Low Carb vs. Low Fat for Weight Loss

Apparently, 14 clinical trials comparing a low carb diets with low fat diets with statistically significant results have been published between 2003 and 2008. In all 14 trials, those on low carb diets lost significantly more weight than those on low fat diets. The author is careful to point out that he only selected studies that statistically compared one diet to another, and that the "low carb" diets were truly low carb. (Some studies claiming to compare low fat with "low carb" are not really low carb, as there are more than 30% of calories from carbohydrates. In a true low carb diet, carbs are usually 5 to 10% of calories).

The author of the article summarizing this list has given permission to copy it onto other blogs, so I am taking advantage of his generosity. Here are the studies, complete with links, for you data junkies out there.


Randomized controlled trials showing significantly more weight loss with low carb diets:

• Brehm BJ, et al. A Randomized Trial Comparing a Very Low Carbohydrate Diet and a Calorie-Restricted Low Fat Diet on Body Weight and Cardiovascular Risk Factors in Healthy Women. J Clin Endocrinol Metab 2003;88:1617–1623.
• Samaha FF, et al. A Low-Carbohydrate as Compared with a Low-Fat Diet in Severe Obesity. N Engl J Med 2003;348:2074–81.
• Sondike SB, et al. Effects of a low-carbohydrate diet on weight loss and cardiovascular risk factor in overweight adolescents. J Pediatr. 2003 Mar;142(3):253–8.
• Aude YW, et al. The National Cholesterol Education Program Diet vs a Diet Lower in Carbohydrates and Higher in Protein and Monounsaturated Fat. A Randomized Trial. Arch Intern Med. 2004;164:2141–2146.
• Volek JS, et al. Comparison of energy-restricted very low-carbohydrate and low-fat diets on weight loss and body composition in overweight men and women. Nutrition & Metabolism 2004, 1:13.
• Yancy WS Jr, et al. A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and Hyperlipidemia. A Randomized, Controlled Trial. Ann Intern Med. 2004;140:769–777.
• Nichols-Richardsson SM, et al. Perceived Hunger Is Lower and Weight Loss Is Greater in Overweight Premenopausal Women Consuming a Low-Carbohydrate/High- Protein vs High-Carbohydrate/Low-Fat Diet. J Am Diet Assoc. 2005;105:1433–1437.
• Gardner CD, et al. Comparison of the Atkins, Zone, Ornish, and learn Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women. The a to z Weight Loss Study: A Randomized Trial. JAMA. 2007;297:969–977.
• Shai I, et al. Weight loss with a low-carbohydrate, mediterranean, or low-fat diet. N Engl J Med 2008;359(3);229–41.
• Krebs NF, et al. Efficacy and Safety of a High Protein, Low Carbohydrate Diet for Weight Loss in Severely Obese Adolescents. J Pediatr 2010;157:252-8.
• Summer SS, et al. Adiponectin Changes in Relation to the Macronutrient Composition of a Weight-Loss Diet. Obesity (Silver Spring). 2011 Mar 31. [Epub ahead of print]
• Daly ME, et al. Short-term effects of severe dietary carbohydrate-restriction advice in Type 2 diabetes–a randomized controlled trial. Diabet Med. 2006 Jan;23(1):15–20.
• Westman EC, et al. The effect of a low-carbohydrate, ketogenic diet versus a low- glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutr. Metab (Lond.)2008 Dec 19;5:36.
• Dyson PA, et al. A low-carbohydrate diet is more effective in reducing body weight than healthy eating in both diabetic and non-diabetic subjects. Diabet Med. 2007 Dec;24(12):1430-5.

Misc. Thoughts, Studies, and Blog Posts

No updates this week, as I am traveling and away from home, where I weigh myself. However, I can feel my pants getting looser by the day, so I am confident I have lost weight. Below are some jumbled thoughts and ramblings from my surfing throughout the low carb blogosphere.

