Greek Study Falsely Disparages Low-Carb/High-Protein Diets – Part 1

Filed in Social IssuesTags: Health/Nutrition

For background information, see the Introduction.

Part 1: Is It Really Low-Carb?

The study purports to evaluate "the effects on mortality of habitual low carbohydrate–high-protein diets that are thought to contribute to weight control." - ostensibly, this study evaluates low-carbohydrate/high-protein diets designed for weight control (that is, weight loss). In other words, this study purports to evaluate low-carb weight-loss diets. (I may sound repetitive here, but I have a purpose). What, then, does this study consider to be "low-carbohydrate/high-protein"?

According to the Results section:

With respect to the choice LC/HP score that relies on energy-adjusted components, at the high extreme of the distribution around 20% of energy intake was derived from proteins, whereas around 25% was derived from carbohydrates. At the low extreme of the distribution, around 10% of energy intake was derived from protein, whereas more than 50% was derived from carbohydrates.

Thus, for the purposes of this study, "low-carbohydrate/high-protein" means 25% carbohydrate and 20% protein.

Yes, you read that right: this study claims that a diet that includes 25% of its caloric intake from carbohydrate is "low-carb", and that a diet that includes 20% of its caloric intake from protein is "high-protein".

For a 2,000 kCal daily intake, these values equate to 500 kCal, or 125g, of carbohydrate per day - and bear in mind, this is the most extreme low-carb limit in the study. (Likewise, these values equate to 400 kCal, or 100g, of protein per day, for a 2,000 kCal daily intake. This is the extreme high-carb limit in the study.)

So, my first question is this: what mainstream low-carb diet in any way resembles this macro-nutrient intake?

To put the bounds of the study into perspective, here are the mean macro-nutrient intake values for the population:

In this population, the mean intake of protein was 76 g/day with standard error of the mean (s.e.m.) 0.16 g/day, the mean intake of carbohydrates was 208 g/day with s.e.m. 0.44 g/day, and the mean intake of lipids was 109 g/day (28% saturated, 15% polyunsaturated, 48% monounsaturated fatty acids and 9% other components of the lipid group) with s.e.m. 0.25 g/day.

Let's explore those numbers for carbohydrate intake: mean intake 208 g/day, s.e.m. 0.44 g/day. Standard Error on the Mean (s.e.m.) is equal to the standard deviation (σ) divided by the square root of the number of samples (total population size). The total population size is 22,944; the square root of 22,944 is 151.5. Thus:

s.e.m. = 0.44 g/day = σ / 151.5

σ = 0.44 g/day * 151.5 = 66.7 g/day

Thus, carbohydrate intake for the study was a mean of 208 g/day with a standard deviation of 66.7 g/day.

Standard Deviation is the measure of the distribution around the mean. We can probably safely assume that our population is normally distributed (bell-shaped curve, with the peak at the mean, and exactly half of the population on either side of the peak). In a normally distributed set of data, 2/3 of all data lie within 1 σ of the mean, and 90% of all data lie within 2 σ of the mean.

Therefore, given the values for mean and standard deviation, we know that, statistically speaking, 2/3 of the study participants had a carbohydrate intake between 141 and 274 g/day, and that 90% of the study had a carbohydrate intake between 75 and 340 g/day.

How accurate is that estimate? The accuracy depends on the normality of the distribution.

According to Table 1 of the study, only 552 men (5.9%) and 2,218 women (16.3%) - a total of 2,770 participants (12.1%) had a carbohydrate intake of less than 140 g/day.

Based on the mean and standard deviation above, we can estimate that since 2/3 of the study participants had a carbohydrate intake between 141 and 274 g/day, that 1/3 were outside of that span - half of which (1/6, or 16.7%) had a carbohydrate intake of less than 140 g/day.

If anything, the distribution is biased against the low-carb side of the curve - meaning that the true number of participants at any given standard deviation is actually less than predicted by the normal curve.

The two most popular mainstream low-carb diets are the Atkins Diet and Protein Power (the South Beach diet does not consider itself to be "low-carb" and is excluded here).

The Atkins Diet allows anywhere from 20g carbohydrate per day in the Induction phase to 60-90g carbohydrate per day in the Maintenance phase (with allowance for more than 90g per day for active exercisers).

Protein Power allows anywhere from 40g carbohydrate per day at the Intervention level to 80g carbohydrate per day at the Maintenance level (according to Table 13.6 of my Protein Power Lifeplan book, page 355).

That means that less than 5% of the study participants had a carbohydrate intake anywhere near what is specified by mainstream low-carbohydrate diets.

In other words, this study in no way resembles either mainstream, low-carbohydrate diet. Therefore, any conclusions to which this study might lead do not apply to mainstream low-carbohydrate diets.

Coming Soon - Part 2: Is It Really High-Protein?

