Not only are the restrictions on soda and other sugars likely to be more effective as policy instruments, the sugar restrictions are probably more biologically significant than fat restrictions. Turns out the body does have a natural response to fat: cholecystokinin, which is secreted from the small intestine into the bloodstream and induces a sense of satiety in the brain, hence one reason the "olive oil" diet actually stands a chance. There may be others, like leptin, but we haven't fully elucidated those yet (my notes here.)

Sugars are a different story, in particular, fructose. There are a lot of different sugars, also known as carbohydrates. The basic sugar we and every other critter uses is glucose. Sucrose, table sugar (a disaccharide), is a molecule of glucose covalently bound to a molecule of fructose (two monosaccharides). The body does exactly one thing with sucrose: the enzymes of the small intestine split it into glucose and fructose before absorbing it into the blood. We also consume a lot of fructose straight up (high fructose corn syrup, anyone?). The body has no response to fructose except to burn it or turn it into fat.

There is no 'fructose' detector. There is a glucose detector: the beta-cell islets in the pancreas, which secrete insulin. To much blood sugar? Insulin goes up and the body 1) stores the excess fuel as fat, and 2) stops eating. Fructose can also be converted to fat, and, as we've seen, a lot of it is, but there's no signal to stop eating if what you're eating is fructose.

So: we have a mechanism to detect fat and stop eating. We have a mechanism to detect glucose and stop eating. We have no biological mechanism to monitor the level of fructose. Historically, fructose was not a major source of energy. Fruit was rare.

Now fructose comes in by freight train, in the same kind of rail car used to transport oil. Why? Because we grow a lot of corn and sugar beets, and we have powerful subsidies in effect to keep these crops in the ground, and lobbies that work to keep those subsidies in effect. They have a simple and powerful argument: the Dust Bowl. Of course there are other ways to keep roots in the ground, but that was the system we put in place 70 years ago, and we haven't dismantled it. Indeed, now we're trying to get even more money out of the subsidies by pushing anything that can be made from corn: beef, pork, poultry, biodiesel. (sidenote: diesel is diesel is carbon. The atmosphere doesn't care if the carbon came from corn or dinosaurs. At best you could argue that biodiesel is recycling, which is a far cry from reducing the carbon debt. But I digress.)

I don't see much of a downside to restrictions on sugary sodas or snack machines in schools.

The 2003 paper by Cutler, Glaeser and Shapiro, "Why Have Americans Become More Obese?", http://www.economics.harvard.edu/faculty/dcutler/papers/Why_Have_Americans_Become_More_Obese.pdf , is germaine to this discussion.

It makes two points. Firstly, increasing obesity can be correlated with increased calorie consumption, especially of snack foods. Secondly, food industrialisation means that high calorific-intensity foods such as fat, fructose and some proteins, especially chicken, have become progressively cheaper than complex carbohydrates, fruit and vegetables. Reduction is not just in purchase price but, equally importantly, in consumer preparation time. It is far quicker to buy a serve of fries than to buy a raw potato, take it home and cook it.

Absence of "full with fructose" bodily signal that Niels mentions didn't matter much once because most fruit and vegetables have low specific energy content. Stomach capacity limits the amount you can eat. (An apple is around 80 calories, 4 oz - think quarter-pounder - of sirloin beef is over 300, not to mention corn syrup in the bun).

As a check on this, how many obese vegetarians do you know?

Is one of the obesity issues a growing prevalence of adults who grew up in households where nobody knew how to cook nutritious meals using low priced ingredients?

_New Scientist_ reported a finding last week of evidence that obese people, "become as addicted to food in the same way that junkies do to their drugs... which may explain their constant cravings".

Scientists at Brookhaven National Laboratory in New York found in the case of seven obese people that the signal to their brain from their stomach, when it was full, actually went to the hippocampus. According to one of the scientists, this "is the area related to memory and the reward system. The areas lighting up were areas activated in drug addicts. It’s very similar to what triggers the craving for cocaine."

So, if for some people, food can be addictive, Becker's argument is persuasive: food best preferred by obese people should be taxed similarly to alcohol and tobacco.

