Machka 

Weight is not that important.
Gender is not that important.
Age is not that important.
Speed is incorporated into the formula.
Climbing is not that important (what goes up must come down).


Yes, there is a difference between the two rides.
Yes, you burn 33 cal/mile.

If you cover the 30 miles at 16 mph, that means you were out there for 1 hour and 52 minutes. It took you 1 hour and 52 minutes, to burn 990 calories.

If you covered the 30 miles at 10 mph, that means you were out there for 3 hours. It took you 3 hours to burn 990 calories. In this case, if you decided to call it a day at 1 hour and 52 min ... you'd only have burned approx. 650 calories in 1 hour and 52 minutes, instead of 990 calories.

wphamilton

It's an approximate rule of thumb, which is what I think he's looking for in the question. It works better at low speeds (particularly running speeds) and flat. Higher speeds will take more than the 33 calories per mile (power goes up with speed cubed) and climbing is added on top of it (which is why I brought up m*g*h). Coming down after a climb will be at the higher speeds where wind resistance predominates, requiring more power over the ride, which means more calories burned. Or perhaps you're coasting down using no power on that portion and it all depends on what you burned going up. It's all approximate.

Don't hold my breath in other words.

Machka 

Yes, unless you're hooked up to a power metre (and I'm not even positive about those things ... I don't know) ... it's all approximate.

The 100 cal/5 km thing is a quick and easy calculation a person can do while riding. And we've discovered it's reasonably close to what Rowan's strava says. So we go with it.

FrenchFit 

Give it some time. Especially after a life time of ingesting lots of carbs daily it may take months/years to re-regulate. Switching to fat burning vs. carb/sugar burning takes time and I suspect your body is still hording fat. Yes, no doubt there is a drop off in immediate energy. I recall days I went to the gym and felt so lethargic I left after 10 minutes. The pay off in the long run [pun -- endurance efforts], is totally worth it.

bruce19

Thanks. This is pretty much what is happening to me.

bruce19

I think this is what has been confusing me. What you are using is an estimate based on your experience. Nothing wrong with that. But, when you called it a "formula" I was looking for an actual formula. And, since over the years I've spent some time researching how to estimate calorie burn, and all of the results include things like gender, age, weight, speed, etc. I couldn't understand how you got to where you got to. Much clearer now. Thanks.

DrIsotope

My issue is, if I went by the 33kcal/mi thing, for it to jive with my PM data I'd have to be over 35% efficient. This morning was 2,692kj for 51.6 miles, ~52.2kj/mi-- and that was my usual mixed-Z2 intensity. I average much closer to 50kcal/mi (from ~4 months of PM use,) which implies that by rule of thumb, I'm using 50% more energy than the average person? I don't buy it.

As has been said a zillion times, without a PM, we're all just guessing.

wolfchild

I put your formula 100 cal/5km to the test today...I went for a 5 km ride to do some errands and according to my bike computer I burned 65 calories on a 5km ride...There are a lot of variables, I rode slow and easy but if I went hard and fast I could of easily burned around 150++ calories in those 5 km.

sprince

The amount of energy used by a person on a given climb is dependent on their efficiency on the bike, the weather, the weight of the bike, the clothing worn, and it goes on and on. Two people of identical weight, build, body fat, and fitness level could use vastly different amounts of energy to complete the same climb in the same time. Even a power meter can only provide part of the picture. As to weight loss, it adds another dimension with more variables that have to be factored into the calculations. So you might find that the variation for all humans is within a certain range for metabolic efficiency, but chain that in series with another variable and the end result could be exponentially different from a one dimensional formula.

wphamilton

Nope. The additional amount due to the climb (as we specified) does not depend on any of those factors, other than weight (the "m") and their efficiency (the metabolic efficiency). There will be zero difference in additional energy due to those factors.

But thanks for the explanation of what you were thinking.

McBTC

How about the speed in moving the weight and... a headwind?

Sixty Fiver

If you are among those of us who have adopted or are adopting a lower carb regimen it does take some time for the body to switch gears and for some it requires some calorie restriction and for others it is just a matter of reducing carbs.

