Cost per mile

CiB

It's not 11p a mile, otherwise my commute would cost me £4.64 a day and would hardly be worth doing. In simple terms the cost is whatever we might eat on top of a normal daily diet to cycle in, compared with days when we drive. I take the same packed lunch whatever method I use to get in - a couple of sandwiches, a yoghurt and a bit of fruit, so in my world cycling is free in terms of additonal costs. You could factor in the occasional packet of Lidl's finest choccy biscuits at 59p a packet if you want but dividing that into my 84 commuting miles a week isn't close to 11p a mile.

Point is that you can work it out however it suits you best, but applying a fixed 11p per mile or whatever as a static one-size-fits-all isn't valid.

<smiley...>

meanredspider

Yes - this only works for individuals. It's a bit like comparing the running costs of two different cars.

I happen to spend around £3 a day on extra food on the days I cycle - and I do 30 miles a day so that nearly matches the 11p per mile. I could get the extra I needed much cheaper though. Or far more expensively too.

wyadvd

CiB wrote:

It's not 11p a mile, otherwise my commute would cost me £4.64 a day and would hardly be worth doing. In simple terms the cost is whatever we might eat on top of a normal daily diet to cycle in, compared with days when we drive. I take the same packed lunch whatever method I use to get in - a couple of sandwiches, a yoghurt and a bit of fruit, so in my world cycling is free in terms of additonal costs. You could factor in the occasional packet of Lidl's finest choccy biscuits at 59p a packet if you want but dividing that into my 84 commuting miles a week isn't close to 11p a mile.

Point is that you can work it out however it suits you best, but applying a fixed 11p per mile or whatever as a static one-size-fits-all isn't valid.

<smiley...>

You are not approaching the calculation in anything like a logical scientific way. The human body will even out your food intake over a number of months or even years by using fat and glycogen to store excess energy consumed. That's why you rarely eat that much more on the particular days when you cycle.

It is a totally inescapable fact that cycling at a reasonable speed (on the flat) uses a pretty consistent 50 calories per mile. This is a given and does not vary much for a given speed.

Then you have to look at the calorific value of your ENTIRE diet per week. You need to look at the cost of your entire diet for the week and divide the cost by the calories. This will give you a figure of around 0.2p per calorie maybe a little more. I contend that this figure will also be pretty consistent.

To arrive at a cost per mile multiply 50 by£0 .002
This will come to around 11p.
I'm right sorry

meanredspider

wyadvd wrote:

Then you have to look at the calorific value of your ENTIRE diet per week.

I don't understand this bit of logic. I need to divide the cost of the incremental food I eat. For instance, if I have a recovery shake on a cycling day and I don't on a non-cycling day, that is incremental. I understand that it needs to be carefully balanced but, assuming I do that, I can be reasonably sure of the additional cost.

wyadvd

meanredspider wrote:

wyadvd wrote:

Then you have to look at the calorific value of your ENTIRE diet per week.

I don't understand this bit of logic. I need to divide the cost of the incremental food I eat. For instance, if I have a recovery shake on a cycling day and I don't on a non-cycling day, that is incremental. I understand that it needs to be carefully balanced but, assuming I do that, I can be reasonably sure of the additional cost.

The incremental part of the calculation is the 50 calories per mile. Your cycling calories come from your entire diet, including fat from food you ate several months ago etc etc , not just the food that you have mentally labelled as 'cycling food' or even the food you eat as a result of hunger from cycling. That is usually retrospective after all. I've just done the exmoor beast and afterwards I went into tesco in Taunton ( another 24 mile ride from minehead) and bought approx 2500 calories in the form of 5 egg and bacon sandwiches at half price. I actually ate them at the checkout before I had thechnically paid for them. But those particular calories did not fuel my sportive, the calories I used for my sportive probably were eaten over the preceding week at least.

So if we accept the 50 cal per mile figure, then we have to calculate the average cost of a calorie in our chosen diet. If you put the average per capita spend on 2200 calories nationally you get a value of just one .2 p per calorie. You have to use an average figure because the human body is very good at evening out energy use age and consumption over several weeks using glycogen and fat.
A pilchard sandwich is a great recovery meal btw!

meanredspider

I don't agree with your approach. Sure, the calories I burn could have come from anywhere but the calories I take on to specifically "replace" them come from a specific place. My diet on cycling days and non- cycling days is quite different. I eat more calorie-dense food. Also, I tend to eat food only I eat rather than the other meals I share with my family - again, costs are different. The calories I get from a plate of pasta with the family are much cheaper than the calories from a Starbucks muffin on a cycling day.

