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Scientist busts myths about how humans burn calories

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Re: Scientist busts myths about how humans burn calories

#571

Post by ddorian43 »

rob74 wrote: post #407
artdigital wrote: post #378

Earlier quoted context omitted.

My advise: (as someone who does a lot of working out and calorie control) Write down what you eat for a while and its calories. Weigh yourself daily as well and write that down too. If after a week your weight went up: Your calories are above your TDEE. If it went down: Your calories are under your TDEE. And that's basically it, once you know what your TDEE is, eat under it to create a caloric deficit and you will lo…

Of course, eating less is the ideal solution if you can muster the willpower to actually do it - but that's a big "if" for many people...

Just do keto diet or carnivore then. Will be a lot easier. You have to give up the cake.

Re: Scientist busts myths about how humans burn calories

#572

Post by wildmanx »

Irony.

A linked article describing a scientist trying to rigorously find out how weight changes and energy expenditure and diet are connected, revealing the little we do know and the vast sea of what we do not know.

The discussion here: full of anecdotes and bro science berating one another "that's not how it works, it works like this", "I personally do this-and-that", "you just have to x-y-z, it's that simple".

Re: Scientist busts myths about how humans burn calories

#573

Post by dan00 »

rob74 wrote: post #407
artdigital wrote: post #378

Earlier quoted context omitted.

My advise: (as someone who does a lot of working out and calorie control) Write down what you eat for a while and its calories. Weigh yourself daily as well and write that down too. If after a week your weight went up: Your calories are above your TDEE. If it went down: Your calories are under your TDEE. And that's basically it, once you know what your TDEE is, eat under it to create a caloric deficit and you will lo…

Of course, eating less is the ideal solution if you can muster the willpower to actually do it - but that's a big "if" for many people...

You might try an other diet that‘s more filling and creates less cravings. So less carbs and more protein and fat. I don‘t think that willpower really works in this regard long term. It only creates frustrations.

Re: Scientist busts myths about how humans burn calories

#574

Post by AnIdiotOnTheNet »

dTal wrote: post #454
namdnay wrote: post #416

Earlier quoted context omitted.

A single cinnamon roll is nearly 500 calories. As soon as you’re combining fat and sugar things skyrocket

I would not class eating TWO cinnamon buns back to back as a "snack", but rather "a disgusting pig-out". Am I sheltered?

Maybe you're just not in a location where that sort of eating is common. Like the American south or midwest.

Re: Scientist busts myths about how humans burn calories

#575

Post by scotty79 »

maxerickson wrote: post #557
scotty79 wrote: post #554

Earlier quoted context omitted.

Apparently 700kcal burned per hour of cycling is a pretty realistic number. https://www.welovecycling.com/wide/2020/05/14/how-to-convert... Also resting kcal burn might be around 1800 per day. So 40% increase in of calories burned by hour of cycling per day every day is achievable. The question is how can you breathe out additional ~10h of CO2 within an hour? 3 times deeper breathes 3 times faster? Because that carbo…

The CO2 concentration going up in the blood increases the efficiency of respiration (because it is ultimately diffusion). You don't necessarily need to exchange 10 times the volume of air to deal with the additional CO2.

Range given for concentration of CO2 on exhaled air is 4-5%

So it looks like it could be 25% difference at most.

Re: Scientist busts myths about how humans burn calories

#576

Post by projektfu »

Some of the papers have strange errors that suprise me that they passed peer review. For example, "Extreme events reveal an alimentary limit on sustained maximal human energy expenditure" by Thurber, others, and Pontzer has a figure labeled "Fig. 3 Maximal Energy Intake". First, it appears that one of the charts is labeled incorrectly. I assume it is the first one, and they swapped "Overfeeding" with "Endurance". Second, it seems that taking the disparate types of "event" and putting them together on the Energy Intake graph causes them to have a flat slope, whereas the slope would be somewhat positive for the subgroups.

This was like one of the first few things I looked at in this body of research, I wasn't combing through everything to find an error. But it's strange. Finding an error quickly is a red flag to me.

Overall the study I'm looking at is interesting. I'm not sure they adequately demonstrated the finding of a caloric intake limit of 2.5x BMR but there appears to be a definite negative correlation of duration of sustained activity and energy expenditure (or metabolic scope, a multiple of basal metabolic rate). The numbers are very tightly clustered around the trendline, which is kind of odd, given how widely the numbers vary in other graphs. So either this is a very close correlation or something is strange with the data.

