This summer saw the comic book character the Incredible Hulk turned into a so-so movie. It strikes me that the beloved gamma-irradiated behemoth combines two common but false fears about biology: (1) that radiation causes completely unpredictable, bizarre transformations and (2) that extra body mass can somehow materialize without any extra mass being consumed by the body.
The first fear is more familiar, a staple of monster movies since shortly after the first atomic bomb blast in 1945. The second is more an implicit fear that shows in some of the strange, counterintuitive things people say about dieting. More on that later.
Radiation can cause cancer or other mutations by breaking DNA strands in a fashion something like tossing pebbles through an elaborate and delicate wind chime. It is rare that the resulting change is a valuable new biological function and highly unlikely that even a valuable change will be one involving complex, systemic alterations. You might lose your hair, but you're unlikely to develop a working third lung or bullet-resistant skin and super-strength just as the wind chime may lose some of its capacity to make tinkly sounds but isn't likely to be pebbled into becoming a player piano.
But radiation is one of many things in life that seem mysterious and full of possibilities when you don't know the first thing about them, so it's a better dramatic device for turning Dr. Bruce Banner into the Hulk than, say, fire or steam.
Similarly, given radiation's potential to cause harm in certain circumstances and certain amounts, it's not hard to frighten people into thinking that any food that has been irradiated may well have cancer-causing or other mutagenic powers. Thus the current resistance in some quarters to food irradiation, despite the fact that the process does not leave food radioactive or cause dangerous chemical changes in it but does do a fantastic job of killing microorganisms, which are known causes of disease and sometimes death. Irradiated meat is not itself radioactive and will not render you radioactive any more than microwaved meat will, but it will help prevent some of the 5,000 deaths per year in the U.S. caused by food poisoning. (See ACSH's booklet on Irradiated Foods for more information.) Radiation's rep as a monster-maker turns a valuable disease-fighting tool into a tough sell in some quarters, unfortunately.
If you really want to instantaneously turn an ordinary man into a half-ton monster, though, you have a trickier problem to overcome than rewriting his genetic code: you either need to find him very rapidly or pull hundreds of pounds of mass out of thin air. It's a basic rule of physics that mass cannot be created or destroyed, only converted into other forms so presumably Banner absorbed an awful lot of energy from the "gamma bomb" that went off before his first transformation, but it's still hard to see where his extra mass comes from during subsequent transformations. In the comic books, as noted in the invaluable Handbook of the Marvel Universe (which should be on any responsible scientist's shelf), they eventually got around this problem in a clever albeit rococo fashion, by claiming that when Banner transforms into the Hulk, he actually borrows mass from a tiny alternate universe. This is not what scientists call an elegant solution, but at least they admitted they had some explaining to do. (I've elsewhere declared 2003 the "Year of the Nerd" because of all its sci-fi and superhero movie releases, so this is as good a time as any to analyze the Hulk.)
Oddly enough, Sandy Szwarc, in a series of articles about obesity for TechCentralStation.com, almost seems to embrace the genetic transformation/alternate universe theory of weight gain, marshaling some vague statistics to argue that Americans are neither eating more nor exercising less yet are mysteriously ballooning to historic proportions. She mocks those including me who suggest that the basic conservation of matter and energy implies that if you eat less and exercise more, you must lose weight and that conversely, if you are gaining weight, you must be taking in more calories or burning off fewer. (The first part of her series, in which she notes my half-serious argument that obesity is evil, can be found here, and, by the way, TCS who we like have also just posted ACSH's Dr. Elizabeth Whelan on another food topic, "trans fats" and earlier ran a piece on obesity by ACSH's Dr. Ruth Kava.)
Szwarc argues that dieting itself in what must be the greatest health irony since death by leeches is the cause of the obesity epidemic, that dieting alters the way in which our bodies' most basic genetic coding is metabolically interpreted, making fast metabolisms into slow ones and pound-shedding people into pound-retaining people. All the dieting that we as a culture have done in recent decades is the cause of our obesity, not the other way around.
It's an interesting theory, but Szwarc doesn't provide enough evidence from convincing sources to show that the data backs up the theory only that it can be coherently stated and has a certain ironic charm, which for many readers may make it intuitively powerful. But even if future research shows that dieting sends the body into a fat-retaining emergency mode, there really isn't any getting away from the conservation of energy or the first law of thermodynamics: keep decreasing the amount you eat, keep exercising more and eventually, you have to lose weight (and if Americans are getting heavier, those extra calories have to be coming from somewhere regardless of our metabolic rates). Trust me on this. And I wish it were otherwise. I'm not fat, nor a big snacker, but believe me, the idea of eating several lasagnas a day and claiming that no change in my routine could possibly reduce my resultant girth has a certain decadent appeal: "Mustn't diet! Could get fatter! Munch, munch!"
But then, I'd also like to be able to grab helicopters out of mid-air, repel bullets, and throw tanks over the horizon, and it's not going to happen. So: "Todd eat small meal now, remain puny human!! Urrrrh!"