Why exercise isn't much help if you are trying to lose weight

(newscientist.com)

31 points | by stevenwoo 12 hours ago ago

31 comments

  • edaus 9 hours ago ago

    Everyone seems interested only in weight loss. But the scale is just a poor proxy for what people actually care about ( looks, health or physical aptitude ). Your bodyweight remaining the same while gaining muscle should also be a huge win since that's building muscle, bone density and losing fat.

    Do people actually just want to lose weight momentarily through diet? Instead of keeping it off long term, which is way easier achievable through diet + exercise?

    Also no mention of body composition, bone density and cardiovascular health, which should be the actual metrics, instead of the proxy used for them.

    • fcpk 7 hours ago ago

      this is true for weight loss while in a mostly health range. it isn't true for people with high BMIs. for them the scale is a mostly direct match to health and how they look

      • yakikka 7 hours ago ago

        I think they are also at risk from the BMI simplification and the goal as presented in the article. The wrong crash diet approach can be raising their % body fat while lowering their BMI. If they weren't weight lifters that's probably putting them in a high risk group that isn't usually identified in studies.

    • undefined 8 hours ago ago
      [deleted]
    • LoganDark 8 hours ago ago

      I'm interested in weight loss because my BMI is over 30 which is considered obese regardless of whether it's muscle or not. I should not have a third of this weight. A couple years ago, I bought an electric scooter and it could not carry me because of the weight, so I ended up having to return it. Nowdays I have one that costs four times more and can carry me, but I still weigh much more than I should!

  • fcpk 7 hours ago ago

    human bodies are incredibly optimized to store energy for bad times and maintain a good balance at the ideal level. this is why the whole "calories in calories out" is technically true but mostly useless for a lot of people as the calories out is a very hard to compute variable. it also ignores entirely the negative effects of muscle loss.

    there is a lot of complexity and difficulty in long term weight loss, we are fighting biology hard there. that's why glp1 agonists are having such a success, they allow to fight hormonal homeostasis with proper weapons.

    I have yet to see any research showing a way to durably affect the body's set balance, which would be the revolution.

    but this research all in all confirms what we know: * high intensity muscle fiber tearing exercise is much better at not affecting metabolic compensating mechanisms * cardio might be good for health and other things, it's very much neutral or possibly negative for weight loss, as cardio does not build muscle mass * pure diet changes are difficult to make sustainable for many. I have seen it first hand where a constant 300 calories deficit a day resulted in weight gain and muscle mass loss despite cardio.

  • bob1029 7 hours ago ago

    Diet is king but exercise is not to be underestimated in its contribution.

    I have found major success with fasted cardio. That is to say, timing when the exercise occurs relative to your most recent meal seems to dramatically modulate the effects.

    If I do an hour of cardio within 12 hours of eating, it feels "normal". Nothing to write home about. If I do the same routine but I've been fasting for longer than 12 hours, I can feel my mitochondria light on fire after about 40 minutes in. The first few times I did this I stopped because I thought I was going to die. It felt super weird to me. Like a very strong parasympathetic response. You do get used to it though. I think this is one thing that can actually affect certain fixed points in your metabolism. If you go from zero to 80% VO2 max and keep it there for an hour on an empty stomach, that energy has to come from somewhere. And it has to happen pretty damn quickly. I think the time pressure for energy delivery under adverse conditions is what makes this so impactful.

    • zorked 5 hours ago ago

      > I can feel my mitochondria light on fire

      What is this supposed to mean?

    • edaus 5 hours ago ago

      What point are you even trying to make? The energy comes from your glycogen reserves and then from fat, both in a fasted vs non-fasted state. And if calories are equated at the end of the day, you just made your workout way harder because you didn't fuel properly.

      • weird-eye-issue 5 hours ago ago

        > you just made your workout way harder because you didn't fuel properly.

        Not necessarily. I feel way better when I work out in the morning without any food first. I think it's because my body doesn't have to spend any energy digesting food while exercising. This is true whether I'm doing a weightlifting session or a few hour trail run

        • fatherwavelet 4 hours ago ago

          It is because this subject is the closest to modern voodoo of all modern activities.

          I rolled the bones myself and it seemed like it worked, therefor X.

          No, I rolled the bones myself and it seemed like it worked, therefor Y.

          We would first have to define what we are even talking about by "energy" and "workout" to have any kind of real conversation.

          The popular mind on this subject is also not even up to the point we sequenced the genome. What people think of as truth is mostly repeating things from the 1990s.I rolled the bones myself and it seemed like it worked.

          • weird-eye-issue 3 hours ago ago

            Well I think it largely depends on how well trained you are because metabolic flexibility is something that gets trained. Without it your body has a hard time burning fats for fuel and so you'll feel terrible if you don't have an immediate glycogen store. When you are well trained you can do things like literally run several marathons while fasted which is documented. So whether it "works" or not will just depend largely on if your body has adapted to it

  • mint5 9 hours ago ago

    Egh pontzer and his misinterpreted studies again.

    Exercise burns extra calories, just not as much as one would expect based on simple calcs.

    At least this time the article is mostly okay, last article I saw here a while back was basically saying exercise doesn’t burn extra calories despite his works actually showing levels of activity influencing ~1,000 calorie difference in energy expenditure. Although speaking from experience, good luck trying to maintain high activity levels if one underfuels.

