Minimum Pricing of Discretionary Calories as a Potential Government Intervention.

As a general rule, I think it's safe to assume that cheap energy foods are driving the obesity epidemic.
I'm talking about sugar in drinks and lollies, flour in pasta and noodles and bread (one only has to include potatoes, normally a respectable enough vegetable, after deep frying and other extreme processing) and cheap oils. And the mixture of all 3 in biscuits, pastries, cakes, and "treats".

These are the foods the consumption of which has increased during the obesity epidemic. WHO reports that consumption of animal fats has decreased, but total fat consumption has increased. Where intake of calories has increased, these are the foods supplying the extra.

To give only one example, this paper (Behavioral risk factors for obesity during health transition in Vanuatu, South Pacific) found that

"Both the nutrient content and the preparation methods of tinned fish likely contribute to its association with obesity. Tinned fish canned in oil or sauce has higher fat content than most types of fresh fish (21). Furthermore, based on our observations, tinned fish and meat are often served with instant noodles and rice, whereas fresh fish and meat more often accompany dishes made with traditional root crops and vegetables, which are less calorie-dense by comparison. A heavy reliance on tinned fish in urban areas was noted during the first known nutrition survey conducted in Vanuatu in 1951 (22), and has been observed in many areas of the Pacific (23–25).

Our findings are similar to those of the Vanuatu Ministry of Health 1998 NCD survey, which highlighted associations among obesity and daily consumption of nontraditional fat sources (OR=2.19), including oil, margarine/butter, milk, fresh meat, poultry, tinned meat, and tinned fish (11). However, our analyses suggest that tinned fish might contribute more to the risk of nontraditional fats compared to fresh meat (including poultry). In fact, including fresh meat in the nontraditional fats category might actually weaken the observed association, since this emerged as a protective factor in linear regression models, perhaps because fresh meat displaces other less healthy options in the diet."

Tinned fish eaten in the Pacific is canned in soy oil. This, as well as the fact of it being eaten with instant noodles or rice, cancels out the antiobesigenic effects of fish oil omega 3 fatty acids (and, indeed, of protein) in the manner described in this review (Of Mice and Men; Factors abrogating the antiobesity effect of Omega-3 fatty acids).

In the USA, consumption of omega 3 has remained low, but that of omega 6 has climbed

Now it may be that butter is fattening, but this does not mean that it drives obesity (to do this a food has to not only supply energy, it also has to promote fat storage and overeating; there are particular hormonal pathways for this and every fat or carbohydrate or combination of the two doesn't influence these pathways to the same extent or even in the same direction - see the Of Mice and Men paper again - here is where a calorie is not a calorie). But let's assume, for avoiding arguments' sake, evidence to the contrary notwithstanding, that butter and soy oil are equally fattening at 9 calories per gram.
500 grams of butter, in New Zealand costs $4-5.
At $8.49 for 2 litres, soy oil is half that price per calorie.
Extra virgin olive oil, which everyone thinks is healthy, is $11.99 a litre, only a little more expensive than butter. Still cheap for 9,000 calories.
The idea of a minimum price, rather than a tax, is twofold; people might choose to use less fat because the cheapest fats would cost more. But the fats that are nutritious (butter is an important source of fat-soluble vitamins) or healthful (olive oil is thought to contain beneficial antioxidants) would not be affected, if their price were to be used as the benchmark for a minimum price for all fats.

How would this apply to sugars?
White sugar costs $1.91 for 500g (it gets complicated here because sugar becomes much cheaper in bulk, more nutritious sweeteners not so much.
Honey (the cheap clover variety) costs $5.19 for 500g. If that's too high a price for sugar, let's look at the least refined form of sugar - treacle. At $6.75 per Kg (price from cache), more than sugar (especially bulk sugar) but still cheap for 4,000 calories.

(Note: I am using prices from the Countdown website because they are available and internally consistent. I shop at Pak'nSave in Auckland so I'm used to prices being a bit lower. The examples I've used here are just that - examples).