The report is at http://www.newscientist.com/channel/health/dn10210-obese-may-be-food-junkies-with-constant-cravings.html

According to another report in the magazine this week, not surprisingly, MK-0557, a new appetite-suppressing drug, "has failed to deliver", http://www.newscientist.com/channel/health/mg19225723.200-obesity-linked-to-druglike-food-addiction.html

It's hard to come out on the side of cheap junk food but like any unhealthy habit which has a main benefit of pleasure it is possible to enjoy such things responsibly and many people do who do not need to be taxed.

In fact, I would think people are more capable of mitigating the unhealthy effects of junk food (for example, by changing their behavior and exercising a bit more than normal if they eat a candy bar) than they are able to manage the negative impact of things like cigarettes and alcohol.

It's also easier to detect (even by mere visual inspection) the "at-risk" users of junk food (in order to cut them off or tax those particular individuals instead of the population as a whole) than it is to detect the 3-pack-a-day smoker buying a carton at the 7/11 or the drunk driver getting a fifth at the liquor store.

It's much easier politically to blame inanimate objects and the large corporations that exploit our temptabilities instead of constituents and their weakness for sweets and lack of dietary and physical discipline.

And people seem not to perceive that sin taxes are any serious loss of liberty - as opposed to all-out bans of certain products, government weight-monitoring programs, or cumpulsory exercise would undoubtedly be perceived. It is also much cheaper logistically to create an easily administered universal excise tax than it is to focus on at-risk individuals and their consumption and exercise habits.

These political and logistic advantages are substantial and, even if minimally effective may still be more efficient than any feasible alternative. But I doubt fat taxes will do much at all for obesity levels, and I think policies that target such individuals with positive and negative incentives for the consequences of their behavior will be much more effective.

In the U.S. Army, (and this mostly applies to the unmarried junior enlisted) a certain amount of rigorous physical exercise is cumpulsory and reasonably healthy meals at dining facilities are subsidized at the rate of $9 a day. Nevertheless, soldiers can (and do) spend their own money on junk food, (and cigarettes, and alcohol, etc...). But they also know their athletic ability and fat index will be measured regularly with serious negative consequences (in addition to additional cumpulsory exercise and potential loss of priveleges to eat away from the DFAC) for a failure to stay in shape.

Of course such intense and effective targeting of indivuals in free society is impossible, but I would hope there would be some possibility of an incentive scheme indepedent of general taxation.

Your proposed restriction on selling soft drinks to children may lead to several difficult scenarios.
The sugar in soft drinks (unlike the alcohol or nicotine in other heavily regulated items) can be life saving to children who, because of diabetes or hypoglycemia, need to regulate their sugar levels. Thus, refusing to sell a soft drink to such a child could be a death sentence.
Furthermore, since the body expends its stores of glucose after rigorous exercise, athletes, both adult and child, often need to consume soft drinks or sports drink in order to replenish that supply.
If the legislator banned the sell of soft drinks to minors, but allowed sports drink to be sold, little good would be accomplished since there are nearly identical amounts of sugar in each and children would probably just switch from one to the other. If you were to ban both, then athletic children may become easily exhausted from their lack of glucose stores and therefore have to give up such activities; perhaps they may have to take up less exhaustive activities such as video games and watching television.
Finally, if one of your goals in banning the sell of soft drinks to minors is to grow productive members of society, will cutting off the children’s caffeine supply achieve that goal?

Since we are talking about efficient ways to reduce obesity, I think the first step, rather than taxing fat, would be to stop subsidizing corn. The heavy subsidies for corn [and they are ridiculous] contribute to the omnipresence of corn syrup as an ingredient in "junk food" by making it a really cheap ingredient. Rather than taxing unhealthy foods and subsidizing healthy ones, we are actually subsidizing the production and use of a pretty unhealthy ingredient. Cutting the subsidy [and refunding that money to taxpayers, or at least investing it in education or nutritional information] would remove a major market distortion and in so doing also make an unhealthy ingredient more expensive, lowering the demand for it. It would reduce the pleasure of those who enjoy corn syrup products, sure; but it would be fair because it would stop taxpayers from paying for others' pleasures.