I don't think your number is necessarily a million miles out (because it uses averages) but the real numbers for individuals could be twice or half that.

daviesee

wyadvd wrote:

...................
To arrive at a cost per mile multiply 50 by£0 .002
This will come to around 11p.
I'm right sorry

At best this is assuming a constant weight.
There are a lot of people who look on cycling as a fun way to lose weight, well me anyway .
Taking on extra calories when cycling would counter act this.
I eat nothing extra when I cycle so my extra cost is £0.00.

unclejimbo1983

meanredspider wrote:

I don't agree with your approach. Sure, the calories I burn could have come from anywhere but the calories I take on to specifically "replace" them come from a specific place. My diet on cycling days and non- cycling days is quite different. I eat more calorie-dense food. Also, I tend to eat food only I eat rather than the other meals I share with my family - again, costs are different. The calories I get from a plate of pasta with the family are much cheaper than the calories from a Starbucks muffin on a cycling day.

I don't think your number is necessarily a million miles out (because it uses averages) but the real numbers for individuals could be twice or half that.

I was just about to (perhaps inadvisedly) weigh in with a similar point.

I watched a video on this very website a couple of months ago in which Graeme Obree (no less!) advocated a jam sandwich as a recovery meal. Now, one jam sandwich might not cover the full calorie cost, but bread is really cheap. I reckon I could eat an entire loaf of bread every day and the increase in food cost would equate to less than 8p a mile.

Obviously if you substituted your whole diet for jam sandwiches you'd die of scurvy, but if you leave in the meal pattern of a "normal" person and add some cheap calorific crap, I'd wager you can add the extra calories quite cheaply without any nasty health consequences.

Of course, if you are averse to cheap processed calories then your food cost will be higher, but that's more of a "nice food" cost than a cycling cost IMO.

wyadvd

meanredspider wrote:

I don't agree with your approach. Sure, the calories I burn could have come from anywhere but the calories I take on to specifically "replace" them come from a specific place. My diet on cycling days and non- cycling days is quite different. I eat more calorie-dense food. Also, I tend to eat food only I eat rather than the other meals I share with my family - again, costs are different. The calories I get from a plate of pasta with the family are much cheaper than the calories from a Starbucks muffin on a cycling day.

I don't think your number is necessarily a million miles out (because it uses averages) but the real numbers for individuals could be twice or half that.

God this is a geeky conversation, but that's the sort I love. Firstly I think for a figure like this we have to work with averages. Calorie rich food (ie fatty and complex carbs) will take getting on for 24 hrs to enter the blood in a metabolisable form. So eating that on the same day as cycling is not necessarily going to result in those calories being used for cycling. It is very difficult to track the food we eat through our bodies. This would require radioactive isotope tracking of food and nuclear medicine imaging to show where the actual meals we eat end up in our bodies. Very difficult to do. We just have to know what an average calorie costs and multiply it by our calorie per mile figure.

The other confounding factor is that fact that Some people run very 'hand to mouth' with the food in v energy out equation. Other people don't feel the need to eat that much more when they cycle because they are better at buffering that food-energy thing. But the thing is they are still using the same energy per mile and the food they use probably costs about the same, but when they stop cycling they continue to eat about the same and store the excess. these are the people who complain that cycling isnt costingthem extra in food but it is really.

Graeme Obree is a hero of mine. He advocates marmalade sandwiches as an energy source while riding and pilchards on toast for recovery! But he's also a bit of a nutter (like me)

meanredspider

I don't think tht you can average this - that's where we differ.

For me, it's much more simple. What would a week cost me when I cycle and what would a week cost me if I don't.

If I'm fuelled on Starbucks muffins, the 50kcals cost 30p. If I'm fuelled on pasta or porridge it's about 2p. When I'm cycling, I'm far more likely to be eating the extra calories in the former than the latter. If I'm not cycling, I steer clear of the expensive calories. A can of "energy" drink at £1 is a similar cost to the muffin for calories. If you were to use energy gels, they're even more expensive.

CanalRider

When I started cycling to work three years ago I sold my 4x4. So I am already saving £240/month on fuel, £35/month insurance, £18/month VEL, plus servicing etc.
I don't eat bigger meals so food cost is unchanged and I have spent about £2400 on bike stuff (2x bikes, garmin, clothes, tyres and lights)
Motoring has cost me about 3000 per annum, cycling 2500 over 3 years.

