Long-Term Effects of 4 Popular Diets on Weight Loss and Cardiovascular Risk Factors

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Nelson Vergel

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Long-Term Effects of 4 Popular Diets on Weight Loss and Cardiovascular Risk Factors


A Systematic Review of Randomized Controlled Trials

Renée Atallah et al
Published online before print November 11, 2014,doi: 10.1161/CIRCOUTCOMES.113.000723

Abstract


Background—We conducted a systematic review to examine the efficacy of the Atkins, South Beach, Weight Watchers (WW), and Zone diets, with a particular focus on sustained weight loss at ≥12 months.

Methods and Results—We systematically searched MEDLINE, EMBASE, and the Cochrane Library of Clinical Trials to identify randomized controlled trials (RCTs) published in English with follow-up ≥4 weeks that examined the effects of these 4 popular diets on weight loss and cardiovascular risk factors. We identified 12 RCTs (n=2559) with follow-up ≥12 months: 10 versus usual care (5 Atkins, 4 WW, and 1 South Beach) and 2 head-to-head (1 of Atkins, WW, and Zone, and 1 of Atkins, Zone, and control). At 12 months, the 10 RCTs comparing popular diets to usual care revealed that only WW was consistently more efficacious at reducing weight (range of mean changes: −3.5 to −6.0 kg versus −0.8 to −5.4 kg; P<0.05 for 3/4 RCTs). However, the 2 head-to-head RCTs suggest that Atkins (range: −2.1 to −4.7 kg), WW (−3.0 kg), Zone (−1.6 to −3.2 kg), and control (−2.2 kg) all achieved modest long-term weight loss. Twenty-four-month data suggest that weight lost with Atkins or WW is partially regained over time.

Conclusions—Head-to-head RCTs, providing the most robust evidence available, demonstrated that Atkins, WW, and Zone achieved modest and similar long-term weight loss. Despite millions of dollars spent on popular commercial diets, data are conflicting and insufficient to identify one popular diet as being more beneficial than the others.
 
Defy Medical TRT clinic doctor
Hi Nelson, You should checkout the Raw Till 4 diet. Raw fruits and veggies till 4pm then you can have a vegan high carb, low fat cooked dinner. I have tried Atkins and Zone before moving to Raw Till 4 and I must say I feel better on Raw Till 4 then I ever did on the others.
 

Vince

Super Moderator
Doubling saturated fat in the diet does not increase saturated fat in blood, study finds
medicalxpress.com

Doubling or even nearly tripling saturated fat in the diet does not drive up total levels of saturated fat in the blood, according to a controlled diet study.
However, increasing levels of carbohydrates in the diet during the study promoted a steady increase in the
blood of a fatty acid linked to an elevated risk for diabetes and heart disease.

The finding "challenges the conventional wisdom that has demonized saturated
fat and extends our knowledge of why dietary saturated fat doesn't correlate with disease," said senior author Jeff Volek, a professor of human sciences at The Ohio State University.

In the study, participants were fed six three-week diets that progressively increased
carbs while simultaneously reducing total fat and saturated fat, keeping calories and protein the same.

The researchers found that total saturated fat in the blood did not increase - and went down in most people - despite being increased in the diet when carbs were reduced. Palmitoleic acid, a fatty acid associated with unhealthy metabolism of carbohydrates that can promote disease, went down with low-carb intake and gradually increased as carbs were re-introduced to the study diet.

"It's unusual for a marker to track so closely with carbohydrate intake, making this a unique and clinically significant finding. As you increase carbs, this marker predictably goes up," Volek said.

When that marker increases, he said, it is a signal that an increasing proportion of carbs are being converted to fat instead of being burned as fuel. Reducing carbs and adding fat to the diet in a well-formulated way, on the other hand, ensures the body will promptly burn the saturated fat as fuel - so it won't be stored.

"When you consume a very low-carb diet your body preferentially burns saturated fat," Volek said. "We had people eat 2 times more saturated fat than they had been eating before entering the study, yet when we measured saturated fat in their blood, it went down in the majority of people. Other traditional risk markers improved, as well."

The research is published in the Nov. 21, 2014, issue of the journal PLOS ONE.