It seems that children, like adults, need some kind of ‘feel-good’ substance in their diets or dealings. Sometimes this ‘feel-good’ substance has an element of self-abuse to it, which is why cranberry juice is an unpopular substitute for Sprite. Even if we allow children to consume only diet sodas, they would find some other unhealthy alternative.

More attention should be paid to the psychological aspects of obesity. It is not exclusive to the poor and to the extent that poverty breeds obesity, the emotional effects of paucity and insecurity may be to blame.

you mention junk food may be a gifffen good. perhaps it is an 'inferior' good like cigarettes: demand for it decreases as income increases. as people become richer, their incentive for healthy living increases, such as quitting smoking, eating healthy, reducing junk food consumption.

I have trouble with your assertion that a ban on soft drink sales to children would be easy to enforce. It seems to me that there are only two real options in enforcing this type of ban.

One approach is to tolerate a black market, and view the ban simply as a sort of revenueless Pigouvian tax that raises the (transaction) costs of obtaining the illegal good. This is the approach taken with respect to alcohol and tobacco sales to minors. In the US, specifically, the alcohol age is high enough that high school aged minors may not have many over-21s in their peer groups, but even in the US minors are able to obtain alcohol at some markup. Similarly, the enforcement of prohibition of very popular intoxicants such as alcohol and marijuana has often been abandoned in practice in favor of some sort of "hassle tax" approach.

The other approach is to be serious about the idea of an outright ban. This still does not imply that the ban is ineffective, but just that the authorities have not given up on it. The obvious example is the War on Drugs, which is still being fought vigorously by the federal government and the vast majority of state and local governments. This demands extreme amounts of law enforcement resources, and often leads to pressure on the courts (with which you are no doubt familiar) to limit civil liberties in order to facilitate the intrinsically difficult prosecution of crimes that lack a victim who can report them. As we all know, an unprecedented number of people have been locked up in the course of the war on drugs, and this has not resulted in significantly lower consumption rates than in more liberal regimes such as The Netherlands.

It is to be expected that in the event of a soft drink minimum age, most law enforcement utilities would opt for the hassle approach. I have trouble imagining wide-spread public support for a War on Soda. For one thing, there isn't a racial or cultural minority to scapegoat.

Now you may say that in effect, every ban does nothing but to raise the cost of obtaining the good, but still this would mean that law enforcement resources would be expended on raising a price that could be raised effectively, and with revenue, by means of taxation. I simply don't believe that a ban would lead to an efficient proportion of law enforcement effort to price increase.

I meant to say, of course, "law enforcement agencies", not "utilities."

Dear Judge Posner: I too am very skeptical about paternalism (whether in the form of a tax on fatty foods, restrictions on gambling, dress codes, drug laws, etc.), though I am less hostile towards 'educational campaigns', not because such campaigns are effective, but only because they at least have the virtue of being less obtrusive and less paternalistic than taxes and outright bans.

Also, I wanted to bring to your attention Adam Smith's ingenious argument against high tariffs on imported wine. In essence, Smith argued that when wine was cheap and easily available, people actually drank less than when it was taxed heavily and difficult to procure. If this is correct (and perhaps Smith got this one wrong), then it is not at all obvious that a tax on fatty foods (which people crave) would necessarily reduce consumption.

You mention the social stigma against being fat as providing some incentive for people to control their weight. I wonder if we could measure this effect now and how it might have changed over time? I would expect that it grows weaker over time as obesity becomes more prevalent, resulting in a sort of postive feedback loop that encourages further obesity. Furthermore, I would suspect that once an individual considers him or herself to be obese the effect of the stigma may also be reduced (i.e. by thoughts such as "well I'm already fat so what is another candy bar...") The latter point, if true, does raise greater concerns about obese children and that their condition might stay with them throughout their lives.

Finally, regarding video games and their role in this discussion, I think the not-to-distant future might witness the introduction of video games that require more physical activity. These could actually be a useful tool in the attempt to control obesity in children.

I'm afraid I have to disagree with the Becker-Posner point of view with regards to a fat tax. I disagree on the following grounds:

Both point out that excercise (or lack thereof) is a major contributor to obesity, not just unhealthy food. While that is true, I would think it would be much more difficult (as is pretty obvious since government has been trying for decades unsuccesfully) to try and reduce people's weight by helping them realize the importance of excercise. To me, it seems it would be easier to try to (dis)incentivize not eating the fatty food - if for no other reason than I think it would be harder to get people who aren't inclined to exercise to take a half-hour out of their day to exert high-level physical activity (which they obviously abhor anyway otherwise they wouldn't be obese).

