Why trying to ‘burn off’ food is a waste of time
On 30 Dec I tweeted: “All these people ‘walking off’ indulgence make me laugh – I’d have to walk to Bristol & back (54 miles) to counter a Duchy Xmas pudding!” “Oh & that doesn’t deduct the BMR calories I would have used anyway so make that to Bath and back!”
Here’s the maths!
One fairly small (5 inch diameter) Duchy Original Christmas pudding contains 2,839 calories (313 per 100g)
We live 27 miles from Bristol. This site tells me that a 110lb person would use up 1,482 calories in 9 hours walking 27 miles at 3 miles per hour. Hence I have to walk there and back to ‘use up’ over 2,800 calories.
However – and this is something I only realised writing this blog that all calories burned calculators include the Basal Metabolic Rate. Hence, I would need to allow for what I would have been doing had I not been walking to Bristol and deduct this – because, by walking, I have only burned additional calories. If I had been writing for 9 hours instead, I would have used 808 calories, so, walking to Bristol would use 2,000 calories.
Just as well that none of this calorie stuff amounts to very much. If you want to be fit – be active; if you want to be slim – don’t eat Christmas Pudding!
16 thoughts on “Why trying to ‘burn off’ food is a waste of time”
Like your way of looking at things and seeking numerical truth vs. propaganda! For me, walking really does help shed fat pounds. Especially if I walk in a fasted (20 hours) state. I assume most of the carbs have passed by then and I am actually burning fat. The thing is that for this to be noticeable I will walk on average 4 hours per day. Not most folks are willing to do this. My assumption is that I’m burning around 300 kcals of fat per hour.
Additionally, when I’m getting fit I add HIT sprints a couple of times per week plus heavy lifting. I can almost feel the testosterone boost from Hit sprints! So yeah, one day of walking to some distant place may not help. But getting really fit does seem to work.
Keep on keeping them honest!
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A bit late in adding to the discussion, but I too believe that the correct amount of exercise is needed in tandem with a good diet (i.e. not fad diet, just healthy, know-what’s-good-for-you diet). I’ve always maintained a stable healthy weight all through my life and grew up on fresh food which has undoubtedly helped. But two years ago I broke my leg and after being immobilised for over 2 months, I started putting on weight, not a huge amount – 3-4 kg over my normal weight. But I also realised that at my age – then just turned 40 – it would prove a lot harder to lose than if I had been in my 20’s.
I started exercising and really got into my cycling and running but I noticed that my heart rate was too elevated when running and because of that I was exercising in the limits of aerobic exercise which meant that half of the fuel was taken from fat and the rest from muscles. So that didn’t help much with the flab… Lowering my heart rate meant that I was extracting most of the fuel from fat, for example when cycling so this kind of workout proved more beneficial in the end than the long, hard runs.
It does not follow from this that inactivity is not a factor in weight gain; weight gain, at least at first, is a much longer process than weightloss.
Consider this; the world’s highest obesity rates are in the small island nations of the South Pacific. Anthropologists characterise populations trapped on small islands, who make a living by fishing, as sedentary hunter gatherers. The addition of western foods to the diet of populations with pre-existing sedentary lifestyles has resulted in the highest obesity rates – ahead of those seen in islands with larger land areas.
So this sort of knowledge should not be used to argue from cure to causation, as some do, that reductions in activity cannot be behind the obesity epidemic. Convenience foods supply the wrong sorts of calories, AND they may be too convenient by half..
According to the website you mentioned, a person who weighs 100kg and runs 8km will burn 800 calories. You suggest that this figure includes the BMR and that we should subtract our BMR to get the real value of our exercise, i.e. the calories burnt above and beyond what we might have burnt if we’d sat on the couch instead.
That figure of 800 calories is in line with the accepted burn rate for running (or walking) on level ground of 1 calorie per km per kg of body weight. You should know that the formula calculates net energy expenditure, i.e. the extra energy needed for the exercise above BMR.
When testing energy expenditure in the lab, the resting rate (i.e. BMR) is subtracted to give the energy rating for a given exercise.
Ref: Essentials of Exercise Physiology. McArdle, Katch, Katch.
Hi Graham – I say that we need to deduct what we would have been doing otherwise – not BMR. I choose my words carefully.
