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Deep Dive into Diets, Part 1 – U.S. News Review
Nutrition-fitness guru Jason Boehm probes the popular guide from US News & World Report.

01/04/2017 Jason Boehm with Craig Weatherby

Nearly three in four adult Americans are overweight or obese.

So it’s unsurprising that many New Year resolutions include weight loss.

And Americans' weight problem explains why they spent some $60 billion on gyms, diet plans, and weight-loss supplements in 2011.

You’ve likely encountered someone who lost pounds — at least temporarily — with Paleo, Weight Watchers, Jenny Craig, Atkins, or another popular plan.

Sadly, as study after study has shown, it's usually much easier to lose weight than to keep it off, and few diets are backed by proof of long-term weight loss.

A testimonial from a friend (pardon the pun) carries weight ... but beware of testimonials offered by sellers of programs and supplements.

Also beware of before-and-after photos from sellers of weight loss supplements. Insiders say that the “after” photos often show models before they deliberately gained weight.

The U.S. News & World Report annual diet ranking
While no weight-loss diet works for everyone, some work better for most than others.

Cost and convenience make some diets more popular than others, regardless of average results.

Picking the best plan is a challenge, and for the past six years, U.S. News & World Report (USNWR) has ranked popular diets according their nutritional quality, health benefits, and ability to shed weight.

We zeroed in on the magazine's ranking of diets for their ability to help people lose weight.

(WebMD publishes a review that covers many more diets but does not rank them. And each diet is reviewed by a single expert, which may allow more room for bias.)

USNWR asked 20 experts to evaluate 38 popular diets for their "Best Diets 2017" review. Nearly all were registered dietitians, people with doctorate (Ph.D.) degrees in related fields, and/or medical doctors.

To ward off possible bias, each expert disclosed conflicts of interest, and panelists did not rate any diet affected by a conflict.

(Of course, if an evaluator wanted to boost the diet with which they were associated, they could simply down-rate a competitor!)

The experts evaluated all 38 diets on each of seven criteria:
1. Ease
2. Safety
3. Long-term weight loss
4. Short-term weight loss
5. Nutritional completeness
6. Potential for preventing and managing diabetes
7. Potential for preventing and managing heart disease

The magazine’s editors then converted those evaluations into star ratings, ranging from five (best) to one (worst).

They also divided the 38 diets into nine categories, such as Best for Diabetes, Best for Weight-Loss, Best for Fast Weight-Loss, and Easiest to Follow.

Unsurprisingly, most diets fell into several of the nine categories. Weight Watchers, for instance, tied for slot #4 in Best Diets Overall, and tied for #1 in Best for Weight Loss, Easiest to Follow, and Best Commercial Diet Plans.

Even though its rankings can be confusing, and reflect inevitable (often unconscious) biases and subective views, many news outlets accept the US News rankings as gospel.

“Not all diets are created equal, and no one knows that more than US News & World Report,” wrote Jessica Orwig in Business Outsider. And as Elizabeth Narins wrote in Cosmopolitan, “The whole thing is very mathematical and therefore, quite scientifically sound”.

We wish it were that simple!

Regardless, the USNWR rankings probably influence and shape how the general public perceives popular diets.

The top 5 (actually 9) weight-loss diets
These were the top 5 Weight Loss Diets, according to the USNWR panel.

Volumetrics and Jenny Craig tied for the #2 slot, so these four plans actually represent the top three weight-loss diets:

  • Weight Watchers: This commercial plan combines group or personal coaching with food rankings and recipes, and is backed by substantial research, some funded by the company.
  • Volumetrics: This diet was pioneered by Penn State nutrition professor Barbara Rolls. Her book teaches how to cut the calorie density of meals and boost their satisfaction factor.
  • Jenny Craig provides pre-packaged, portion-controlled meals. While experts took issue with its cost, they liked its wide variety of entrees, snacks, and desserts.
  • Health Management Resources (HMR) Program: This commercial plan provides meal replacements, which users combine with vegetables and fruits they prepare, and it includes behavioral training and weekly phone coaching sessions. 

