We've been overselling what exercise does for weight loss (almost nothing) and underselling what exercise does for everything else. Even better if you can get your exercise outside.
Agreed. I’ve come to realize I don’t know anyone in my life who ever lost significant weight and actually kept it off permanently through exercise.
I go to the gym regularly and when I look around and see other women who have been working out for a long time, they are pretty much the same body shape I’ve always seen them.
Once you reach a new weight, that’s just your body’s new normal. I stress to people now that they should aim to never gain weight in the first place unless it’s muscle.
GLP-1 agonists are not exercise and thus using them would not change the calculus on how common it is to lose “significant weight and actually [keep] it off permanently through exercise.”
Nor does their availability change the validity of GP’s advice.
The idea that exercise doesn’t lead to fat loss is obviously false. If you’re eating a small surplus and increase your exercise volume you will lose weight. Clearly diet is a bigger lever, but plenty of exercises burn a lot of calories. Swimming and cycling are great for this.
Speaking as someone who, over a few years, lost about 50kg, the problem is that when I most needed to lose weight, my body couldn’t put up with enough cycling or swimming to burn useful calories.
I found it very funny that I spent about 2 years eating less so I could get better at cycling, then suddenly had to start eating more, once I was down 50kg, because I was getting faint on very long cycles.
Cyclists typically have enough energy stored up to ride for about 90 minutes without needing to refuel. For me it's 90 minutes on the button, and it doesn't seem to matter what I've eaten beforehand or how hard I push myself.
Its recovery keeping up with expenditure. -1000 cal deficits limit recovering from muscle/ligaments soreness leading to build up of stress that is more damaging than simply not eating
Your body rejigger caloric expenditure based on how much you exercise. It isn't a straightforward addition of physical activity plus basal metabolic expenditure.
Sure, you get more efficient but then you can just run a little faster or find a nice hill. If that’s boring go pick up something heavy. You can endlessly switch up training to find a thing you haven’t gotten used to yet. People act like there isn’t half a century of exercise science out there being put to use by athletes and regular people.
If you exersize a lot, your body will ask for a lot more food. Your body does not want to starve, and using a bunch of calories without replacement leads to that result.
At some point you have to control your diet. But, if you can control your diet, the exersize clearly isn't a requirement.
I find that’s only true for the first few months of training while you get the beginner gains. Running half an hour a day was by far the biggest contribution to my weightloss once I finished the couch to 5K program and my diet settled down. My body adapted relatively quickly to the new regime just like it did with my sedentary lifestyle but YMMV.
Once you can run frequently without gorging afterwards, the extra 300-500 calorie buffer makes dieting a million times easier.
(Lost 35 pounds in 2024, 90% of it during weeks in which I ran consistently)
> When you increase activity, over the course of weeks, the body adjusts and does everything it can to not touch those fat stores.
Your body doesn't adjust endlessly. The technique to continue to shift body composition is called progressive overload, this isn't outdated and is the basis of most athletic training regimens.
Again I want to reiterate that no one is suggesting that diet isn't the foundation of fitness and controlling body composition. I am simply and factually stating that you can use exercise as a lever to achieve a calorie deficit. Arguing otherwise is to argue against thermodynamics, moving your body consumes energy and you body simple cannot achieve perfect efficiency.
> TT and FT began to decrease starting 12 weeks in both moderate and high intensity exercise groups. Most significant decrease was at 12 weeks in high intensity exercise group
I hear this all the time from the exercise deniers and it makes me laugh, it's such a drop in the ocean compared to everything else that you will get by simply moving a bit more.
It's true. I jogged about 5-6 days a week for about 20-30 minutes a say a few years ago and the weight left me at a healthy tick. Naturally I could lose more with a better diet but I like eating so exercise it is.
Yep, if you were at stable weight before, it’s trivial amount of daily exercise to create a 500 kcal deficit which will have you drop 1 lbs /week. People who say exercise did nothing are either lying about amount or intensity of exercise or compensated with increased caloric intake
They never said that exercise doesn't lead to fat loss.
Only that it's a minor contributor and I would argue that's the case.
One of your examples, swimming, will put on weight as it will builds muscle mass which obviously is heavier. But one of the side effects of this is that your appetite will increase. And without careful diet management it's very easy for this exercise to be a net negative.
It's not a minor contributor though, people vastly underestimate how much exercise our species is adapted for, how much we're capable of, and just how far off from that most of us live.
It is, in quantities that are compatible with a modern lifestyle. Sure, if you're gonna run marathons every weekend, you will lose a lot of weight from that. But that's not possible to achieve while leading a normal modern life (full time employment, a relationship, children).
I think it is doable in a modern lifestyle, but that most people don't make it a priority.
