to keto success": 1. Commit to doing it hardcore for at least 30 days. 2. Rigorously track every molecule of food intake in a tracking app for the first month. Yep, get measuring spoons and a kitchen scale for weighing things. Think of it as a cool lab experiment and you're the rat. Get used to cooking at home and bringing lunch to work until you get the hang of the low carb lifestyle. 3. For the first week do not track calories, just limit carbs religiously. Seriously, stuff all the calories you want. Steaks drenched in butter and sour cream, a quarter pound of cheddar, whatever. Why? The first week is the hardest and this makes the transition easier. The calories will be much easier after you get control of your blood sugar by limiting carbs. 4. You MUST supplement electrolytes (sodium & potassium) for at least the first week. "Keto Flu" is real, excruciating and so easy to avoid. I didn't take all the warnings seriously and failed my first attempt at keto in utter misery after just 38 hours. 5. Start on a quiet weekend where you can just focus on this from Fri afternoon to Mon morning. 6. Absolutely, positively DO NOT CHEAT on carbs for the first 30 days. Keto is different because the first 3-ish days of transitioning off carbs are pretty hard. If you cheat, you'll keep having to redo some or all of that transition over and over. It's like crossing a wall of fire. You can get through it fine the first time with focus and planning but you definitely do not want to be wobbling back and forth through it. Keto works because strictly limiting carbs controls blood sugar which reduces hunger making cutting calories much easier. If you need to cheat, cheat on calories not on carbs.

It's not as hard as it sounds. Just get past the first month and it all gets a lot easier. The results come fast. I lost 10 pounds in 10 days and 20 pounds in 30, which provides a lot of motivation! At around six weeks I became 'fat-adapted' which is a long-term metabolic transition to primarily burning fat instead of carbs (glucose) for energy. It felt absolutely amazing in every way - physically, mentally and emotionally, like nothing I'd ever experienced before. I was mentally sharper, physically quicker and emotionally more grounded in a positive mode. Everything just felt and worked better in subtle but tangible, meaningfully real ways. It made me never want to go back to living inside a primarily carb-adapted metabolism. Of course, I hadn't physically craved carbs since the first month and by around 60 days my old habitual eating patterns and reflexes had faded. Then at around 90 days my palate shifted, meaning I even lost my taste for carbie foods. If I tried a small bite of something carb-laden that I'd loved my whole life, it didn't even taste particularly good to me anymore. I also became hyper-sensitive to sugar. Sugar-soaked foods just taste poisonously over-sweetened (which they kind of are). A normal apple now tastes as sweet as I'd ever want, like a dessert that has extra sugar-added.

For most of my life my weight was a metabolic mystery seemingly out of my control. Today, it's hard to even remember what it was like being a slave to my raging blood sugar and constant hunger. Now I feel closely attuned to my body. This makes my weight and appearance an almost trivial conscious choice. Fortunately, going low-carb is a lot easier today than when I started in 2017. There are many more delicious low-carb food choices at the grocery and everyone has heard of keto so it's not as weird. Even Wal-Mart has a selection of keto-breads and, recently, bagels! Standard disclaimer: Every metabolism is different and what worked so effectively for me may not work as well for you.

specproc - 2 days ago

I'm from a western country, but live outside the OECD. Currently on a trip back home and the food is disgusting.

Everything tastes sweet, is invariably hyper-processed, and supplied by a narrow pool of companies.

My diet in my host country isn't great, but it's so much easier to eat well. Fresh fruit and veg is more readily available, cheaper and frankly tastier. I wouldn't say people are any more or less sedentary, particularly in the capital city in which I live.

The study is supported by my limited experience.

Barrin92 - 2 days ago

It ought to be obvious. A chocolate donut, large Frappuccino or pick your unhealthy food of choice are about equivalent to half an hour of running. Given how many people throw in a snack like that several times per day good luck burning that off with exercise.

One of the most straight forward things to lose weight is just limiting yourself to two or three actual meals, black coffee, tea, etc.

a3w - 2 days ago

The timing of when I eat changes, if I gain weight. Eating pizza after jogging? Fat on belly.

Eating as much pizza as I want, but going to bed after on empty stomach after running, or putting the running in the morning while doing about 12 to 16 hour slots of intermitted fasting? Hello, six-pack.

testing22321 - 2 days ago

I’ve been thinking about writing a book on this topic: “No overweight person eats well”.

By very definition of a person is overweight, they got there by eating poorly, and are continuing to do so. They have eaten more energy than they use, this energy storage in fat.