These five diets tied for the #5 slot:

  • The Biggest Loser Program: Based on the hit television show, this diet suggests four servings a day of fruits and vegetables, three of protein foods, two of whole grains, and no more than 200 calories of “extras” like desserts.
  • The Flexitarian Diet basically prescribes a mostly-vegetarian diet with small amounts of meat and fish.
  • Raw Food diets: These vary, but are essentially vegan diets minus the cooking.
  • Slim-Fast Diet: Like Jenny Craig and HMR, this plan provides products (shakes, meal bars and snack bars) to replace breakfast, lunch and snacks, but you also prepare a 500-calorie meal daily, to make room for small portions of favorite foods.
  • Vegan diets: Simply put, vegan diets provide only plant foods, which tend to be low in calories and high in micro-nutrients, antioxidants, and satiating fiber. 

Commercial plans that provide all of most of the food, like Jenny Craig, Slim-Fast, or HMR, may prove hard to maintain, due to boredom.

Top three overall diets ranked lower for weight loss
A broad range of diets fell in the middle of USNWR's Best Weight Loss Diets ranking.

These plans were ranked as the top three diets overall, because they are easy to follow and are backed by substantial evidence that they boost brain and heart health:

  1. DASH (tied at #12 for Weight Loss): The Dietary Approaches to Stop Hypertension (DASH) diet isn’t designed specifically for weight loss, but as USNWR says, “Because DASH emphasizes so many healthful foods, it can easily support weight loss.”
  2. Mediterranean Diet (tied at #12 for Weight Loss): All versions emphasize fruits, veggies, whole grains, beans, nuts, legumes, olive oil (extra-virgin grade), herbs, and spices, call for eating fish and seafood at least twice a week, advise moderate consumption of poultry, eggs, cheese, red wine, and yogurt, and strictly limit sweets and red meats.
  3. MIND (tied at #21 for Weight Loss) is the acronym for “Mediterranean-DASH Intervention for Neurodegenerative Delay”, and it blends aspects of the DASH and Mediterranean diets. The plan emphasizes berries, green leafy vegetables, whole grains, fish, poultry, olive oil, and (moderate) wine, and limits saturated fats (butter, red meats), margarine, cheeses, pastries, sweets, and fried or fast food.

The biggest losers
Some very popular diets landed at or near the bottom of USNWR rankings.

These included the Zone diet, the Glycemic-Index Diet, the Whole30 Diet, and the Alkaline-Acid diet. 

The panel members cited several reasons for their low rankings: lack of clarity, potential confusion, meager research, higher cost, and potential nutritional deficiencies.

We seriously question the low rankings of these two:

  • Dr. Weil's Anti-Inflammatory Diet: This one ranked #30 for Weight Loss and #15 for Best Diets Overall. Dr. Weil's Mediterranean-type diet emphasizes whole plant foods, and favors fish and vegetable protein over meats and poultry. It also adds antioxidant rich foods like green tea, ginger turmeric, and dark chocolate, and standard antioxidant supplements such as vitamins C and E. We can see no good reason why it ranked so low.
  • Paleo diets: Despite their popularity, Paleo diets were ranked dead last (#38), as they've been the past few years. Paleo diets ban all foods not presumed to have been eaten in pre-history — including refined sugar, dairy, legumes and grains — in favor of meat, fish, poultry, fruits and veggies. The panelists didn't like that entire food groups are excluded, making it harder for people to follow, and to (allegedly) get all the nutrients they need. Nonetheless, basic nutrition research suggests that Paleo diets should aid weight loss.

Not everyone accepts the USNWR rankings, especially with regard to the Paleo diet.

“The 2014 USNWR diet ratings represent nothing more than the subjective rankings of 32 popular diets by a group of professionals, ultimately hand-picked by the editorial infrastructure at [USNWR],” wrote Paleo diet advocate Loren Cordain, Ph.D.

As Cordain said about the 2014 rankings, “Notably lacking in the makeup of this panel are academic and medical professionals with a background and publication record in human evolution, ancestral human diets and the application of this diet within a clinical setting.”

(Dr. Cordain seemed to suggest that USNWR should've picked panelists biased toward his diet, some of whose strictures — such as those against legumes — have been undermined by new paleological findings.)

The panel's critiques of the Paleo diet also apply to a Raw Food diet, which could be even harder to maintain and less nutritionally complete.

So why did a Raw Food diet rank number three among Best Weight Loss Diets while Paleo hit the very bottom?

There’s no good answer, which highlights the shortcomings of the USNWR panel's rather confusing, inconsistent rankings.

In Part 2 of this series, we’ll explore what research reveals about these popular weight loss diets.

And as we'll explain, while the USNWR review got some things right, they got others pretty wrong.