Most people waste a shocking number of hours out of every day scrolling, watching TV etc, and just take it for granted as part of a "modern lifestyle", but it's just an optional way to spend time, and not very productive.
I have full time employment, a relationship, children, and manage to get our for 1hr of running almost every day. (And find time to debate with strangers on HN XD)
1h of exercise a day is great for your health, but that's still only going to be a minor contributor to fat loss. Adjusting your diet is going to have a much, much higher impact on weight loss than 1h of (moderate) exercise/day.
>The idea that exercise doesn’t lead to fat loss is obviously false.
People tend to offset that energy expenditure elsewhere in their life, often without being conscious of it. The body is really good at balancing out your energy consumption.
If I go for a 40 mile bike ride today then I'm pretty sure I'll zombie out in front of the TV tonight.
I think you need to exercise in order to get past a weight loss plateau though.
If you simply cut back on calories by 20% - 30%, your body will adjust to the new norm within a couple months, and you just expend 20% - 30% less energy. You have maintain some baseline activity levels in order to continue burning fat.
You can also train yourself on how you eat. When I was eating a Keto type diet, I was surprised at how my feelings of hunger between meals (two a day spaced at 8 hours between) disappeared. And how my tastes largely changed so that I didn't want other foods. However, it was easy to slide if I let it. Training back to the old was easier than training to Keto. I switch was just enough that I didn't have to keep myself in line with total discipline. But the path to sliding was still staring at me.
So, people don't necessarily need to diet. They need to train their appetite just like they train their body.
While that is a logical assumption, it’s not actually true. [1]
If you intake X calories, your body will use them to provide you energy for exercise. If you don’t exercise, you won’t always just turn it into fat - your body will find another find other uses of the calories such as producing stress hormones.
Exercise is important but will not make you lose weight alone.
No one is suggesting that you can out run an increasing calorie surplus. You can however keep your diet the same and add two hours of running to your week and lose weight.
Ask anyone who has been obese and subsequently lost weight and they'll tell you the same thing. Eating less is both a sufficient and necessary condition to losing weight. Exercise is neither sufficient nor necessary because the caloric surplus these people are on significantly exceeds the amount that you can practically burn through exercise. While you're right that exercise can help on the margin, it's just not a useful intervention that moves the needle much as far as weight loss goes.
I don't know why anyone here has the idea that I'm arguing that exercise alone is key for weight loss. I have very clearly only claimed that all else equal increasing exertion will lead to a calorie deficit.
> While you're right that exercise can help on the margin, it's just not a useful intervention that moves the needle much as far as weight loss goes.
There's more to exercise than just the thermodynamic effects of calorie expenditure. Building muscle and/or cardiovascular capacity will improve your quality of life and will complement any weight loss. You can improve your mental health by becoming more physically active, and this is well established. Those mental health gains and physical health improvements make it easier to maintain a better diet. Beyond the marginal, but significant calorie expenditures you can create a positive feedback loop.
At one stage, I started walking home from work at my fastest pace. 5 miles, 5 days a week. No other lifestyle changes. No significant weight loss.
A few years later, I started tracking calories with myfitnesspal and keeping to a limit (1600 initially, 1400 when it became easier). No exercise, but steady and impressive weight loss. I seem to have kept most of it off. I think a lot of it becomes psychological - not being afraid to feel appetite or skip meals if already satiated from earlier.
Only assuming you have a steady body weight and diet, which is a very bad assumption for most overweight and obese people.
Not to mention, the processes in your body are way more complex than all this makes them out to be. For moderate exercise, after an adaptation period of a few weeks to months, there is almost no calorie impact from the exercise itself on your total calorie expenditure: your metabolism adjusts and various internal processes are deprioritized to prioritize the exercise.
This is in fact a major component of why exercise is so healthy: it doesn't do much for weight loss, but it stops/slows down all sorts of unnecessary processes in the body that are actively harming your overall health.
> almost no calorie impact from the exercise itself on your total calorie expenditure
This is categorically false. You don’t have a magical metabolic adjustment, you simply become more efficient in performing an exercise but the calorie use never drops to effectively zero like you’re claiming. Think about this for a second, it makes no sense to think that running could ever consume zero calories, basic physics still apply.
I explained this very clearly. The exercise of course has to consume calories. But that doesn't mean they have to be calories in excess of your base metabolic rate. What happens is that your base metabolic rate decreases more or less commensurately with the amount of extra calories you're consuming through excercise. If your BMR was 2000 Cal/day when doing 0 calories from excercise per day, and then you start exercising for 300 Cal/day, your BMR will decrease to about 1700 Cal after some time of maintaining this routine.
