DOCTORS REPORTED in the Annals of Internal Medicine last week that diets don't work.
It took God knows how many years of medical school to discern what I could have told them over a mocha Frappuccino, but there you have it.
Diets don't work.
Or, rather, none of the commercial diet programs can be shown to work because the people who sell them can't, or won't, provide any evidence of success.
Scientists would like to see carefully controlled studies that follow plan participants for a couple of years but, since the companies that back these plans are disinclined to cooperate, scientists are left to assume the worst.
If there were any proof that Jenny Craig or L.A. Weight Loss or Atkins worked over the long haul, you'd be seeing a blizzard of television commercials heralding such success.
Instead, you just see the fine print: "Individual results may vary."
The news that diets don't work was no news to the editors of Real Simple magazine who, in a moment of journalistic prescience, have as their February cover story, "The (no-diet) diet."
In the accompanying article, author Mary Duenwald noted that diets work only while you are on them and they are intrinsically so unpleasant or so restrictive that you don't stay on them.
The magazine repeated the familiar advice to eat sensibly from the various food groups, include lots of vegetables and only eat red meat, butter, sweets and the white carbs in limited amounts.
The mother of editor Kristin van Ogtrop is a registered dietitian and imbued her daughter with this kind of good sense.
"Healthy eating is not about weird fad diets. It is about variety and control," said van Ogtrop in a telephone interview from her New York office.
"When my mother works with clients, she works within the bounds of what a client likes to eat. If you love brownies, she will find a way for you to eat that brownie," she said.
But not a brownie as big as a floor tile.
"There are no good or bad foods, only bad portions," Madelyn Fernstrom, director of the Weight Management Center at the University of Pittsburgh told Real Simple.
The twin pillars of permanent weight loss, then, are portion control and exercise, and applying both of them over the long term.
There are probably a lot of reasons why Americans are so fat, but the top two might be super-sized meals and sedentary lifestyles.
You can have carbs as long as you don't insist on eating a hub- cap full of spaghetti, and as long as you get something that looks like exercise several times a week.
Even so, don't expect to lose half your body weight in three months.
"One measure of maturity is realizing that quick fixes tend not to work," said van Ogtrop, who learned this lesson from her mother, too.
"Fad diets are so extreme that it is nothing that you can stick with in the long term.
"Either you become phenomenally bored because your eating is so restricted or you feel phenomenally deprived," she said.
Advice about exercise is all over the map - from 30 minutes three times a week to one hour daily. What is certain is that you can't lose weight unless you exercise regularly.
It is part of the calories in/calories out equation, but there is more to it than that.
"Exercising is an investment," said van Ogtrop. "And once you've made that investment, you don't want to squander it on a half-dozen donuts."
Chris Crowley, co-author of Younger Next Year, speaking on NBC's Today show echoed this sentiment.
"Diets don't work, pills don't work, gadgets don't work. Exercise works," he said.
"Once you put in place the daily exercise, then the other daily choices follow much easier.
"It is much easier to pick up an apple instead of a bagel if you feel good about yourself," he said.
The average American weighs 24 pounds more than he or she did in 1960, according to Real Simple. For women that's the difference between 140 and 164 pounds.
The way to lose that 24 pounds is not, therefore, in New Year's resolutions or gym memberships or books or diet supplements or food coaches or meal replacements or infomercials.
Medical science is no doubt on the verge of confirming that the secret to permanent weight loss is in tennis shoes.