To stop my smugness the wife has a Lexus.

wyadvd

CanalRider wrote:

When I started cycling to work three years ago I sold my 4x4. So I am already saving £240/month on fuel, £35/month insurance, £18/month VEL, plus servicing etc.
I don't eat bigger meals so food cost is unchanged and I have spent about £2400 on bike stuff (2x bikes, garmin, clothes, tyres and lights)
Motoring has cost me about 3000 per annum, cycling 2500 over 3 years.

To stop my smugness the wife has a Lexus.

You lost about 7 kg in weight over 10 months. That's about £100 worth of food by my calculation. (That you paid for before you started cycling). Enough for about 1000 miles.

wyadvd

meanredspider wrote:

I don't think tht you can average this - that's where we differ.

For me, it's much more simple. What would a week cost me when I cycle and what would a week cost me if I don't.

If I'm fuelled on Starbucks muffins, the 50kcals cost 30p. If I'm fuelled on pasta or porridge it's about 2p. When I'm cycling, I'm far more likely to be eating the extra calories in the former than the latter. If I'm not cycling, I steer clear of the expensive calories. A can of "energy" drink at £1 is a similar cost to the muffin for calories. If you were to use energy gels, they're even more expensive.

It's the meal you eat at home the previous day that is giving you about half the calories for your commute, plus the other half coming from fat reserves laid down over many months or years . The Starbucks lunch will most likely end up in the fat reserves to be burnt another week. That's how the body works. I'll ask my consultant cardiologist colleague tomorrow and see if he agrees with me if you like.

wyadvd

I have found this piece of peer reviewed research from Australia which comes up with the same ball park figure as me at 5.4 Australian cents per km for food costs. It should answer everyone's questions and lead to the cessation of this thread:

http://grapevine.net.au/~mccluskeyarund ... ycling.pdf

meanredspider

wyadvd wrote:

It's the meal you eat at home the previous day that is giving you about half the calories for your commute, plus the other half coming from fat reserves laid down over many months or years . The Starbucks lunch will most likely end up in the fat reserves to be burnt another week. That's how the body works. I'll ask my consultant cardiologist colleague tomorrow and see if he agrees with me if you like.

No need - I work in R&D for a diabetes company. Where the calories you burn come from depends on a wide range of things - not least of all the duration and intensity of your exercise - but plenty of it comes directly from what you eat on that day. If it didn't, energy gels & drinks would be useless when, in fact, they are available to your body to use within minutes rather than hours. But the whole system is very complex - far far more complex than I think you understand.

But you are still missing my point - I don't really understand why. The cost of cycling is the cost of the EXTRA food I NEED to eat because I cycle. I eat quite differently if I'm cycling or not cycling - THAT''S the incremental cost of cycling. Whether that precise calorie is used by my muscles to push the pedal around or by my brain to think about work is irrelevant - if I wasn't cycling, I wouldn't have eaten it.

meanredspider

wyadvd wrote:

I have found this piece of peer reviewed research from Australia which comes up with the same ball park figure as me at 5.4 Australian cents per km for food costs. It should answer everyone's questions and lead to the cessation of this thread:

http://grapevine.net.au/~mccluskeyarund ... ycling.pdf

Well I make that about half your number

5.4 x 0.6 x 1.6 = 5.2p

But that's a number for the average cyclist riding an average bike at an average pace for an average distance eating average food at an average cost and doing average maintenance using average parts etc etc Even someone of average intelligence can see that it's, at best, an average quality answer. How many people on here do you think are average cyclists?

wyadvd

meanredspider wrote:

wyadvd wrote:

It's the meal you eat at home the previous day that is giving you about half the calories for your commute, plus the other half coming from fat reserves laid down over many months or years . The Starbucks lunch will most likely end up in the fat reserves to be burnt another week. That's how the body works. I'll ask my consultant cardiologist colleague tomorrow and see if he agrees with me if you like.

No need - I work in R&D for a diabetes company. Where the calories you burn come from depends on a wide range of things - not least of all the duration and intensity of your exercise - but plenty of it comes directly from what you eat on that day. If it didn't, energy gels & drinks would be useless when, in fact, they are available to your body to use within minutes rather than hours. But the whole system is very complex - far far more complex than I think you understand.

