Obesity, Protein and Satiety

satiety, in dietary terms, is the lack of hunger or how much the diet satisfies you; it is tied closely to “lack of hunger”, a concept that is foreign to most frequent dieters.

Among those successful on low carb diets, dietary fat is often assigned the role as the macro-nutrient that provides the most satiety. But a core principle of the The Protein Power Lifeplan diet is the focus on getting at least the minimum amount of protein required to maintain muscle mass (generally, one half gram of dietary protein per day per pound of lean body mass, from 60 to 100 grams per day for most people. Exceed these minimums is certainly permissible, and people continue to lose weight consuming a 50% “surplus” over and above the minimum).

Now a new study in the medical journal Obesity sheds some new light on the power of protein. The Influence of Higher Protein Intake and Greater Eating Frequency on Appetite Control in Overweight and Obese Men studied both protein intake and frequency of eating:

Collectively, these data suggest that higher protein intake promotes satiety and challenge the concept that increasing the number of eating occasions enhances satiety in overweight and obese men.

Participants were given equal calorie diets, but one group had 79 grams of protein, and the other 138 grams of protein. One subset of each group was directed to eat 6 times a day, while another was served 3 meals per day.

This was a carefully controlled study, and did not test the participant’s ability to “stick to the diet” in a free-living arrangement. Lack of satiety is often a reason free living participants will cheat (and even some in carefully controlled ward studies find ways to cheat … even hospitals have vending machines). But in this study, the participants were fed controlled portions so all factors remain equal. Blood tests and surveys were used to determine several biochemical levels and how satisfied the participants were with the diet they were given.

There is enough variation in the small group to be uncertain if it proves anything in terms of blood glucose response (although several smaller meals seems to lead to better blood sugar levels). But one thing was consistent: higher protein intake provided a higher level of satiety. And frequent eating of smaller amounts did not provide more satiety; it provided less.

Thursday Round Up

A quick round up of site news and interesting blog posts today:

Et tu, Food Nazi?

Stargazy at Low-Carb for You sounds an alarm at something I have also become concerned about, the low-carb Food Nazis:

But as I look back on my recent blogposts and those of other bloggers, I have started to notice a more rigid, regimented (shall we say Nazi-like?) aspect to the world of low-carbing. Some examples:

* It’s good to eat fat, but be sure the fat has the right omega-3 to omega-6 ratio.
* It’s good to eat nonstarchy vegetables, but remember that broccoli has goitrogens and tomatoes are nightshades. And wheat, even whole wheat, contains many compounds that can damage the human digestive tract.
* It’s good to eat meat, but it should be grass fed, not grain fed.
* It’s good to eat eggs and chicken, but they need to be free range.
* It’s good to eat seafood, but watch out for the mercury.
* It’s good to avoid sugar, but it’s better to avoid artificial sweeteners as well.

Stargazy shares my concern that adding rules on top of rules make the low carb way of eating infinitely more complex, and will turn people away. My guess is that if you looked at the history of those expounding on the laudable but unnecessary extra rules, they are restrictions they have added after mastering the easy-peasy rules of low carb eating: eat adequate protein in every meal, and keep your carbs at about 10 grams per meal.

Really folks, you’ll get 99% of the benefit with those two rules: eat adequate protein and reduce carbs to 10 grams per meal. And if you never do anything else, you’ll get the vast majority of the benefits of a low carb lifestyle.

Non-Alcoholic Fatty Liver Disorder

A new research page has been added on Liver Disease. Our first linked article is from the British Journal of Radiology, and is a short term study of patients with non-alcoholic fatty liver disorder. Eschewing the painful and laborious biopsy required for diagnosis this disorder, the researchers chose to use MRIs instead. Significant reductions in the amount of fat in the liver were observed in all suspects within 10 days (and some had significant reductions within 3 days). Anyone facing fatty liver issues should consider a low carb diet. As with all serious medical issues, you should talk to your doctor. You may have to insist on trying the low carb lifestyle because some doctors are resistant to the idea. If he doesn’t agree to do the necessary follow-ups, then find another doctor who will work with you.