My wife lost a considerable amount of weight by reducing her carbs intake but not reducing her total caloric intake and her energy levels are pretty much through the roof. She has also maintained the weight loss and her physicals show some remarkably good numbers.

I keep my carb intake below 100 grams per day and this keeps me lean and my weight stable... and my endurance and energy on the bike is excellent.

Protein should be matched to maintain your lean muscle weight; excess protein will convert to glucose and bump your blood sugars and this is where a lot of folks have problems, not understanding the process that is gluconeogenesis.

wphamilton

Those would be the portion without (or disregarding) the climb, the 33 calories per mile estimate for example. The energy added by the climb is m*g*h. This sort of thing tends to get over-thought. You can just add energies, as long as you keep them straight.

Here's how I see it. Gravity is a "conservative force" meaning it takes the same energy from point A to point B no matter how you get there. Up and down a hill, or around it, the same energy. But we all know that it's harder going up the hill, and that we burn more energy - just look at a bunch of strava rides rides if you don't believe it. Looking at it logically and extracting the different parts may seem like simplifying, but it's just getting down to what's really happening.

Unless it's really steep you're probably pedaling down anyway, using that estimated 33 cal per mile but just going faster. You're using that "flat ride" estimate going up as well. But you are also lifting that weight a certain distance, in addition to riding around. That part is easy compared to everything else: it's just weight times height times gravity. Just add it in.

Wind resistance, speed, what bike you're own, all of that is where the estimate per mile will break down or at least need to be modified individually. But it doesn't much pertain to lifting the weight up the hill.

Seattle Forrest

A flappy vest isn't going to slow you down much on the way up the mountain. Aerodynamics are an important factor at high speed but not as much at low speeds. And anyway air resistance makes you work more for the same speed, which a power meter will capture.

Seattle Forrest

That may be close to true on pavement. Dirt takes a lot more energy.

I've never been very comfortable with rules of thumb and formulas. I prefer to just measure. Even if my measurement is imperfect (like all measurements are), I feel more confident in a reliable, consistent method of evaluating the work I've done.

FBinNY 

That may be true for you because you and Rowan are fairly consistent in riding speed and conditions. However conditions will make a difference, and you'd burn more on rough roads than smooth. You also don't factor headwind, and lets face it, 10 miles into a headwind is burns more than the same 10 miles with a tailwind.

Lastly, the work done (fuel burned) isn't linear with speed. Drag is proportional to the square of wind speed (or ground speed in still air), so riding the same distance at twice the speed would mean you're working against 4 times the drag and would be working 4 times harder.

This square of the speed is why motorists are encouraged to drive slower to save fuel, and likewise cyclists riding slower would also save.

But, as I posted earlier, all this pointalism can hide the big picture. It isn't how many calories you eat or burn TODAY, it's the cumulative effect of your net calories in vs. out over time that counts. All this data may provide some guidance, but it doesn't have to be precise to do so. The acid test is net gain or loss of weight over time, and based on that you can make adjustments to the big picture stuff, then check progress next week to see if you're still on track.

Carbonfiberboy 

Listen to your advisers here. Pick the smallest calculated burn and go with it. Stop wishing you were burning more. There's no point to it. Go for the results you want, which is going to involve going calorie negative, like it or not. The scale tells the truth. If your calorie numbers are correct, the scale number goes down. If they are not, your scale will tell you.

If you want to get your burn up, work on getting the Strava average watts up. I have a SS with date, distance, and average watts. Obviously with increasing distance, average watts go down, but getting them up over the same distance is a good sign. PRs are a good sign. I like to see at least one PR on every ride if I'm actually training and not just piddling on the bike.

FBinNY 

It is and it isn't. On a flat ride at relatively constant speed weight barely matters because you're working against the wind rather than gravity. However, when your climbing you're working against gravity and weight counts. At the same time wind counts less because most people climb at lower speed than they cruise on flat ground.

So, weight will matter to a greater or lesser degree depending on the specifics of speed and terrain.