Greek Study Falsely Disparages Low-Carb/High-Protein Diets – Introduction

Filed in Social IssuesTags: Health/Nutrition


Recently, Jimmy Moore at Livin' La Vida Low-Carb linked to an epidemiological Greek Study that purported to compare mortality rates of Low-Carb/High-Protein and High-Carb/Low-Protein diets, along with a challenge from Dr. Steven Acocella - a vocal critic of low-carb diets - to refute it under the assumption that it is a legitimate study:

I will not editorialize on the study, but simply listen to you and your reader’s comments. I will say that there's no reason that we need to dispute the efficacy of the study itself. Let's go from the position that the study is not flawed. Let's discuss the science and findings.

The conclusions of the authors are reproducible and consistent. What do you all think? If you do post this study I applaud your willingness to explore the science and not ignore nor dismiss it.

Many of Jimmy's readers have been up to the challenge, and I would like to throw in my two-cents' worth.

First, let's examine the abstract, to get a basic understanding of the study. Here is the study objective:

We have evaluated the effects on mortality of habitual low carbohydrate–high-protein diets that are thought to contribute to weight control.

As the objective states, the object of the study was to evaluate the effect on mortality rate of so-called low-carbohydrate/high-protein diets - ostensibly, low-carbohydrate weight-loss diets.

The study setting is the general Greek population. Here are the subject methods:

Follow-up was performed from 1993 to 2003 in the context of the Greek component of the European Prospective Investigation into Cancer and nutrition. Participants were 22 944 healthy adults, whose diet was assessed through a validated questionnaire. Participants were distributed by increasing deciles according to protein intake or carbohydrate intake, as well as by an additive score generated by increasing decile intake of protein and decreasing decile intake of carbohydrates. Proportional hazards regression was used to assess the relation between high protein, high carbohydrate and the low carbohydrate–high protein score on the one hand and mortality on the other.

In other words, this is an epidemiological study based on the Greek-population subset (about 23,000 people) of the EPIC study from 1992 to 2003. Analysis is based on separating this subset into various decile groups based on descending protein intake, ascending carbohydrate intake, and a sum of the two deciles.

Understanding these groupings is key to understanding the study, so let's take some time with the explanation. For the three analysis groups, participants were separated into decile groups - that is, groups of 1/10 of the total - based on the given criterion. So, for the descending protein intake group, all 23,000 participants are ordered based on protein intake, and the highest 2,300 participants are placed in the first decile (and so on, for all 23,000 participants). Likewise for descending carbohydrate intake (except, in this case, the 2,300 lowest carbohydrate-intake participants are placed in the first decile). Finally, for the third analysis group, each participant's two decile "scores" (the first decile is scored a "1" and the tenth decile is scored a "10") are added together, and groups are defined from a "score" of 2 (low-carb/high-protein) to 20 (high-carb/low-protein). Make sense?

Moving on: The study claims the following results:

During 113 230 persons years of follow-up, there were 455 deaths. In models with energy adjustment, higher intake of carbohydrates was associated with significant reduction of total mortality, whereas higher intake of protein was associated with nonsignificant increase of total mortality (per decile, mortality ratios 0.94 with 95% CI 0.89 –0.99, and 1.02 with 95% CI 0.98 –1.07 respectively). Even more predictive of higher mortality were high values of the additive low carbohydrate–high protein score (per 5 units, mortality ratio 1.22 with 95% CI 1.09 –to 1.36). Positive associations of this score were noted with respect to both cardiovascular and cancer mortality.

Finally, the study makes the following conclusion:

Prolonged consumption of diets low in carbohydrates and high in protein is associated with an increase in total mortality.

Sounds pretty bad for low-carb diets, eh? Perhaps - or perhaps not. We need to dig deeper into the study in order to decide.

Read on, in Part 1: Is It Really Low-Carb?

Brother-In-Law Highlighted as Military Hero

Filed in PersonalTags: Military, War on Terror

Michael Shropshire

Congratulations to my brother-in-law, Michael Shropshire, for being highlighted as one of the Department of Defense's Heroes in the War on Terror!

Michael was awarded the Silver Star for his efforts in the battle for the Euphrates River bridge at Najaf with the famed 7th Cavalry (3rd Division, 7th Cavalry - of General Custer fame), the "tip of the sword" for much of the military advance from Kuwait to Baghdad in Operation Iraqi Freedom. This 36-hour battle (press coverage here, here, here, here, here, here) was among the most fierce the military faced. (See pages 17-19 of this PDF for a detailed description of the Najaf operation.)

The silver star is the third-highest military honor:

The Silver Star is awarded to a person who, while serving in any capacity with the U.S. Army, is cited for gallantry in action against an enemy of the United States while engaged in military operations involving conflict with an opposing foreign force, or while serving with friendly foreign forces engaged in armed conflict against an opposing armed force in which the United States is not a belligerent party. The required gallantry, while of a lesser degree than that required for the Distinguished Service Cross, must nevertheless have been performed with marked distinction.

Michael's gallantry is described in this Fort Drum coverage of the Silver Star award ceremony:

Shropshire was honored for his contribution to Operation Iraqi Freedom at Abu Sukhayr, Iraq, in March 2003 when the Army unit he was attached to was attacked and surrounded by enemy forces. Surrounded, cut off, under a hail of enemy gunfire and in the largest sandstorm in four decades, Shropshire coordinated close air support while constantly switching from the radio handset to his rifle.