Scientific American and the Low Carb Age

The May, 2010 issue of Scientific American has an article with the headline “Carbs against Cardio“:

… while Americans have dutifully reduced the percentage of daily calories from saturated fat since 1970, the obesity rate during that time has more than doubled, diabetes has tripled, and heart disease is still the country’s biggest killer. Now a spate of new research, including a meta-analysis of nearly two dozen studies, suggests a reason why: investigators may have picked the wrong culprit. Processed carbohydrates, which many Americans eat today in place of fat, may increase the risk of obesity, diabetes and heart disease more than fat does—a finding that has serious implications for new dietary guidelines expected this year.

The article includes a quick recap of different studies that have shown fat intake unrelated to heart disease, including a large meta-analysis of 350,000 people. There is now compelling evidence that carbs, not saturated fat, are the greater health risk.

But will the upcoming dietary recommendations include the “new” information? It seems like a slam-dunk, but this is the government we’re talking about …

Will the more recent thinking on fats and carbs be reflected in the 2010 federal Dietary Guidelines for Americans, updated once every five years? It depends on the strength of the evidence, explains Robert C. Post, deputy director of the U.S. Department of Agriculture’s Center for Nutrition Policy and Promotion. Findings that “have less support are put on the list of things to do with regard to more research.” Right now, Post explains, the agency’s main message to Americans is to limit overall calorie intake, irrespective of the source. “We’re finding that messages to consumers need to be short and simple and to the point,” he says.

In other words, rather than telling Americans to eat the right kind of food, the USDA will persist in telling them to do the most unnatural and dangerous thing you can do: starve yourself.

“Short and simple and to the point” translates to “people are idiots.” Funny that the American public has indeed reduced fat consumption (to its detriment), all the while absorbing the numbers and ratios promulgated as “healthy” by the government. Perhaps the real reason the story has to be told obliquely is that “the people” will see they have been misled. The government told us to eat this way, and its killing us.

The article goes on to slam the “sugared beverage industry”, one of the media’s favorite whipping boys these days, as lobbying heavily in favor of keeping the current dietary guidelines. But the problem is not just sugary drinks, but carbs; the difference between 16 ounces of Coke and 16 ounces of fresh orange juice is slight (and even then, the orange juice gives you more sugar than the Coke.) And loading up on a white rice side dish may have the same effect on your blood sugar levels as that Coke.

Its the carbs, stupid. The carbs.

The article is welcome, of course. And it is a sign of things to come as we transition into the Low Carb Age.

Its about time.

Low Carb: Is Kidney Failure a Possibility?

One of the concerns expressed about adopting a low carb diet is that renal function may be comprised. Concerned folks have heard that low carb diets put stress on the kidneys and can lead to failure, resulting in dialysis or worse for the dieters.

Anyone with limited kidney function should check with their doctor for the proper diet to adopt. You should eat for your greatest risk factor, and if you have renal function at just a percentage of normal, that is probably your highest risk factor. Talk to your doctor.

But for people with normal kidney function, is adopting a low carb diet ill-advised?

In a new study published in the Journal of the American Dietetic Association, the problem with the claim is found in the first sentence of the synopsis:

A frequently cited concern of very-low-carbohydrate diets is the potential for increased risk of renal disease associated with a higher protein intake. However, to date, no well-controlled randomized studies have evaluated the long-term effects of very-low-carbohydrate diets on renal function.

The study took 68 obese men and women and divided them into groups eating either a low fat or ultra low carb diet (14g of carbs per day, about 1/3 the normal induction phase level of 40g.) The participants had kidney function blood tests before adoption of their diet, and then follow ups throughout the year. After one year the blood tests showed similar normal readings for all participants.

