Robot dogs and cloning are not the only developments anticipated in "Sleeper" that have come to pass. Near the beginning of Woody's Allen's 1973 science-fiction comedy, a doctor remarks that steak, cream pies, and deep-fried foods once "were thought to be unhealthy -- precisely the opposite of what we now know to be true." We seem to hear similar news every month or so.
 
Our latest "Sleeper" moment came when researchers announced that drinkers are less prone to obesity than teetotalers. The idea that one holiday indulgence could help protect us from the consequences of another has understandable appeal this time of year. But the hope that the things we like are also good for us springs eternal in a society where many people are irrationally anxious about pursuing pleasure for its own sake.

 How else are we to understand the reaction to a 2003 study that suggested eating dark chocolate can lower blood pressure? "You can sin with perhaps a little less bad feeling," one physician told the Associated Press, as if nibbling a Godiva truffle should be up there on the tablets with perjury, theft and murder.

 In the drinking study, published on Dec. 5 in BMC Public Health, two researchers analyzed data on 8,236 nonsmokers from the National Health and Nutrition Examination Survey, which includes direct measurement of body mass index (weight in kilograms divided by height in meters squared). Current drinkers were 27 percent less likely than abstainers to be obese, defined as having a BMI of 30 or more.

 That average conceals a more complicated picture: Although subjects who reported consumption of one or two drinks a day were substantially less likely to be obese than abstainers, those who said they had three drinks a day were about as likely to be obese, while those who said they had four or more drinks a day were substantially more likely to be obese. Since alcohol consumption was self-reported, the actual levels may be higher, but the trend of risk falling and then rising with the amount of drinking seems clear.

 As one skeptic pointed out in a Health Day story about the study, this association is counterintuitive, since "alcohol is very energy-dense," containing seven calories per gram, compared to nine for fat and four for protein and carbohydrates. Yet other studies, based on self-reported height and weight, have yielded similar results.

 Alcohol per se may not make people thin. But if people have after-dinner drinks instead of fat-rich desserts, the upshot might be lower calorie intake. Or it could simply be that the sort of people who consume alcohol moderately also tend to consume food moderately, unlike people who drink to excess or who abstain because they're afraid of losing control.

 Fortunately for those who need an excuse to have a drink, the beneficial health effects of alcohol consumption go beyond the association with lower weight. Many studies have found that moderate drinking reduces the risk of cardiovascular disease, for example, possibly through its impact on cholesterol.

 Although alcohol can be at least partly redeemed, it seems tobacco has been irrevocably condemned. Explaining the World Health Organization's new policy against hiring anyone who admits to using tobacco in any form, a WHO spokesman told The Associated Press: "With tobacco, there is no middle ground. It is black and white."

 From WHO's perspective, then, the occasional cigar is indistinguishable from a pack-a-day cigarette habit, even though the hazards are vastly different. When you combine this blind botanical prejudice with health-above-all puritanism, you get the self-righteous intolerance displayed by the typical anti-smoking activist.

 The rest of us are left to wonder whether everything we enjoy has to be good for us. Or could it be that we only enjoy what's bad for us? Then again, maybe our enjoyment is what makes it bad. Put that in your pipe, but for heaven's sake, don't smoke it.