But you are still missing my point - I don't really understand why. The cost of cycling is the cost of the EXTRA food I NEED to eat because I cycle. I eat quite differently if I'm cycling or not cycling - THAT''S the incremental cost of cycling. Whether that precise calorie is used by my muscles to push the pedal around or by my brain to think about work is irrelevant - if I wasn't cycling, I wouldn't have eaten it.

Just because of the name of the thread that's all!
I do have some detailed understanding of how the body handles energy metabolism. And I know that around 60% of most cycling is fuelled by burning fat. That's the clincher for me. I am trying to quantify this thing so the geeks amount us have a figure for fuel costs to stick in their spread sheets. I believe it is pretty consistent and pretty quantifiable as long as you are happy to take an average cost of all the calories you eat and you accept that you burn 50 cals a mile.
I think most people grossly underestimate the fuel costs of running a bike for several reason: a) they think that just because they ate 3500 calories before they cycled and they still eat the same but lose weight,that somehow those cycling calories don't cost at the checkout. b) they are just so horrified to discover that the fuel costs of a bike are the same as a small car that they just cannot accept it. c) they have no real idea how many calories they consume over a reasonable period. Or what they really cost.

I do accept your point that cycling a lot produces a need to eat at or around that time. That is what I am like. My appetite changes very quickly in the weeks when I cycle. I am in the same boat as you because i spend a small fortune in the canteen and estimate my cycling energy cost at around 25p per mile as a result using my whole diet average. But some people are not like that, they eat on a level regardless of activity. Their hunger reflex is not attuned to their level of activity. These people say that cycling isn't costing them extra in food.

I am trying to get across the point that these people are in fact spending exactly the same amount of food on their cycling but paying for it financially earlier. It's these people I am trying to convince that they do have a cost to their fuel when they say it is non existent. The calories they burn still cost them money.

meanredspider

I agree broadly with your conclusions I just don't agree with your logic

wyadvd

meanredspider wrote:

I agree broadly with your conclusions I just don't agree with your logic

We shall spar another time no doubt!

jimmypippa

wyadvd wrote:

meanredspider wrote:

No need - I work in R&D for a diabetes company. Where the calories you burn come from depends on a wide range of things - not least of all the duration and intensity of your exercise - but plenty of it comes directly from what you eat on that day. If it didn't, energy gels & drinks would be useless when, in fact, they are available to your body to use within minutes rather than hours. But the whole system is very complex - far far more complex than I think you understand.

But you are still missing my point - I don't really understand why. The cost of cycling is the cost of the EXTRA food I NEED to eat because I cycle. I eat quite differently if I'm cycling or not cycling - THAT''S the incremental cost of cycling. Whether that precise calorie is used by my muscles to push the pedal around or by my brain to think about work is irrelevant - if I wasn't cycling, I wouldn't have eaten it.

Just because of the name of the thread that's all!
I do have some detailed understanding of how the body handles energy metabolism. And I know that around 60% of most cycling is fuelled by burning fat. That's the clincher for me. I am trying to quantify this thing so the geeks amount us have a figure for fuel costs to stick in their spread sheets. I believe it is pretty consistent and pretty quantifiable as long as you are happy to take an average cost of all the calories you eat and you accept that you burn 50 cals a mile.
I think most people grossly underestimate the fuel costs of running a bike for several reason: a) they think that just because they ate 3500 calories before they cycled and they still eat the same but lose weight,that somehow those cycling calories don't cost at the checkout. b) they are just so horrified to discover that the fuel costs of a bike are the same as a small car that they just cannot accept it. c) they have no real idea how many calories they consume over a reasonable period. Or what they really cost.

I do accept your point that cycling a lot produces a need to eat at or around that time. That is what I am like. My appetite changes very quickly in the weeks when I cycle. I am in the same boat as you because i spend a small fortune in the canteen and estimate my cycling energy cost at around 25p per mile as a result using my whole diet average. But some people are not like that, they eat on a level regardless of activity. Their hunger reflex is not attuned to their level of activity. These people say that cycling isn't costing them extra in food.

I am trying to get across the point that these people are in fact spending exactly the same amount of food on their cycling but paying for it financially earlier. It's these people I am trying to convince that they do have a cost to their fuel when they say it is non existent. The calories they burn still cost them money.

I can see your point in that the calories might still cost money, but the money has already been spent and would otherwise not be available for anything else. If someone kept cycling, the eventually there might need to be an increase in calorific intake to stabilise their weight but against that, the calories required to maintain a lower weight are less than to maintain a higher weight, and the calories per mile are less for a lighter person too (maybe only significant in someone like Gaz's case).