Both groups had similar average weight loss, an indication that the participants complied with the dietary guidelines for their group. The conclusion of the study:

This study provides preliminary evidence that long-term weight loss with a very-low-carbohydrate diet does not adversely affect renal function compared with a high-carbohydrate diet in obese individuals with normal renal function.

The study was accepted for publication in September of 2009, and was published in April of 2010 after the standard review by the journal. The study was headed by Grant D. Brinkworth, PhD, of the Commonwealth Scientific and Industrial Research Organisation−Human Nutrition, Adelaide, South Australia.

People with normal kidney function should not worry about renal failure with a low carb diet. The concern may be an exaggeration of the usual advice to keep an eye on kidney function, through regular blood tests, when adopting a low carb diet because of the diuretic effect the diet has. This effect is similar to the effect diuretic blood pressure medications such as hydrochlorothiazide (HCTZ) have, and is one reason many low carbers can quickly eliminate their blood pressure meds. The diuretic effect can cause a dieter to lower potassium levels. Supplementation is often recommended, either with a potassium supplement or simply replacing table salt with a potassium chloride salt substitute (my favorite: Morton’s Light Salt which is half table salt and half potassium chloride).

But the unscientific claim that a low carb diet is bad for your kidneys is unfounded. People with normal kidney function will not be “stressing their kidneys” by adopting a low carb diet.

Genetic Testing and Weight Loss

Dr. Christopher Gardner is an Associate Professor, Medicine at Stanford University, and has published a number of articles on diet and nutrition. He is the lead author of the A to Z Weight Loss Study, published in JAMA in 2007. The year long trial divided 311 women into four groups, and each group was counseled on how to follow the diet assigned to them, either the Atkins, LEARN, Ornish or Zone diets. Overall, it showed the effectiveness of a low carb diet:

In this study, premenopausal overweight and obese women assigned to follow the Atkins diet, which had the lowest carbohydrate intake, lost more weight at 12 months than women assigned to follow the Zone diet, and had experienced comparable or more favorable metabolic effects than those assigned to the Zone, Ornish, or LEARN diets [corrected] While questions remain about long-term effects and mechanisms, a low-carbohydrate, high-protein, high-fat diet may be considered a feasible alternative recommendation for weight loss.

But Gardner noticed something else; within each group of women you have “out performers” who lost more weight than others. Some women lost more than 30 pounds, while some others actually gained about 10 pounds, a result also experienced by many dieters “in real life”. This wide swing is common in weight loss studies of this sort, but is masked by the averaging of the weight loss within each group. Some people do really well, some people do OK, and others are miserable. Often, the difference is attributed to the moral failings of the participants in adhering to the diet.

Is something else afoot? Presented with conflicting evidence, you have two choices: ignore it or study it. Dr. Gardner studied it.

In a study involving 133 overweight women, those with a genetic predisposition to benefit from a low-carbohydrate diet lost 2 1/2 times as much weight as those on the same diet without the predisposition. Similarly, women with a genetic makeup that favored a low-fat diet lost substantially more weight than women who curbed fat calories without low-fat genes. The women were followed for a year.

“Knowing your genotype for low-carb or low-fat diets could help you increase your weight-loss success,” said Christopher Gardner, an associate professor of medicine at Stanford and a co-author of the study.

From the Wall Street Journal, March 4, 2010 (subscription may be required).

The study was presented at the American Heart Association’s annual epidemiology and prevention conference in March, 2010, and has been submitted to a medical journal for publishing. Peer review guidelines require a period of review before the actual study is published.

Dr. Gardner commented:

“The differentiation in weight loss for individuals who followed a diet matched to their genotype versus one that was not matched to their genotype is highly significant and represents an approach to weight loss that has not previously been reported in literature.”

He added that using genetic information would “be important in helping to solve the pervasive problem of excessive weight in our society”.