From here on in, it's a job for experts. Foods have different prices per calorie at different sizes. It's relatively easy doing this with pure fats and sugars, it will be harder for me to calculate, say, for noodles vs potatoes without knowing the carbohydrate %. (I'm not an economist, I'm not even a shop assistant.)
But here we have white bread - only $1.48 for 600g.
And here's wholemeal bread, at $3.99 for 750g, about twice the price. Not much of a comparison here as the wholemeal bread is likely more processed than the white bread (read the label people, apparently it is no longer possible to bake bread without adding soy protein and a bunch of other non-traditional additives), but still, Government think it's healthier, and maybe it still is, and Government will be the ones responsible for administering any antiobesity food pricing system or tax.
And I'd rather they altered the food environment by pricing up the cheap, empty calories to be closer in price to the more nourishing ones, as opposed to taxing all fats (which would increase the cost of butter or olive oil more than that of soy or corn oil, because they cost more to start with), or taxing saturated fat, which would miss out gutter oils and cheap calories altogether. Similarly, taxing sugars would increase the price of honey or molasses more than that of white sugar or HFCS.

And yes, I know all the arguments as to why honey is so little different from sugar/HCFS as to make no difference. Those arguments apply if you think fructose is uniquely toxic, or if you're treating a condition for which carbohydrate needs to be restricted. But in the context of this discussion, how many people do you know who became obese eating honey without eating other junk carbohydrates? Honey has a flavour which tends to prevent it being overused in cooking in quite the same blithe way that sugar can be. And, low vitamin content and mere traces of minerals notwithstanding, it's a complete food for many of the bees in a hive. And it's well Paleo too, hunter-gatherers lap it up. Any regime of food pricing for health has to be about Lesser Evils, not Perfect Diets.

Based on these examples, we might come up with a minimum price of 0.1c per calorie (Kcal of course, food calories are always Kcal in physical terminology). This would give us a minimum price of $9.00 for a litre of soy or olive oil, $4.50 for 500g of butter, $4.00 for 1kg of sugar or honey. This conveniently rounded, decimal rate is almost perfect for these foods at present prices, and works across fat and sugar.

However, a Big Mac, at 492 calories, would have a minimum price of 49c. It has the more expensive protein in it, and the cost of extra labour and overheads, so it already costs more than that. Large fries would have about the same minimum price as a Big Mac, but are cheaper than Big Macs in reality (no meat, fries are just starch and oil). Processed fast food would need a higher rate, if you did want to target those calories. I'm not singling out McDonalds for effect; a KFC menu gives much the same result. But this does show targeting junk food won't catch the cheapest and emptiest calories, just some of the foods most likely to be addictive. And a change of price at the supermarket is a way of educating people about the quality of their food, which may carry over into the fast food environment. And far and away, calories consumed at home still outweigh those eaten at fast food joints.

So, back to the drawing board? I've taxed the limits of my rudimentary comprehension here. My brain hurts already. No more sums for me, but feel free to add your own.

Postscript; minimum pricing for one source of empty calories, alcohol, is already under investigation.

Much of the logic behind this initiative is similar to the the arguments I've raised.

 Let’s say the rate was set at $1.20. A 750 ml bottle of wine with 13 percent alcohol content has 7.7 standard drinks so could not be sold for less than $9.24. Not really much of a change there. However, a 3-litre cask of wine with 12.5 percent alcohol content contains 30 standard drinks so could not be sold for less than $36 – more than twice the current retail price.

And the drawbacks listed at the end of the article also apply to minimum pricing on food.

However, minimum pricing is not a magic bullet and is likely to have different effects on different populations. New Zealand is likely to be far more successful in reducing the use and misuse of alcohol across the spectrum if minimum pricing is introduced alongside a wider suite of policies.

For starters, without the recommended increase in the excise tax on alcohol or other similar measures, the additional revenue gathered under minimum pricing goes to the alcohol producers. In Canada, the state is the retailer, so this is not an issue. However, in New Zealand, this would be a lost opportunity for government, where even a small price increase is likely to result in significant additional revenue. That revenue would go a long way towards funding other harm-reduction activities, such as treatment, prevention or education. Perversely, if left in the coffers of the alcohol industry, it could be spent on measures designed to increase alcohol consumption (for example through increased expenditure on marketing).