As an aside, I personally eat a lot more when I do cycle, usually fairly soon afterwards. Oddly enough I don't get too hungry on a full day's hillwalking/running at the time although afterwards is a different matter, but that is a slightly different level of activity. I know in that situation that I do have to force myself to eat.

roger_merriman

I eat a lot more if i've gone for a ride, either stopping for coffee/cake or a big lunch/supper but if i'm just riding for work I eat no more probably less since it's normally a training day so while might be coffee on tap getting food is less easy.

daviesee

wyadvd wrote:

The other confounding factor is that fact that Some people run very 'hand to mouth' with the food in v energy out equation. Other people don't feel the need to eat that much more when they cycle because they are better at buffering that food-energy thing. But the thing is they are still using the same energy per mile and the food they use probably costs about the same, but when they stop cycling they continue to eat about the same and store the excess. these are the people who complain that cycling isnt costingthem extra in food but it is really.

Trouble is that you are looking at this from a completely scientific point of view.
I don't live my life to those rules.
FWIW I ate more before I started cycling than I do now*, so that's that theory out the way.

*I was also much heavier. Without any statistical evidence, I would guess that the majority of the population of this Country eat what they want, when they want, regardless of the calories in/calories out balance.
As an example. Today was a really nice day, I went out on a 45 mile ride and never ate more than normal. Had it been a really bad day I would have watched a movie and it is highly likely that I would have eaten snack/goodies and therefore taken on more calories than normal. Conclusion - Cycling not only burnt calories but saved on intake as well.
No scientific formula or studies will change that. People are different and lead different lives.

CiB

I still won't have it, that fuel costs of 11p per mile are a valid figure based on some 'research' somewhere. So this 0.02p per calorie then? I make my own sandwiches so that cost is nowhere near the £2.50 or whatever it costs to buy one from the nearest Tesco Metro. We [tend to] eat mainly home cooked food like spag bol or meat + spuds + veg which also costs a sight less than buying a takeaway in or getting a couple of pizzas from the supermarket. So some arbitrary average that arrives at a figure of 0.02 per calorie is no more meaningful for me - and therefore for everyone else on here - than comparing my average speed on one of my 'normal' rides with yours. It's just a number that might be close for one or two people.

And it's still irrlevant anyway, as we're discussing additional costs for cycling and as already agreed most of what we need we've eaten anyway apparently. It may be that some of us overeat and were it not for cycling would be a bit more rotund than we 'd like, but the bottom line is that for a lot of us, the additional intake that we attribute to cycling is minimal. Whether that's true or not, it's indisputable that those of us who don't [dramatically] alter our intake aren't incurring any significant additional costs when cycling, and certainly not to the tune of 11p per mile. Argue till you're blue in the face but if we don't eat any significant amount of additional food when cycling 20, 30, 40 & more miles, cycling isn't costing an additional 11p per mile.

wyadvd

I spend 100 a week for a family of 3= 50000 calories that0.2 p per calories purchased. I cycle 150 miles a week so it's pretty reasonable to say that £16.50 of that 100 goes to fuel my bike. It's wrong headed to earmark particular meals for your cycling in my opinion, you have to use the cost of all the calories you buy in a week and divide that into the number of calories.

The other thing is that the Canadian tax authorities went away and did the same calculation and now allow cycle couriers there a £10 a day fuel allowance because the average cycle courier cycles 90 miles in Toronto apparently.
10/90=???
Have a look at this on YouTube:
http://youtu.be/R-WYFZs2_XQ

meanredspider

wyadvd wrote:

I spend 100 a week for a family of 3= 50000 calories that0.2 p per calories purchased. I cycle 150 miles a week so it's pretty reasonable to say that £16.50 of that 100 goes to fuel my bike. It's wrong headed to earmark particular meals for your cycling in my opinion, you have to use the cost of all the calories you buy in a week and divide that into the number of calories.

The other thing is that the Canadian tax authorities went away and did the same calculation and now allow cycle couriers there a £10 a day fuel allowance because the average cycle courier cycles 90 miles in Toronto apparently.
10/90=???
Have a look at this on YouTube:
http://youtu.be/R-WYFZs2_XQ

Let's try this a different way. If you broke a leg (let's hope not), would you eat as much? If you did a 100-mile sportive, would you eat the same?