Volek and colleagues recruited 16 adults for the study, all of whom had metabolic syndrome, defined as the presence of at least three of five factors that increase the risk for heart disease and diabetes (excess belly fat, elevated blood pressure, low "good" cholesterol, insulin resistance or glucose intolerance, and high triglycerides).

After getting them to a baseline reduced-carb diet for three weeks, researchers fed the participants the exact same diets, which changed every three weeks, for 18 weeks. The diets started with 47 grams of carbs and 84 grams of saturated fat each day, and ended with 346 carb grams per day and 32 grams daily of saturated fat.

Each day's meals added up to 2,500 calories and included about 130 grams of protein. The highest-carb level represented 55 percent of daily calories, which roughly matches the estimated daily percentage of energy provided by carbs in the American diet.

Compared to baseline, there were significant improvements in blood glucose, insulin and blood pressure that were similar across diets. Participants, on average, lost almost 22 pounds by the end of the trial.

When looking at palmitoleic acid, however, the scientists found that it consistently decreased on the high-fat/low-carb diet in all participants. The fatty acid then showed a step-wise increase in concentration in the blood as carbs were progressively added to the diet. Elevated levels of palmitoleic acid in the blood have been linked to obesity and higher risk for inflammation, insulin resistance, impaired glucose tolerance, metabolic syndrome, type-2 diabetes, heart disease and prostate cancer.

The study does not address what happens to palmitoleic acid levels when high carbs are combined with a diet high in saturated fat. Instead, Volek hoped to identify the carb-intake point at which participants began to store fat.

"That turned out to be highly variable," he said. "Everyone showed increased palmitoleic acid levels as carbs increased, but values varied widely between individuals, especially at the highest carb intake. This is consistent with the idea that people vary widely in their tolerance to carbohydrates."

Participants' existing health risks were not a factor in the study because everyone ate the exact same diet for 18 weeks. Their bodies' responses to the food were the focus of the work.

"There is widespread misunderstanding about saturated fat. In population studies, there's clearly no association of dietary saturated fat and heart disease, yet dietary guidelines continue to advocate restriction of saturated fat. That's not scientific and not smart," Volek said. "But studies measuring saturated fat in the blood and risk for heart disease show there is an association. Having a lot of saturated fat in your body is not a good thing. The question is, what causes people to store more saturated fat in their blood, or membranes, or tissues?

"People believe 'you are what you eat,' but in reality, you are what you save from what you eat," he said. "The point is you don't necessarily save the saturated fat that you eat. And the primary regulator of what you save in terms of fat is the carbohydrate in your diet. Since more than half of Americans show some signs of carb intolerance, it makes more sense to focus on carb restriction than fat restriction."

Volek sees this palmitoleic acid as a potential biomarker to signal when the body is converting carbs to fat, an early event that contributes to what he calls "metabolic mayhem."

"There is no magical carb level, no cookie-cutter approach to
diet, that works for everyone," he said. "There's a lot of interest in personalized nutrition, and using a dynamically changing biomarker could provide some index as to how the body is processing carbohydrates."
Here's the full paper at PLOS ONE
Effects of Step-Wise Increases in Dietary Carbohydrate on Circulating Saturated Fatty Acids and Palmitoleic Acid in Adults with Metabolic Syndrome
 

Vince

Super Moderator
Saturated fat & CHD in Europe
16 Zoe Harcombe by Zoë Harcombe

This post shows that, for all 192 countries in the world, for men and women, for CVD deaths and all-cause mortality, the HIGHER the cholesterol levels, the LOWER the death rate; the LOWER the cholesterol levels, the HIGHER the death rate. The Pearson correlation coefficient gets higher as we move from male CVD deaths to female CVD deaths to male all deaths to female all deaths.

This blog repeats the exercise of examining the association between heart disease (this time CHD) and an accused causal agent (this time saturated fat). The data is available for Europe here[Ref 1]. As you can see below, the association is again inverse – the higher the saturated fat intake, the lower the CHD death rate for males…


and females…



The correlation for males (r) is 0.545 and it is even stronger (0.62) for females.