I also would tend to doubt the possibility that whatever fatty or unhealthy foods are taxed are giffen goods. I would think this to be true simply because I don't believe that fatty foods or unhealthy foods are all that cheaper than foods that are good for you. While on the other hand they most certainly taste better, I think there exists enough reasonable (fairly inexpensive)substitutes (albeit not perfect) to call into question the idea of fatty foods or high sugar foods as being giffen goods.

Finally, since I believe the higher cost of the "bad" food would induce a substitution to healthier goods, I think it's reasonable to assume that many (if not most) people that eat unhealthily would prefer NOT to - but just can't help themselves (as opposed to being a "rational addict" from Becker...). I have no empirical evidence to back that up - but it seems more likley to me. Of course, the implication here is that these eaters do NOT adequtaely weigh the costs to their future health with the "happiness" derived from eating "bad" food. Or rather more likely, they DO weigh it - they just end up breaking down in momentary lapses of rationality which they immediately regret after the fact.

My main point here is that I think it is a very large mistake to confuse pyschological rationality with economic rationality. I think it's extremely apparent that the two types of rationality can both coexist, but in cases like eating fatty food, they can also fight against one another such that a person that wants to be economically rational, can't be due to their own psychology.

Garth

Posner: "[T]he significance of an externality lies in its effect on behavior, and I am dubious that people would consume fewer calories if they had to pay all their own medical costs rather than being able to unload many of those costs on Medicaid, Medicare, or the healthy members of private insurance pools."

While Posner addresses that fat people are free-riders, he seems to think there is no rational reason to do anything about it. But he is overlooking that fat people have other roles in the economy other than consumption. Fat people receive all sorts of benefits from the government, like tuition aid. We could easily mandate exercise in secondary school and condition federal tuition aid for college on health. If you haven't the discipline to get in shape, there's no reason other taxpayers should pay for your education. We save you costs if you save us costs.

Posner, unlike Becker, seems to realize that banning sales to minors is in theory a reasonable solution, because the problem is that unsupervised teens are eating junk. That is, the fact some adult libertarian likes it is irrelevant; we're talking about immature kids. But the problem with Posner's solution is the problem with an 18 year old drinking age -- the high school seniors purchase it and throw a party to which the 14 year old freshmen are invited and everybody gets drunk. The problem isn't that kids are drinking soda -- it's that they aren't drinking and eating healthy foods and that they need not exercise at school. A broad tax on fatty and junk food that funds a subsidy for fruits and vegetables, or subsidizes start-up costs for grocery stores in impoverished neighborhoods, would respond to Posner's concerns. If adult smokers can stand outside in the rain to smoke, then adult libertarians who like to eat fatty foods (myself included) can just pay a slightly higher price for their pleasure.

I would rather directly pay more for eating a fatty meal that I enjoy than having money taken out of my paycheck so some fat free-rider can eat a fatty meal that I don't enjoy and then make me pay for his triple-bypass. The latter just makes me angry. Neither Becker nor Posner seems to recognize that the free-riding pleasure of these fat theives is outweighed by the anger of having one's taxpayer dollars wasted.

I often hear about taxes on “sins” (be it junk food, alcohol, tobacco etc.), but I hardly ever hear about tax relieves on “virtues”.

Rather than taxing junk food governments could reduce taxes on healthy food, make membership to sport clubs tax deductible, and subsidise organisations that promote healthy leaving.

So, by taxing junk food, perhaps the government is not trying to improve citizens’ health, but looking for a source of revenue.

What would be the impact of a more healthy population?

My guess is that a healthier population would require fewer medical treatments, but would also live longer. The cost for the health service probably would not change much because the savings due to fewer treatments would be offset by the cost of caring for a person for a longer period of time.

Does anyone have any data about this?

Poor people are fatter because they have more pertinent things to worry about than how to stay skinny.