And the newer work is starting to find the limits that I mentioned. There are several caveats that I didn't mention for brevity:
- no exercise vs moderate exercise vs athlete-level exercise are very different cases. Doing some exercise does increase total energy expenditure vs no exercise, but the amount doesn't change significantly until you get to pro-athlete levels. That is, going from 2000/0 Cal (BMR/exercise) to 200 Cal of exercise might take you to, say, 2100/200 Cal; but moving from 200 Cal of daily exercise to 400 Cal of daily exercise will not take you to a higher TEE; unless you reach the stage where you are doing, say, 1000+ Cal worth of daily exercise (specific numbers pulled from thin air, just trying to illustrate the concept).
- Muscle mass is a confounder for what I was claiming - more exercise leads to increased muscle mass normally, and that does lead to an increase in BMR very directly.
Overall the more correct claim I should have made would be "exercising more, assuming you are not very sedentary, will not lead to increases in total energy expenditure beyond those gained from muscle mass increase, unless you get to pro athlete levels of exercise".
I'm taking all of these links from the Kurzgesagt sources for their video on exercise: https://sites.google.com/view/sources-workoutparadox. They link to more specific claims from each paper, and to a bunch of other papers.
- one, your body may crave more food because of the energy loss - the Lipostat model suggests that your body has a target weight (well, fat level, more precisley), and will adjust hunger up if calory expenditure goes up
- your internal processes use way more energy than you can consume through exercise in a modern lifestyle (2000+ calories a day just from sitting still, for many adult males), and there is a lot of room for the body to adjust those up and down to make up for the extra exercise to keep up your current weight. So if you consume 2000 Cal a day with 0 Cal from exercise, with moderate exercise you will end up conauming 1600 Cal a day from internal processes + 400 Cal a day from exercise after some time (a one time run will absolutely consume extra, if your run every day, you'll get less and less extra Cal from your runs, until you reach about net 0, assuming you're not increasing the amount of exercise constantly).
If one were getting the doctor recommended amount of exercise running for 30 minutes or some commensurate activity would not be intimidating, and it's far less likely that you would have a weight issue in the first place. Doctors recommend about 150 minutes of moderate intensity exercise per week. Imagine doing that every week, for your whole life.
That’s why there are programs like Couch to 5K which slowly work up to a nonstop 30 minute run. It doesn’t even take that much determination and it’s practically designed for obese people. I was able to complete it weeks ahead of schedule at a BMI of 30 and the 4-5/wk runs it enabled helped me lose 35 pounds in 2024 - the vast majority of the weightloss happening during the weeks that I ran.
Nitpick: a marathon is 42 kilometers (by definition). Most people would struggle to even walk that.
There's no such thing as a 5km marathon, that's a contradicition in terms. However, if one were running 150 minutes a week on a regular basis then a (42km) marathon would likely not be too intimidating a prospect. Suffice to say, most are not getting in their doctor recommended level of exercise.
Agreed that life is not that simple as a math equation, but I think baselines apply, e.g. if you are sedentary, adding 150-180 mins of moderate exercise will definitely improve your health and life.
if you are already meeting that baseline, and still have issues, then you should look at tweaking other variables in the equation, whether diet, stress, etc.
What I find worrying is the cherry picking some people do, e.g. "aha your body will get used to exercise, so I might as well not bother", then wonder why at their next visit to the doctor, they are now told to go on a steady diet of statins etc.
The only thing being claimed is that exercise doesn't significantly help with long term weight loss.
That doesn't mean exercise isn't extremely important for your health. It is, in a myriad ways. Even the mechanisms that make it not help with weight loss are some of the reasons why it is so healthy - it's taking away calories from metabolic processes that are more harmful than helpful.
You're treating the human body as a far simpler system that it actually is, leading to drawing unsupported conclusions about the efficacy of exercise as an intervention for fat loss.
I guess if I'm totally out of condition then exercising feels very inefficient. Once I'm in condition, though, it's calories in = calories and it isn't complicated, at least for endurance activites. If I pile on more activity then I need a corresponding amount of extra calories and it's simple arithmetic.
I only see that study cited by people who are looking for excuses to not exercise.
You're off the mark here - I'm in great shape and exercise more or less every day.
At the same time, I keep up with the latest science and understand the limitations of exercise as a means of sustainable weight loss for the general population.
Please stop talking about simple arithmetic - the body is not a simple machine and trying to conceptualize it as such is willfully ignorant.
It's really not. Weight, atleast if you control for muscle weight, is an extremely good predictor of health issues at almost every level. It's a huge problem for your body both in many complicated internal ways, all the way to simple mechanical ways, putting increased stress on most of your joints and bones.