The sandstorm cut the controller visibility dramatically, and it was compounded by rain. “It was basically raining mud,” he said. Because of this fact, he heavily relied on outside technology like the Joint Surveillance Target Attack Radar System, which helped him to “see” through the muck.

The sergeant then left the security of his armored vehicle to confirm enemy armor locations. Low on ammunition, in a blinding sandstorm and under intense enemy fire, the sergeant directed the munitions that destroyed 10 T-72 tanks. This act dismounted enemy forces about to overrun the unit’s position. He then quickly repaired his bullet-ridden satellite antenna and coordinated other air strikes.

“I couldn’t have done this by myself,” he said. “There were a lot of people on the outside working their pieces to help me accomplish my mission. The joint team worked out really well.”

Tactical air controllers are Air Force specialists who are assigned to Army combat maneuver units around the world. They are typically a two-airmen team that works in an Army ground unit to direct close air support toward enemy targets on the ground. Airmen of the 18th ASOG operate and are deployed from 18 different locations across the United States.

(See also here and here.)

Michael's job entails quite a bit of advanced technology. See the description of the battle from this piece on network centricity, which explains that Michael was credited with the destruction of over 60 tanks and armored vehicles and hundreds of trucks:

Recent combat experience provides a host of real-world examples of the power of network-enabled operations. The example I like best is that of U.S.A.F. Staff Sergeant Michael Shropshire, an Air Force Enlisted Terminal Attack Controller who in 2003 fought his way through northern Iraq with the troops of the 7th Cavalry during Operation Iraqi Freedom. The 7th Cavalry was the unit that got massacred at Little Big Horn under General George Custer over a century ago.

Outside Najaf, Shropshire’s unit became engulfed in a ferocious sandstorm. Tasked with securing a strategic bridge, the unit was isolated and surrounded on all sides by heavy Iraqi forces. Shropshire’s satellite radio became the primary form of communication for the endangered troops since the ground-force FM radios suffered from limited range.

Using the space-based link to the network, Shropshire was alerted by an Air Force JSTARS surveillance aircraft—one of just a handful of assets in the world that can peer through sandstorm conditions—that 10 T-72 tanks were about to overrun his unit. After receiving this information, Sergeant Shropshire left his armored personnel carrier and coolly directed a B-1 bomber to drop 12 GPS-guided JDAMs directly on the enemy tanks. He also quickly coordinated with inbound fighters to destroy an armored formation attacking from the other direction. Altogether, Sergeant Shropshire orchestrated the destruction of over 60 tanks and armored vehicles and hundreds of trucks.

Because of network-centric capabilities, this two-legged knowledge-enabled war fighter was able to gather a worldwide network of sensors, shooters, and space systems in support of a single, isolated cavalry troop—through sand and rain and directly on target. A lot of troopers in the 7th Cavalry owe their lives to Sergeant Shropshire, who helped to prevent another Little Big Horn for the fabled regiment and came home with a Silver Star.

Shropshire was a network-enabled fighter. But just a decade ago his position would have been much different. How would he have received information? How current would that information have been? How would the data have come to him? The pace of change has accelerated rapidly in recent years. For example, my company currently had a Global Hawk unmanned intelligence, surveillance, and reconnaissance aircraft flying in theater equipped with the Advanced Information Architecture—the low cost of electronic storage allowed us to put a computer on the aircraft that stores huge quantities of information. With this aircraft in the region, the individual soldier can use his Personal Digital Assistant to pull down up-to-date information on his location and the surrounding area within a few minutes.

Congratulations, Michael!

OYB May 10

Filed in ReligionTags: Christianity, Devotions, One Year Bible

Today´s reading:
OT: I Samuel 8-9
NT: John 6:22-42
Ps: Psalm 106:32-48
Pr: Proverbs 106:32-48

Gospel Thread - OT:

And the LORD told him: "Listen to all that the people are saying to you; it is not you they have rejected, but they have rejected me as their king."

I Samuel 8:7 (NIV)

God always intended that He alone should be our King. The tragic story of the history of mankind is that we have repeatedly chosen to turn away from Him as our King, and in so doing we have given ourselves over to be enslaved by sin. But God, in His eternal goodness, provides hope for a way out of that slavery; and in His grace, He would use even the kings He appointed to try to help mankind recognize our need to serve God alone as our One, True King.

Gospel Thread - NT:

Jesus answered, "The work of God is this: to believe in the one he has sent."

John 6:29 (NIV)

We do not achieve salvation by our own works; rather, salvation is God's gift to us, according to His grace, and through our faith in Jesus Christ.

Gospel Thread - Psalms/Proverbs:

44 But he took note of their distress when he heard their cry;
45 for their sake he remembered his covenant and out of his great love he relented.

Psalm 106;44-45 (NIV)

Just as God heard Israel's cries of distress, still today God hears our cries of distress as well. When Israel cried out to God, He chose to hear them and to rescue them from their oppression. When we cry out to God, He chooses to hear us and to rescue us from our oppression. His covenant with us through Jesus Christ is everlasting; we need only to believe it and to respond.

The One Year Bible Blog´s comments for today.