Research Review: Precision Nutrition will make you immortal

Research Review:
Precision Nutrition will make you immortal

By Helen Kollias, Ph.D.


Did you hear the latest news? See the headlines claiming that following Precision Nutrition will make you live forever? You know, immortal and all? Well if not, you’re missing out. After all, a recent study published in the American Journal of

Okay, I’m not being serious here. In fact, I’m exaggerating a bit. But the truth is that the media makes crazy claims all the time. Unsupported claims. Like the kind above.

Seriously, I don’t know how many times I’ve heard about a new study in the media, only to actually read the study and realize just how wrong they got it!

People don’t know what to believe because today’s report contradicts last month’s – or so it often seems. The reporting lacks nuance and understanding. So we end up with a hodge-podge of “factoids” (not facts) and a bunch of confused people who throw up their hands in disgust, ready to stop eating “healthy” because they just can’t figure out what “healthy” means.

Research question

In fact, this very thing happened last month with the publication of a new study comparing 3 diets – the low-carb diet, the low-fat diet, and the Mediterranean diet. These were the headlines:

“Low-carb diet proven best for weight control”

“Low-carb diet beats other diets in study: The Atkins diet may have proved itself after all.”
CNN Health

“Study: Low-carb diet more effective overall”
Seattle Times

So, which study were these headlines talking about? Why, the New England Journal of Medicine study published in July of this year. Here’s the citation if you want to look it up yourself…

Shai I et al. Weight loss with a low-carbohydrate, Mediterranean, or Low-fat diet. N Engl J Med. 2008 Jul 17; 359(3): 229-41.

And what happened in this study?

  • Low-carb diet – Weight lost = 10.3 lbs (4.7 kg) in the 2 year study
  • Mediterranean diet – Weight lost = 9.7 lbs (4.4 kg) in the 2 year study
  • Low-fat diet – Weight lost = 6.4 lbs (2.9 kg) in the 2 year study

Interesting. It doesn’t exactly seem like the low-carb diet trounced the other two diets, does it? I mean, really, do these differences matter? In this context, isn’t saying that the low-carb diet is better than the other two diets kinda like saying that the Lincoln Navigator has better gas mileage than a Dodge Durango?

So much for the headlines. However, that’s not the best part. The real punch line is this:

This study lasted 2 years!

That’s right — these folks lost only 6-10 lbs in 2 freakin’ years! I can see the infomercials now:

“You too can lose 10 pounds in 2 years just like me.”

Pretty sad, huh?

Especially considering that we here at PN have demonstrated that it’s possible to lose 10 lbs of body fat in a month. In fact, several of our PN Body Transformation Contest finalists dropped 30-40 lbs in 4 months.

Weight to lose?

Now, you probably have questions. For example, maybe these people didn’t have much weight to lose. In this case, the 10 lb loss could have been quite good.

Uh, not really.

These people were anything but svelte. In fact, they were moderately obese (BMI ≥ 30) and they worked together at a nuclear power plant. Think Homer Simpson. Really, they worked at a nuclear power plant. No lie. HOMER SIMPSON.

They definitely had fat to lose. On average, they were carrying about 80 lbs of body fat on their nuclear power plant workin’ bodies. So a 40-50 lb fat loss would have been ideal.

They lost 10 lbs.

And… did we mention… it took 2 years?

Not so bad

At this point, you might be thinking that we hate this study. Not true. The study was actually a pretty good one. Here’s why:

  1. It was huge, using a population of 322 people. That makes it one of the biggest diet intervention studies ever done.
  2. The dieters were middle aged, on average 52 years old, which is a tough group to recruit and a group that usually doesn’t try to change their nutritional habits.
  3. It was long, clocking in at 2 years. I can’t stress this point enough. 2 years. You try to get 322 people to do anything for 2 years. Good luck!
  4. It was well controlled. It had a 6 week dietitian-led “diet training course”, diet-specific food available at the cafeteria, questionnaires to monitor diet adherence and another dietitian that made motivational phone calls to dieters to keep them on track. This is about a good as you can control a diet study – short of locking the dieters up in a cell and force-feeding them.
  5. It had blood analysis! This is key. Before this study, we didn’t know for sure what happened to people’s cholesterol if they ate a low-carb diet for a significant period of time –- say 2 years.

So we like this study; we just don’t like the headlines that were spun out from it. Nor do we like the fact that the media thinks it’s actually an exciting headline when someone who’s 80 lbs overweight loses 10 lbs in 2 years. We can hear it now:

“You’ve done great, folks. Now you do have about 50 more pounds to lose. But that’ll be a breeze. Just keep following your diet for another decade or so, and you’ll be totally ripped.”

Yeah, and about 70 years old.

What about the real story?

The most disappointing thing about the media treatment of this study was the fact that the real story, the important story, wasn’t soundbite-friendly enough to make it into the news. And here’s what really happened:

Despite marginal weight loss, there were some interesting improvements in blood profiles and other health markers.

Here’s a summary of the measurements, including which diet showed the most and least improvement. (Note: Where two diets are listed, it was a tie.)

Measurement Most Improvement Least Improvement
Decrease in waist circumference Low-carb
Blood pressure (systolic/diastolic) Mediterranean Low-carb
HDL cholesterol Low-carb Mediterranean
LDL cholesterol Mediterranean Low-fat
Total cholesterol:HDL ratio Low-carb Low-fat
Triglycerides Mediterranean
Fasting blood glucose levels in diabetics Mediterranean Low-carb
Insulin resistance – diabetics Mediterranean Low-carb

Special notes

Here are a few important things you should notice.

  • The low-fat diet was actually the worst for controlling cholesterol and triglycerides. Oops. Isn’t this diet what docs prescribe to every single patient of theirs with high cholesterol?
  • The low-carb diet and Mediterranean diets seem to be the best for controlling blood lipids and cardiovascular risk.
  • In addition it seems that the Mediterranean diet is best for controlling blood sugar and blood insulin.


In the end, while this study was well designed and well executed, the media’s interpretation was not. The weight changes in this study were the study’s blight, not its asset.

Its real contribution to our knowledge is the information it gave us on how these different diets can impact our health. To this end, the headlines should have read:

“Low-fat diet is less effective at improving cardiovascular disease risk.”

“The Mediterranean diet reduces diabetes risk.”

“The low-carb diet is more effective at lowering cholesterol than the low-fat diet.”

Interestingly, the last line of the study summarized the findings quite nicely.

“The improvements in blood lipids (with the low-carb diet) and in glycemic control (with the Mediterranean diet) suggest that personal preference and metabolic considerations should dictate individual dietary prescriptions.”

Funny, isn’t this what we’ve been saying around here for years?

Eat, move, and live… better.

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