Glancing through the papers in PubMed, I think that the implications in the article are way stronger than the papers support. One paper said that perhaps 25% of the calories expended in exercise are borrowed from a reduction in BMR. The article made it seem like they were completely offset. The article referenced above apparently used two very different groups (overfeeding and endurance competition), and used the first to study the limit of energy intake and the second to study the long-term limit of energy expenditure, but people are making claims about energy intake in endurance athletes. Maybe when you're working hard, the gut is able to adapt and pull in more calories. Perhaps there is a limit to how much the gut is willing to accept when there is a calorie surplus.

Maybe I'm way off base.

Re: Scientist busts myths about how humans burn calories

#577

Post by throwaway09223 »

nradov wrote: post #563
throwaway09223 wrote: post #206

Earlier quoted context omitted.

I'm a 40 year old guy who's been sitting behind a desk writing software for two decades. I was in good shape in my 20s but haven't exercised significantly in a very long time. It took me about three months to get up to that speed, cycling every other day. I started out doing 10 miles, at 10mph. Three months isn't all that long for an exercise program.

Color me skeptical. In order to burn 1000 kcal in 60 minutes a cyclist would have to sustain a power output of about 280 W. Do you have a calibrated power meter, or are you going by the "vanity" calories displayed by most stationary bikes? There are certainly plenty of trained cyclists who can maintain that power output, but I've never seen anyone reach that level after only 3 months. If you really did that then you'…

I don't know, actually. I'll check it out later today. I do know my heart rate is around 150-160 throughout.

I did a lot of cycling in my 20s and while I'm at least a decade out of shape I'm sure I'm relying a lot on past training.

Re: Scientist busts myths about how humans burn calories

#578

Post by balfirevic »

nkurz wrote: post #565
balfirevic wrote: post #552

Earlier quoted context omitted.

> A few hours on my bike can be 2,000-3,000 additional calories over base metabolic rate. Are you sure? 2000 kcal in 3 hours is 770 watts of power output. Edit: Wikipedia [0] says "During a bicycle race, an elite cyclist can produce close to 400 watts of mechanical power over an hour and in short bursts over double that - 1000 to 1100 watts; modern racing bicycles have greater than 95% mechanical efficiency. An adult…

You are forgetting that the human body is nowhere near 100% efficient at burning fuel to put power into a pedal. To produce 400 watts of mechanical power, the body consumes about 4 times that amount of fuel (25% efficiency). Consuming 2000 kcal over 3 hours is thus closer to the more realistic 200W of power to the pedals, and even the higher ranges make sense if he's a good athlete. See this article: https://www.welo…

> You are forgetting that the human body is nowhere near 100% efficient at burning fuel to put power into a pedal.

I'm not, because the parent poster explicitly said "That's not based on made-up calories but actual work from a power meter on the bike."

Which seems absurd, hence my comment.

Re: Scientist busts myths about how humans burn calories

#579

Post by kinghtown »

nradov wrote: post #189
kinghtown wrote: post #113

Earlier quoted context omitted.

I always feel there are some methodology issues in sports science studies like small sample sizes or strange metrics. While I do agree with you that sustained, high level activity requires and burns more calories, I think that the advice coming out of there, exercise is less efficient than diet for weight loss, is going to absolutely be true for the majority of gym goers who quite frankly are phoning it in whenever t…

For the majority of regular people feeling tired and worn out is more likely to be caused by lack of sleep and too much booze than by lack of food or excessive exercise.

I meant more from training hard for long term. Most people are not at this level or pushing that hard. Normal people would definitely benefit from lifestyle changes outside of the gym if they are tired and worn out.

Re: Scientist busts myths about how humans burn calories

#580

Post by confidantlake »

_9omd wrote: post #65
dahart wrote: post #4

> “You can’t exercise your way out of obesity,” […] “you can’t outrun a bad diet.” While this article is being a bit dramatic and possibly understating the impact of exercise slightly, I feel a little dumb that I didn’t know this earlier. It took me several decades too long to understand the obvious, that exercise is for building strength, and losing weight happens by eating less. I tried for way too many years to ex…

I think a big part of the issue is that popular fitness and weight loss advice has perpetuated the wrong way to exercise to loose weight. When most people think about exercise for weight loss, they imagine long exhausting sessions on the treadmill, dripping with sweat, and a high calorie burn number. While the short term results may seem great based on the immediate calories burned, it's actually a terrible strategy…

Meh idk. Look at any long distance runners. They are skinny. Based on my own ancedotal evidence when I am running often I tend to be 20lbs less than when I don't.
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