The skinny on which trendy diet is best.

America must be getting thinner, right? McDonald's has stopped super-sizing. Coke has launched its "half the sugar, half the carbs" C2 cola, and it seems like every week a new diet book hits the shelves and the best-seller lists.

I myself have been a fat skinny-guy since I started drinking beer at age 14. Imagine Chris Farley's belly on Mick Jagger's frame. That's me. I've tried running, a daily sit-up routine, yoga, swimming. Once I even tried to stop drinking. That lasted an afternoon. Lately I've been watching Nip/Tuck and fantasizing about getting my gut sucked out with a tube. Then I thought about the cost (about $3,000) and the bruises. Eventually, I came to accept that I would always have my new friends, the gut and love handles. Maybe we could start a band together.

After a friend told me he lost 15 pounds on a low-carb fad diet, I decided to head to my local Borders bookstore to see if there was a diet book right for me. When I discovered an entire section dedicated to diet books, I was immediately overwhelmed. What's the difference between Atkins and The Zone? Dr. Phil is loud, mean, and kind of chubby himself—why should I listen to his dietary recommendations? Does the Maker's Diet involve drinking large quantities of Maker's Mark? Isn't alcohol what got me bloated in the first place? What's a fat skinny-guy to do?

Admittedly, it was the "Lose Belly Fat First!" emblazoned inside a gold circle on the cover of The South Beach Diet that won me over.

At a recent summer barbecue, reluctantly rejecting beer, potato salad, and the most succulent watermelon I have ever seen, I told friends I was starting Day 1 of the South Beach Diet (for a story I was writing for Slate, I made sure to disclaim), a regimen that begins with a two-week induction period in which sugars, carbohydrates, higher-fat meats, and alcohol are to be avoided like anthrax. My friends looked at me with a combination of disbelief and disdain. I was, after all, a seemingly skinny guy. Then I slowly lifted my T-shirt and introduced them to my inner Michelin Man. After they stopped laughing, my friends agreed maybe the South Beach Diet wasn't such a bad idea.

I cheated a little during the induction phase, mostly on the alcohol ban (I had a wedding to attend, four cross-country flights to endure, and two air-guitar competitions to compete in—as if I could avoid all alcohol under such circumstances!). I also sometimes ate "American" bacon instead of Canadian bacon—let's just call that patriotism. Despite my occasional straying from the South Beach dogma, I did manage to lose about seven pounds. By Day 4, my gut really did feel different. It was smaller and less blubbery. I think I actually detected muscle under there for the first time in almost 15 years.

Giddy with my success in completing Phase 1, I decided to return to my normal eating and drinking routine (usually a mixture of gourmet foods and lowbrow junk) and celebrated with three slices of pizza and an ice-cold Coca-Cola (regular, not C2). To my surprise, sugary things tasted too sweet and I began to stare at high-carb foods with confusion and distrust, like a dog tilts its head after being yelled at for peeing on the divan. Bread now seems like a bizarre thing with which to begin a meal. I've been drinking vodka (among the lowest in carbs of all alcohols) mixed with soda (no sugar) instead of beer, and I still feel pretty good. I've only gained back a pound or two.

Though I chose to do South Beach, I was still curious: What really makes one diet different from the next and how does the average, uninformed person like me know which book in the heap to reach for? I decided to compare some of the books in a highly unscientific study to find out how each of them "weighs in," in terms of crucial factors—like, what celebrities are doing it? What delectable foods are off-limits? And, most important, how easy is the diet?

The results:

Dr. Atkins New Diet Revolution, by Robert C. Atkins, M.D., $14.95 (paperback)