The Wall Street Journal article includes some more information on the participants: they were a subset of the 311 women who participated in the A to Z Weight Loss Study. Testing in other studies reveals that 45% of white women have a “low carb genotype” while 39% have a “low fat genotype”. Interleukin Genetics developed the genetic test used to determine the participant’s genetic suitability for either a low fat or low carb diet.

Edit March 7, 2011: a good review of the study is at Dr. Fabricio Gonzalez’s Blog, with some detail and his reservations about the study. His first reservation, that the sample size was small, doesn’t seem like a major objection to me; over 100 participants in a follow up study, comparing their known results from a past test, seems authoritative enough for me.

I still have not been able to find a copy of the actual study that is available without paying.

How Carbs Influence LDL

One of the fears some have in adopting a low carb diet is the possibility that LDL cholesterol will increase. And indeed, in the typical blood test we take, there is sometimes an increase in this so-called bad cholesterol. But what is the real relationship between carb consumption and LDL particles in the bloodstream?

Dr. William Davis of the Heart Scan Blog has some clarification for us:

Carbohydrates:
1) Increase triglycerides and very low-density lipoprotein particles (VLDL)
2) Triglyceride-rich VLDL interact with LDL particles, making them smaller. (A process mediated by several enzymes, such as cholesteryl-ester transfer protein.)
3) Smaller LDL particles are more oxidizable–Oxidized LDL particles are the sort that are taken up by inflammatory white blood cells residing in the artery wall and atherosclerotic plaque.
4) Smaller LDL particles are more glycatable–Glycation of LDL is an important phenomenon that makes the LDL particle more atherogenic (plaque-causing). Glycated LDLs are not recognized by the LDL receptor, causing them to persist in the bloodstream longer than non-glcyated LDL. Glycated LDL is therefore taken up by inflammatory white blood cells in plaque.

Of course, carbohydrates also make you fat, further fueling the fire of this sequence.

Dr. Davis’ main concern is the impact eating carbs has on your cardiovascular health … not fat, but carbs. He focuses on the most recent scientific evidence and techniques to shepherd his patients past heart disease and toward longer, healthier lives. Is he concerned that the standard blood test may show a rise in LDL cholesterol? Not at all.

The standard blood test uses the Friedewald calculation rather than measuring the blood lipids directly. We have several articles on LDL and the Friedewald calculation for your edification.

Low Carb Gaining Ground

Research continues to pile up that validates a low carb diet for weight loss in adults without jeopardizing health. Now comes a study revealing that it may be a solution for obese teens as well:

To investigate, the researchers randomly assigned 24 severely obese teenagers to eat a high-protein, low-carbohydrate diet and 22 matched teens to eat a low-fat diet for 13 weeks. The study subjects were 14 years old on average and were at least 175 percent above ideal weight, but were free of type 2 diabetes or other serious medical problems. They were closely supervised throughout the study.

On average, those on the high-protein, low-carb diet lost 29 pounds over 13 weeks, while those on the low-fat diet lost 16 pounds. Both groups kept the weight off nine months after the study. “We had expected the high-protein, low-carbohydrate group to quickly regain all the weight lost, but this did not occur,” Krebs said. “At the end of the day, this suggests that with ongoing support, these patients could perhaps have achieved even more weight loss.”

The high-fat, low-carbohydrate diet also appeared to be safe, with no serious harmful effects on growth, bone mineral density, and various “metabolic” parameters, such as cholesterol levels. Both groups showed declines in levels of harmful LDL cholesterol and increases in levels of heart-healthy HDL cholesterol.

The study was headed by Dr. Dr. Nancy F. Krebs, professor of pediatrics and head of the division of pediatric nutrition at the University of Colorado Denver School of Medicine. Dr. Krebs notes that concerns about the impact of a low carb, high fat diet on teens has kept physicians from using the diet for underage patients. The results of this study showed that under medical supervision, extremely obese teen-aged patients can try a low carb diet for weight loss.