The top and bottom seven

In the brilliant “The Great Cholesterol Con”, Dr Malcolm Kendrick reviewed the top and bottom seven countries for saturated fat intake in Europe and the countries with the highest and lowest levels of heart deaths. He used the MONICA data from c. 1998. I repeated this for the 2008 data [Ref 1].

* The 7 countries with the LOWEST saturated fat intake were Bosnia& Herzegovinia; Georgia; Azerbaijan; Tajikstan; Moldova; Croatia; Armenia.

Their saturated fat intake ranged from 3.9-7.3%. The average was 5.8% – all way below the recommended 10% saturated fat limit set by dietary guidelines.

* The 7 countries with the HIGHEST saturated fat intake were Austria; Finland; Belgium; Iceland; Netherlands; Switzerland; France (France is the single country with the highest saturated fat intake in Europe and the lowest rate of CHD deaths).

Their saturated fat intake ranged from 13.9-15.5%. The average was 14.7% – all way above the recommended 10% saturated fat limit set by dietary guidelines.

* The 7 countries with the LOWEST saturated fat intake had the following death rates:

– Male deaths per 100,000 ranged from 73-178, with an average death rate of 117.

– Female deaths per 100,000 ranged from 17-67, with an average death rate of 41.

* The 7 countries with the HIGHEST saturated fat intake had the following death rates:

– Male deaths per 100,000 ranged from 22-65, with an average death rate of 39.

– Female deaths per 100,000 ranged from 4-13, with an average death rate of 9.

Death rates for men were 3 times higher in the lowest saturated fat intake countries than the highest.

Death rates for women were 4.5 times higher in the lowest saturated fat intake countries than the highest.

As Malcolm found from the 1998 data – every single country in the top 7 saturated fat intake countries had a lower death rate than every single country in the bottom 7 saturated fat intake countries. This held for men and women. It holds again with the data from 10 years on.

The nutrition

Two facts are not widely enough known about fat/saturated fat and this explains much of the nonsense claimed about saturated fat. If people knew what saturated fat actually is, they would find their allegations about this life-vital nutrient as absurd as they are:

1) All food that contains fat contains all three natural fats (saturated, monounsaturated and polyunsaturated). There are no exceptions.

Meat, fish, eggs, dairy, nuts, seeds, olives, avocados – all of these foods contain all three fats. It is completely impossible to eat unsaturated fat without saturated fat, or vice versa.

2) The only food groupthat contains more saturated than unsaturated fat is dairy products. Meat has more unsaturated than saturated fat; eggs have more unsaturated than saturated fat; LARD has more unsaturated than saturated fat – not that any real fat is better or worse than any other– but just to set the record straight.

So – if you want a row about saturated fat – you’re having a row about dairy products and you may want to bear this in mind: There is evidence of a re-emergence of rickets and osteoporosis is rising [Ref 2]. The Family Food survey has reported that the present UK diet is deficient in retinol and vitamin D, providing less than one third of the UK Reference Nutrient Intake and barely a fifth of the recently revised American RDA for vitamin D [Ref 3].

As our 2013 paper suggests: “Using a 100 g steak, as an example, with 5.4 g of fat, it is difficult to accept that the 39% of the fat which is saturated is damaging to the cardiovascular system while the 61% of the fat which is unsaturated is protective. Keeping in mind that the total fat content of the steak will provide all but 3 of the 13 vitamins and 16 minerals that are a pre-requisite for the maintenance of good health.”

[Ref 1] Allender S, Scarborough P, Peto V, Rayner M. European Cardiovascular Disease Statistics: British Heart Foundation Health Promotion Research Group, 2008.
[Ref 2] S. H. Pearce and T. D. Cheetham, “Diagnosis and Management of Vitamin D Deficiency,” BMJ, Vol. 340, 2010, p. b5664. doi:10.1136/bmj.b5664
[Ref 3] DEFRA (The Department for Environment, Food and Rural Affairs), “A National Statistics Publication, the Family Food Survey,” The Department for Environment, Food and Rural Affairs, London, 2010.

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Vince

Super Moderator
Dr. Davis, the wheat belly doctor, as I have stated in the past I am a former patient of his and I do believe in many of his principles.
 
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