Best wishes – Zoe
I jumped on the “chronic cardio” bandwagon and gained a TON of weight (25 pounds in 2 years). I stupidly believed that it was all muscle gain. After all, how could anyone accumulate fat eating 1500 calories of low calorie/high carb/low fat crap and running on a treadmill for 1 hour/day? (Please take note of the dripping sarcasm.) Plus, I was tired, sick, cranky and STARVING. Then, I got smart: stopped chronic cardio, resumed daily yoga, added a tiny bit of HIIT, and went low carb/high fat/high cal/real food. My BMI is 17 and I feel awesome and happy.
Ketosis is even better than you think: Unused blood sugar will eventually be converted to body fat, while ketones will be peed out. You’re literally “pissing away” unwanted calories!
Regarding exercise and weight loss:
Trying to “burning off” significant amounts of calories is an all but futile endeavour. Still, the fact that physical activity leads to weight loss is quite firmly established.
The most probable hypothesis I’ve stumbled across so far is that by being a layabout you’re signalling to your body: “All right, go ahead and fatten up – I don’t need to move anyway”. For the opposite effect, if you regularly move your body you’re signalling “I need to move to get things done, don’t hamper me by larding up too much”! [Source was a bit more detailed, arguing with evolutionary biology and stuff, but I can’t find it right now…]
I would like to defend exercise, even though research says it does not generally help with weight. It helps some people.
In week 24 of my “run 50 miles a week” diet I have lost 26 kilos. My weekly mileage has crept up to 60 miles, but I try to avoid binges. A few weeks in, I decided that I needed a backup plan in case I got injured, discovering low carb diets via Gary Taubes’ “Diet Delusion”. I have adjusted what I eat accordingly.
For me, exercise has a trigger effect: once I have started to lose weight I can stop denying that I am too fat, because I am doing something about it. This time, my attention is not on attaining a sensible weight (expected in April) but on sustaining the change in the way I live.
This is not for everybody. I happen to like running, and first got serious about it in 1973. It does improve the body’s capacity to burn fats and can help regulate mood. Last year, for the first time in my adult life I was not grumpy in November & December.
I am very glad to have found your blog. You are saying everything I have been saying for years, but largely shouted down by ignorant people. I am happy to see this post. I do actively discourage “exercise” defined as exercise you don’t want to do for whatever reason.
My point, forced exercise as motivation killer. When one embarks on a diet, one of the most important things is motivation. But the cost of unwanted exercise is imho high. Asking people to cut out food, some socialization, and then pile on unwanted exercise is a recipe for someone quitting that diet, very soon. I personally find that exercise makes me hungry.. so that is not helpful.
I am always hearing that exercise is will make me feel better and will help me lose weight, but most often, it doesn’t make me feel better, I generally end up hurting myself in some way, don’t have the time in the day for it, and usually show a gain on the scale due to water and muscle building (destroying my psyche). Of course I am active – I have an active job but, exercise, per se has to be evaluated on a person to person basis.
People should exercise to increase strength and coordination and to encourage heart and lung health, not to lose weight. Fat loss is at least 80 percent diet-driven (“diet” here being short for “dietary pattern,” not “low-calorie weight-loss regimen”).
Anyone who fails so much at logic that they interpret this article as a discouragement against exercise is someone who needs a lot more help than they can ever get from a blog.
I interpret it as yet another indictment of the mainstream interpretation of calorie theory.
You know, now that I look at my post – I feel I should clarify something…
I mentioned I don’t believe in calorie-deficit diets – what I should say is I don’t believe that simply cutting calories promotes weight loss. (Eliminating certain TYPES of calories sure helps, though…)
I also mentioned that I “burn off” food – when in reality I’ve been burning fat. The beauty of ketosis is using fat for fuel. If, through exercise and watching my intake I have a calorie-deficit of 2,000 calories, that energy comes from somewhere – in my case the very vast majority is fat. I’ve still got a little to lose (the last 20lbs is likely the most difficult) but I’ve come so far, and exercise has certainly helped.
I do believe weight-loss can be achieved by diet – I just believe that in the vast-majority of us, if we can add some vigorous exercise in – we’ll certainly accelerate it.
And Zoe – thanks for all your work AND promoting the truth about diet – I wish more people that work in the field of Nutrition would get on the truth bandwagon. You wouldn’t BELIEVE the things a nutritionist told me to eat after I was diagnosed with Type II diabetes. Wow.