  • conception 9 hours ago ago

    You can run a marathon a month or not drink a coke a day or eat one less slice of bread. Exercise is important for your health but it’s not how one loses weight.

    • esperent 8 hours ago ago

      This ignores metabolism. If you are in a state of high caloric excess (i.e. you eat more than you need every day, like most modern humans) and then you reduce your calories a bit, you'll see some initial minor weight lots, but then your metabolism will simply compensate.

      To see real weight loss over a period of months you need to push past the point of metabolic adaption and stay there. Dropping a slice of bread won't cut it. That's why weight loss is so hard.

      That's why exercise is useful for weight loss even though it won't do much by itself. You'll need to use every tool at your disposal to burn those excess calories.

      • spicyusername 3 hours ago ago

            dropping a slice of bread won't cut it 
        
        But it will cut it, assuming you're moving your body the same amount every day. It just may take a while if you only cut a single slice of bread and you're wanting to lose a lot of pounds.

        Your body mass doesn't materialize out of nothing. Food in, body mass out. Less food in, less body mass out. Simple as that. Everything else is optimization that's not really required, just eating less, patience and consistency.

        • srean 33 minutes ago ago

          His point was when you eat more calories than you need, then the body can afford to be sloppy (inefficient) about absorbing all those calories.

          When you cut down a little on food but are still above or at your daily calorie requirement, the body can adapt by increasing its conversion absorption efficiency and in that case one wouldn't lose weight, because metabolically it's still absorbing the same amount of calories.

    • goworkout 6 hours ago ago

      A marathon a month is less than a mile a day. Semi regular exercise is an excellent way to burn some extra calories. Especially when your weight is relatively stable and your diet isn’t completely awful (so it’s not trivial to make huge improvements for little effort).

      This isn’t even getting into the many benefits of exercise in general, or the virtuous circle of "well I didn’t particularly enjoy that hour on a bike in shitty weather so I refuse to waste the benefit on a shitty donut purely out of spite".

  • blinded 9 hours ago ago

    No mention of cardiovascular health?

  • zeroCalories 10 hours ago ago

    This is just my own observations, but I find that when cutting calories I need to really optimize the rest of my life to avoid crashing in energy. Sleeping well, no alcohol, plenty of caffeine, lots of water and electrolytes, and time my carb intake. Doing a simple deficient will usually either not work, or lead to my energy completely crashing.

    • edaus 9 hours ago ago

      By how much are you cutting calories? At first glance it seems somewhat excessive if it affects your life so much. Also do you live in a very hot area or do a lot of cardio? Otherwise thinking about electrolytes is way too overrated

      • zeroCalories 6 hours ago ago

        I like to experiment with a variety of diets / deficits. On some of the more extreme ones like week long water fasting, or Lyle McDonald's rapid fat loss diet, you absolutely need to consume electrolytes because you're not going to get enough passively through eating. Personally I don't have a lot of success with very mild 200-400 calorie deficits, where electrolytes are not a major concern. I suspect it's due to factors related to the linked article, and that in general, the margin for error is much smaller.

        • edaus 5 hours ago ago

          It's probably because the calorie maintenance is a range and not a set number so you have to adjust accordingly so if you eat less -> you move less -> tdee goes down. All those while you feel lower energy and hungrier. That's where exercise comes in as a satiety regulator.

          If 200-400 kcals deficit doesn't work, just lower by 100 more each week until you get to a desired weight loss rate.

          I've found great success with this approach and also changing my thinking to 'is this thing something sustainable and healthy long term?'. Like of course I can lose a lot of weight fast with a huge deficit, but then I'll just default to my initial habits and gain it back.

          • vladvasiliu 4 hours ago ago

            I also find that exercise has an influence on my cravings and on what I eat generally. It basically makes it much easier to avoid stuffing my face with random calorie laden foods.

          • zeroCalories 3 hours ago ago

            I agree that it's a range, and that's precisely why it's hard to get right. If I go for a day trip on the weekend with my wife I might burn 1000 extra calories walking. If I have a mystery coffee at my friend's house I have no idea how much I just consumed. The margins are too close that it becomes difficult to make consistent progress.

  • stevenwoo 12 hours ago ago

    TLDR - your body compensates by using less energy in all other activities if you do aerobic exercise, more so if you cut back on calories in. This appears not to happen with weightlifting. They directly measured energy burned with doubly labeled water.

    • chistev 10 hours ago ago

      Is it more difficult to lose than to gain?

  • LoganDark 10 hours ago ago

    It sucks that losing weight is just impossible unless you change every habit you have instantly and totally and sustain that for the rest of your life. Otherwise your body will balance out anything you ever try to do in a way that makes it totally ineffective.

    • edaus 9 hours ago ago

      One could just start slowly with something like learning to make delicious food that's not as calorie dense or going for an activity like rock climbing or basketball with friends once a week instead of going to a restaurant.

      Yes, you have to sustain them for long periods of time, but that doesn't mean they can't be fun.

      • LoganDark 8 hours ago ago

        There's so much friction just getting to the point of even trying any one of those things that it just feels unattainable. Because you have to make it your whole life if you want to have any hope.