It turns out that there is good food for thought behind many so-called fad diets. In addition to this they are not as different as first appearances suggest.
A new paper reviewing various food philosophies from Paleo to Mediterranean, low-GI to vegetarian, says they essentially follow the same underlying principles.
"Claims for the established superiority of any one specific diet over others are exaggerated," say the paper's authors, Yale medical researchers David Katz and Samuel Meller. "The weight of evidence strongly supports a theme of healthful eating while allowing for variations on that theme.
"A diet of minimally processed foods close to nature, predominantly plants, is decisively associated with health promotion and disease prevention and is consistent with the salient components of seemingly distinct dietary approaches."
Dr Loren Cordain, author of The Paleo Diet, agrees.
"The message is stick to healthy foods and stay away from processed foods," says Cordain, a newly retired professor in the Department of Health and Exercise Science at Colorado State University. "Whether you want to call it Mediterranean, Japanese or Paleo, that should be the message."
It is on this basis that Cordain rejects Paleo's wooden spoon for being the worst of 32 diets according to a US News and World survey.
The diet, which advocates eating as our ancestors did pre-processed foods and pre-agriculture therefore avoiding dairy and wholegrains as well as sugar and refined foods, was criticised for being impractical.
"Duplicating such a regimen in modern times would be difficult," argue the experts in the panel of judges.
"To clarify, that isn't a science paper," counters Cordain, who was in Australia last week to speak at the BioCeuticals Research Symposium. "It's ill-informed and not based on data but opinion."
He believes that those who consider Paleo a poor diet choice do so based on multiple misconceptions.
"It's not saying let's all be hunter-gatherers in the 21st century," says Cordain, "but we can make intelligent food choices ... it's about 'let's start eating real, living, healthy foods' ...
"As soon as you say food groups are eliminated, there's a knee-jerk response that it's nutrient-deficient. Let's let science be the judge."
Based on the 13 vitamins and minerals most lacking in the US diet, Cordain argues that eliminating certain food groups in this instance, enriches rather than depletes the diet.
"Seventy per cent of calories in the US diet come from four food groups: refined sugars, refined grains, refined vegetable oils and refined dairy," he says. "By making the suggestion that we get those out of our diet [to improve our health], that's really the message."
Dietitians argue that dairy and wholegrains add nutrients to our diets, but Cordain believes they are more about comfort than benefit.
"If you want to eat them, fine, but you're better off eating a bowl of broccoli than a slice of bread," he says. "Humans don't have to eat wheat, but it's in our comfort foods ... your mum didn't bring you salmon at your birthday party when you were a kid."
Nutrient profile aside, it's a fair point and one that applies to many of us, who don't eat purely for fuel but also for pleasure.
Yet, somewhat surprisingly, Cordain says these ''comfort foods'' can still be a part of the Paleo diet or any other diet.
"If you want to have pizza and beer, you can," he says. "They're guidelines and you can comply with them any way you want. You just give people information and they make their own decision."
Certainly, there is an abundance of information out there and nutritional science is evolving at a rapid rate.
For instance, Cordain says: "When I wrote the book [in 2001], I was pretty much on board with the idea that saturated fat was not a good thing."
Since then, he has shifted his perspective based on the latest science and the book was updated in 2010 to reflect this.
But, with the shifting science and with the clutter of competing diet claims, it can become confusing.
Which it needn't be, argue the Yale paper authors. Diet affects both our vitality and our longevity, so it is a significant issue. But, it doesn't necessarily have to be a complex one.
For the plethora of diets and science out there, there is commonality among the claims, the authors say: Eat food, not too much, mostly plants.