Your article is excellent and thank you for your gems of wisdom! I’ve always been a fairly slim person and belived that you need to exercise to keep weight off. Before the Harcome Diet (by the way, I lost 7kg without a bit of additional exercise – now 54kg), I had tried keeping my calorie count under 1200 calories, but working in an office, I came to realise I could have my 7 sugary biscuits and cappacino each day and still keep well under 1200 calories. Needless to say, my “muffin top” waist still stayed with me. My 7kg weight loss absolutely defies the calorie counting propaganda – no exercise whatsoever and I was able to eat well over 1200 calories in generous sized portions at each meal when I felt like it. Steak, pork (with the fat!), cheese and full fat yoghurt, brown ricem oats…. lots of veggies! I’ve never eaten so well in my life! THANK YOU!!!! Your resesrch is appreciated, the results are proof. My mum-in-law has lost 6kg and my dad-in-law, 10kg thanks to the Harcomebe lifestyle.
Ashlee, Brisbane, Australia
Hi Ashlee – thank you SO much for sharing this – keep up the great work and the family too!
Very best wishes – Zoe
Also of note, being in Canada I’ve never heard of a Duchy Christmas Pudding so I looked it up on the internet.
It looks really good. You Brit’s have some great desserts. I shouldn’t have looked.
I’m concerned somewhat that this type of post encourages people to NOT exercise. I know that’s not your intent, but the title reads that way.
Personally, I “burn off” food all the time, and attribute it to my weight-loss success.
I lost over 80lbs in only a few months by eating LCHF and bike riding. There were many days I’d eat as little as 3,200 calories daily, and as much as 4,000 even 5,000 calories to help fuel my cycling. Those were days where I was cycling, at speed, through the mountains here in Alberta, Canada.
One Saturday I rode 110km through the mountains in about 4hrs. At the time I weighed 230lbs. That was over 5,000 calories burned in 4hrs. Yet my BMR at that weight (if resting 24hrs) would be only about 2,600 (about 217/hr). If four hours including BMR burned 5,000 calories, and the other 20 hours burned 2167 if I did nothing… that’s a total of 7,167 calories expended that day. Or a net caloric deficit of a MINIMUM of 2,167 calories.
Even on days where I rode only 1 hr, at my performance level it works out to over 1,250 calories. In an hour. On those days I typically ate about 3,200 calories. On such a day I’d have a deficit of over 500 calories if the other 23hrs were on bed-rest, which I assure you they weren’t. Basically, with a BMR that accounts for 217 per hour, 1,250 calories per hour of vigorous cycling is nothing to scoff at. That’s an additional 1,000+ calories in an hour.
Don’t get me wrong – I don’t subscribe to the theory of calorie-deficit weight-loss nor do I believe the first law of thermodynamics wholly applies to the human physiology. I do believe one shouldn’t eat too much though, even if LCHF, though.
I believe nutrition is 90% of the solution. I believe we must eat ENOUGH to fuel our lives – too often calorie-restrictive diets put people into such a deficit they don’t have the energy to lose weight, but at the same time, weight-loss can be accelerated with vigorous exercise. (
That being said – I wholly believe that for weight-loss, vigorous exercise is vastly superior to easy or moderate exercise. To explain this – lets say I walked easily for 4 hours as opposed to cycling vigorously 4 hrs, I’d have burned 3,000 calories LESS.
Or, if we use 1hr of exercise as our example: One hour of easy walking burns 261 vs 1,252 for cycling… that means an hour of easy walking is a net deficit of only 34 calories at my size, vs. 1,035 deficit from vigorous cycling.
I lost weight much faster once I could exercise vigorously. That’s been MY experience, others may differ. The truth is we are all different, and some don’t even have the ability to exercise much – I know I didn’t when I was nearly 320 lbs.
However, had I not started, I’d not be fit enough TO burn off the calories I do. It took 7 months of steady workouts starting at a whopping 10 minutes a day (that was all I could do when I started) before I could ride steadily at 28 or 29km/h. I tend to average about 26km/h in the mountains… the uphill part kills us big guys.
I hope I’m not out of line in mentioning this – but I truly believe exercise is a vital part of the weight-loss formula. Too many people are looking for some “magic pill” or “miracle diet” where they can lose-weight easily. Losing weight is healthy, but being fit adds so much more to the quality of one’s life.