Only three things in this world are certain: death, taxes, and fad diets.

Fad diets, borne of sometimes questionable science, have a way of blossoming online and amassing adherents (and pageviews) despite their troubled history. They promise quick and easy results as long as their followers stick to some strict guidelines — which usually prescribe entirely excluding or only consuming certain types of food. In other words, they don’t exactly advocate for the balanced meals and healthy lifestyle choices that are routinely endorsed by, oh, the CDC, WHO, NHS, and most every other reputable source.

These fad diets may even deliver for a while (after all, short term results look good for those “before” and “after” photos.) The problem is, pounds easily shed are just as easily regained, and the effects on the dieter’s health are unpredictable at best. Some of the more mercenary fad diets go so far as to push herbal supplements, whose safety and efficacy are unregulated and dubious.

No matter how many of these miracle menus come and go, we never seem to learn this lesson: They don’t usually work. But we seem to need to believe in the silver bullet solution — the list of rules and the slick mnemonics that promise a slimmer waistline. It eluded us before, but that’s no matter — this new fad diet will work. Tomorrow we will eat only poultry, eat only cheese, eat only foods that begin with the letter “G”. And, so we eat on, bellies against the current, borne back ceaselessly into the flab.

Two diets that have received a fair amount of attention — the Paleo and the Nordic Diets — point in different directions for a healthy lifestyle, and we examine their relative virtues and drawbacks below.

The Paleo Diet (as in paleolithic) is as succinct as it is retro: If a caveman didn’t eat it, you can’t eat it. Paleo dieting is based on the idea that the evolution of human beings basically stopped shortly before we began domesticating animals and practicing agriculture. Our metabolisms evolved to perfectly match the realities of the hunter-gatherer lifestyle and haven’t caught up to any of the advances we’ve made in food production since. Everything from peanuts to peanut M&Ms is off limits, and that includes grains, breads, rice, potatoes, beans, and all dairy products. Paleo dieters stick to fruits, vegetables, grass-fed meat, fish, and nuts.

Now, if you truly wish to do as the Stone Agers did out of some misplaced sense of nostalgia, consider that their life expectancy was considerably shorter than ours; that it’s virtually impossible to know, let alone recreate, exactly what was on our ancestors’ plates; and that our bodies are more adaptable than the paleo pitchers would have you believe. To its credit, the paleo diet does push an exercise plan in line with the caveman lifestyle — in essence, less pilates and more pretending that you’re running from a saber-toothed tiger. Old school.

The Nordic Diet, or more accurately perhaps the New Nordic Diet, recommends foods in line with the traditional and locally available staples of the Nordic countries, and emphasizes the values of freshness, seasonality, and sustainability. The NND has its roots in a 2004 conference in Copenhagen where food professionals from the Nordic countries met to define a regional cuisine that was both healthy and traditional. The diet was codified in a manifesto by chef Claus Meyer and popularized via the trend of Nordic-inspired upscale restaurants that take locavore eating to new levels (including Meyer’s Noma, voted the world’s greatest restaurant four of the last five years).

Despite the high pedigree (and costs) of New Nordic restaurants, the diet itself is pretty straightforward. It values local, organic produce, such as fruit, berries, and root vegetables; whole grains; and responsibly caught fish rich in omega-3 fatty acids. The NND sensibly shuns processed foods, advises rapeseed (canola) oil over olive oil, and recommends low-temperature cooking methods to preserve the foods’ nutritional value.

In efficacy, intelligence, and — from our point of view — taste, the Nordic Diet is the clear winner here. It doesn’t have the popularity or the dramatic flair of the Paleo Diet. What it does have is balance, variety, the imprimatur of health professionals, and the enthusiasm of the worlds’ most celebrated chefs. And while the Paleo Diet takes its cues from a distant past, the New Nordic Cuisine looks forward toward a future that is viable, sustainable, and healthy.

Photo: Lynn Gardner via Flickr