I have a few comments in response to the posting by Bobby Leonhard regarding "dificult scenerios". I am a pediatrician, so I counsel patients on these issues on a daily basis. I will address each "scenerio" in order:

(1) Leonhard asserts that the sugar in soft drinks "can by life saving to children who...need to regulate their sugar levels". There are plenty of other products available that serve the same purpose, such as Skittles, M&Ms or simply a packet of sugar (such as are found on restaurant tables). There are also medical-grade 'glucose tabs' available for diabetics who need a quick source of sugar. Additionally, diabetics who are experiencing hypogylcemia should probably stay away from drinking fluids anyway because of the risk of aspirating the fluid.

(2)The second assertion is that "since the body expends its stores of glucose after rigorous exercise, athletes, both adult and child, often need to consume soft drinks or sports drink in order to replenish that supply." This is simply false. Our bodies do expend the immediately-available glucose after rigorous exercise, but this does not lead to hypoglycemia because we are able to very efficiently generate new glucose through a process called 'gluconeogenesis'. If you think about this in an evolutionary/teleological context, it makes quite a bit of sense, otherwise there would have been hunter/gatherers dropping dead all over the place from hypoglycemia.

(3) Finally, "if one of your goals in banning the sell of soft drinks to minors is to grow productive members of society, will cutting off the children’s caffeine supply achieve that goal?" Let's hope this question is meant in jest.

Dear Dr. Posner-

One topic that neither you nor Dr. Becker have touched upon is the possibility that that low-income individuals have different marginal rates of time preference than higher-income individuals. I am wondering whether there exists a correlation between quality of life and one's willingness to "borrow" against future health. It seems reasonable that a person with little to look forward to might discount the future more heavily than others and show less concern about maintaining good health.

I got kicked off YouTube over two months ago. The reason? Contributing to the success of their service. I uploaded a good number of videos to YouTube, almost none of which I owned the copyright to, all of which I got from other sources on the internet. My first video, the “banned” Xbox 360 ad, was for a time the second most watched video on YouTube, with close to two million viewings click to see banned video (PATNOX.COM)

Katherine overlooks that those in good health have more to look forward to because bad health affects mood.

DanC: W says that the government imposes on him a health care system that he does not like so he has the right to impose his views of good and bad on others.

That's a strange synthesis of a mischaracterization of two independent arguments I made.

True enough, imposing externalities on others, e.g., your kids, can be immoral ("Let's raid Johnny's college fund to pay for meth.") But my assertion that externalities should be internalized is not based on sectarian morality nor is sectarian morality the justification for limiting government action to efficient provision of public goods.

I never said "the government imposes on me" anything. "The government" to you is apparently a deity with its own freedom of action. In reality "the government" simply consists of the mass desires of the people limited by generally accepted considerations of fairness. My problem is not with some deity that you believe in called "the government" but with the other people in this society who are shifting their health care costs onto me. It is not a "government" imposition -- it's an imposition by fat people.

It is true that if "the government" had lesser power over health care or taxation, fat people wouldn't be able to shift their health care costs on to me. But it is also true that "the government" is currently constituted the way it is. Instead of denying reality, I am responding to it and articulating an argument for a change from the status quo that will improve my lot. If you had read my argument, you would see I am not arguing for bigger "government" in the least -- my proposal is at least offsetting.

I fail to see how protecting my bedroom safe from the theiving intent of the fat (a tyrannical majority if ever there were one) somehow conflicts with the notion that the state has a basic duty to protect its citizens, i.e., the Nightwatchman State. http://en.wikipedia.org/wiki/Night_watchman_state

I'll also note that "Libertarian Paternalism" -- apparently -- does exist, and that left-libertarianism is a coherent philosophy.

Libertarian Paternalism: http://uchicagolaw.typepad.com/faculty/2006/10/sunstein_podcas.html

Left-Libertarianism: http://en.wikipedia.org/wiki/Left-libertarianism

A book on left-libertarianism: http://www.amazon.com/Libertarianism-without-Inequality-Michael-Otsuka/dp/0199280185/sr=1-1/qid=1160972894/ref=sr_1_1/102-7693810-2105745?ie=UTF8&s=books

Apparently, you flunked Libertarianism 101.