I think your paradigm on this comes from the fact that you cycle daily and it's therefore difficult to separate what you eat from when you cycle. I don't cycle daily so I watch what I eat very carefully depending upon what riding I do in any particular week - the difference in a week that I cycle 5 days to a week to when I'm on a business trip (and don't cycle) is around 6000kcals - that's nearly half as much again as the week I don't cycle. I can then pretty accurately determine the difference in the food I eat.

wyadvd

Well I have been cycling 4 years now, and I know that I eat around 1500 calories per day more now than when I drove to work. When I did my sportive last weekend, I somehow managed to fit an extra two meals into that day plus the two bottles of squeezy honey I slurped along the way. I am pretty sure I ate a little more for several days afterwards too but that's difficult to quantify. Some of it came from my fridge, some from the Lorna doon B and B in minehead, and some from the canteen carriage on the train, some of it in the form of egg and bacon sandwiches from Taunton tesco metro (£1 a sarny 600 kcals a sarny). In the days following the beast, I think I took on about 4500 extra calories compared to normal. My strava account gives 50 kcals a mile for all my riding over the last 18 months so ill take that as pretty accurate. If I broke my leg I am pretty sure my intake would drop from around 4000 calories to 2500 or fewer calories per day over the course of a week or so. As I would not be burning 30*50 =1500 calories.
I don't accept that the calories I eat when I cycle are priced significantly more or less than my non cycling calories. If anything they are slightly more expensive, but not by much, as I raid the canteen at work. If I have no lunch at all at work, then I accept my wife's evening meal gladly but make a massive bowl of cous cous to have with it and eat about 6 weetabix before I go to bed. Sometimes I leave my wallet at home by mistake see.

bompington

wyadvd wrote:

I spend 100 a week for a family of 3

Well, for a start, I spend £90 a week for a family of 5. But the most serious mistake you're making is to assume that every calorie costs the same.
Your statement a while back (sorry if I'm quoting wrong, CBA to look) that "60% of most cycling energy comes from fat" kind of implies that 60% of the calories in your diet are fat, a quite dangerous figure if you actually managed it. (I just looked it up and "a well known cancer-fighting website" said that USDA guidelines, whatever they are, said up to 30% should come from fat).
Most of the energy in my diet comes from the cheaper bulk carbs - pasta, potatoes, rice. The things that cost more are the little luxuries that make it all more palatable. If I need to eat more, I eat more of the bulk things - and very little more of the luxuries.

meanredspider

@Wyadvd Great - so you have a better handle on my type of eating - some days I need to eat about 1200 calories (half as much again) more than other days. Those 1200kcals I attribute directly to cycling. It's very easy for me know precisely what the differences are. It would be much easier to eat a steady amount - unfortunately it's more complicated for me than that. If I cycled steadily, then I'd tend to agree with you that it makes no difference where the calories come from.

wyadvd

meanredspider wrote:

@Wyadvd Great - so you have a better handle on my type of eating - some days I need to eat about 1200 calories (half as much again) more than other days. Those 1200kcals I attribute directly to cycling. It's very easy for me know precisely what the differences are. It would be much easier to eat a steady amount - unfortunately it's more complicated for me than that. If I cycled steadily, then I'd tend to agree with you that it makes no difference where the calories come from.

You are a pretty good case study then! You and me have appetites that adjust quickly to the demands on our bodies. Some people don't work that way even if they stop and start cycling. They are the ones that argue that cycling costs them nothing. In a way they are right. But that is to undervalue their spare tyre. Spare tyres are worth real money to cyclists you know! I don't have the benefit of one , I just have a measly six pack poor me.

wyadvd

bompington wrote:

wyadvd wrote:

I spend 100 a week for a family of 3

Well, for a start, I spend £90 a week for a family of 5. But the most serious mistake you're making is to assume that every calorie costs the same.
Your statement a while back (sorry if I'm quoting wrong, CBA to look) that "60% of most cycling energy comes from fat" kind of implies that 60% of the calories in your diet are fat, a quite dangerous figure if you actually managed it. (I just looked it up and "a well known cancer-fighting website" said that USDA guidelines, whatever they are, said up to 30% should come from fat).
Most of the energy in my diet comes from the cheaper bulk carbs - pasta, potatoes, rice. The things that cost more are the little luxuries that make it all more palatable. If I need to eat more, I eat more of the bulk things - and very little more of the luxuries.

I include in that an allowance for my canteen spend at work. Of £20 per week for for 10000 calories=0.2p per calorie