But, I repeat (I promise for the last time) You're standing too close and focused on the small dots that make up the picture. Stand back and look at the big picture and you'll see that it's not about each ride or each meal. It's about the long term intake and output, and the trend, even if there are reversals along the way.

It's like climbing a long grade to a mountain pass. Though you're climbing and end up higher, it doesn't mean that there won't be downhills along the way.

bruce19

Just to clarify, I am not wishing I was burning more. What I have tried to convey is that although my activities have remained relatively the same and my calorie intake has dropped significantly, I have not lost weight. This is over a 6-8 week period. That's what I don't understand. In the past if I had done this I would have lost some weight.

The discussion of calories burned via cycling is interesting to me only because every website I've ever visited and every book I've ever read and every trainer I've ever spoken to says that calorie burn is affected by a variety of factors and isn't as simple as X number of calories per mile regardless of all the other factors.

FBinNY 

Yes, the websites and the information posted here agree that it isn't as simple as a straight line correlation of calories per mile. But that's still a useful benchmark for comparison for the same person doing similar rides in his area.

It's about as useful as the average time you allow for your commute, which can change due to weather, changes in traffic, time of day, or if there's a collision or road closure, and here in NYC whether the President is in town. But you still use the benchmark, because you can't go through lif with a calculator.

As for weight loss or lack thereof, there are various possibilities.

1- you're kidding yourself about how much you're eating.
2- you're trading fat for muscle (you'll know because you're pulling the belt smaller
3- you're holding more water during recovery
4- over time you're becoming a more efficient engine, so burn less fuel for the same speed and distance.

Though I understand that weight loss is your goal, that's only one indicator of what's going on in your body. A better one is measuring lean vs fat which can be done one of a few ways, or you can either be patient and give the current regimen time to work, or cut back another 5-10% on the input side, and/or increase speed and mileage a bit and give it more time.

BTW- a staggering amount of weight can be "hidden" in your legs. The lean muscle mass is dense, plus depending on how you ride the long bone mass can go up slightly. Combine that with the fact that you don't tend to see leg weight, and it's obvious that cycling can make you heavier than you look.

My advice, don't let the scale discourage you, keep it up and measure by how your clothes fit. If you feel stagnated, consult a nutritionist for help balancing the makeup and timing of your diet for more activity.

bruce19

First, thank you for putting the time and energy into considering my questions. I appreciate that.

1. I'm doing a daily compilation of what I eat and I know for sure that I'm eating significantly less than I had been.
2. I may be trading fat for muscle. I have assumed that at age 70 that would be unlikely but I don't know. My waist is now about 2" smaller. I can now fit into 34 jeans.
3. Have no idea.
4. At age 70 I'm just happy the engine still starts.

Carbonfiberboy 

Ah. Probably you're becoming a little more efficient as you lose fat and gain muscle and particularly, muscle tone and a more efficient pedaling ability. It's still CICO but you're having to adjust to more correct calorie measurements.

As I and @FBinNY say, measure more than your waist.

FBinNY 

So there it is. You're losing waist, if not weight, and unless the fat that used to be around your middle is now around your neck, you're trading waist fat for leg muscle.

BTW- after a while, your legs will have the muscle they need and plateau there, so your lost waist fat will show up on the scale. Until then let your belt be your guide.

McBTC

We may need a physics check. I believe it takes more energy to move a given object more quickly. Lance Armstrong had to calculate how much energy it would take to raise his body and bike weight to the to finish line at Alp D'Huez but he also had to include how much more energy it would take to be at that line sooner than Jan Ullrich.

Seattle Forrest

I said this earlier in the thread and sprince kind of freaked out, but this bears repeating. It's not (fully explained by) #2. And I mean no offense to Bruce when I say this. As a rule:

If your efforts at weight loss have stalled, "you've accidentally built several pounds of muscle" is never the reason why.

Why?People say it a lot, maybe you're hitting a plateau because you're building muscle, at exactly the same rate as you expect to burn fat. It's a very common myth.

A DEXA scan will reveal all, and is relatively cheap. There's a place nearby that does 3 of them over an 18 month period for $300. I've been making a concerted effort to gain weight (build muscle) for months and I'm considering this.