I have received two books in the mail from Amazon.com that I am currently reading: Nourishing Traditions by Sally Fallon and Mary Enig and The Art and Science of Low Carbohydrate Living by Stephen Phinney and Jeff Volek. I haven't had time to read them yet, but will report on them when I do. The first one, Nourishing Traditions, is actually a cookbook which explains the philosophy behind the Weston A. Price Foundation's view on achieving perfect health. As I have flipped through it, it looks very interesting and unlike other cookbooks I have referenced. The second book is a How To book, which explains the ins and outs of the low carb lifestyle. It is targeted towards health professionals.

In news from around the low carb blogosphere, Chris Kresser of the Healthy Skeptic has a new post on natural childbirth. My daughter has been educating me on natural childbirth (I've commented on the topic before), and I find it interesting that a man has written on the topic. His wife makes several comments about the topic (e.g., here, here, and here) in the comments section and he is fully supportive of the procedure. In fact, it seems logical, given his focus on natural health and the paleo diet.

Denise Minger of the Raw Foods SOS blog tweeted about a study showing a link between antidepressant drugs (e.g., Prozac, Zoloft, Paxil, Celexa) and the occurrence of autism. Caution: this is an observational study which shows correlation, not causation. Nevertheless, it is an interesting hypothesis that warrants further study.

Tom Naughton of the Fathead blog writes that most vegetarians become ex-vegetarians. He reviews a news article on the subject and makes some interesting conclusions. People who chose vegetarianism for ethical reasons are now eating meat (prepared in an ethical manner, e.g., grass fed, not feedlot meat). Poor health from the vegetarian diet is the number one reason people go back to eating meat.

A recent rodent study showed that a low carb diet helps prevent weight gain, cancer development and progression, and tumor growth.

Another study shows that fake fat (like Olestra) causes more weight gain than real fat. It was fun watching the authors spin the results of this study!

Low Fat Diet Harms Women with Diabetes by Raising Blood Sugars

There is no media frenzy about this study, but a new study on real women (not rats or monkeys) showed that post-menopausal women with diabetes who ate a low fat diet suffered significant harm. Read the scientific abstract, as well as a discussion of the results by Jenny Ruhl of the Diabetes Update blog. Basically, the low fat, high carbohydrate diet caused very large swings in the blood sugar readings of diabetic women.

When you cut the fat out of your diet, you have to replace it with either carbohydrates or protein. And since carbohydrates drive up blood sugar readings, this is what happens when you replace the fat in your diet with carbs. Fat has very little effect on blood sugar readings, so when you replace the carbs in your diet with fat, not only is your hunger sated, your blood sugars improve.

We already know from a study of nearly 50,000 post-menopausal women that a low fat diet offers very little protection against coronary heart disease, stroke, or cardiovascular disease. Now we learn that a low fat diet actually harms this same group of women if they are already diabetic.

Shaving, Heart Disease, and Observational Studies

Do men who shave daily have fewer heart attacks than those who only shave once every two or three days? This is the finding of at least one study. However, Michael R. Eades, M.D. uses this example to show people the difference between observational scientific studies that generate hypotheses and causal scientific studies that generate reproducible scientific facts.

The shaving study is an example of an observational study. When you dig deeper, as Eades does, you see that it is not shaving which is linked to fewer heart attacks, but the attributes of men who shave more often that lead to fewer heart attacks. So, says he, correlation is not causation. This is a great lesson to remember, the next time a scientific study du jour is released that makes some claim. If it was an observational study, it merely generated an hypothesis, which needs further testing.

Moderate Carb Reduction and Weight Loss

A moderate reduction in carbs leads to reduced total body fat, according to a recent study. I should point out that the "low carb" diet used in this study is hardly low carb at all, with 43% of calories coming from carbs. On a true low carb diet, only about 10 to 15% of calories will come from carbs. My very low carb diet is perhaps 5%. But even still, a modest reduction from 55% of consumed calories from carbs down to 43% led to deep fat loss in the subjects. Why? Because rapidly digested carbs are fattening.

Eating a High Fat Diet and Staying Lean

The results of a recent study show that a low carb diet (high fat, medium protein, low carb) plus exercise helps people to lose weight quicker than a low fat diet.  Vascular health was also monitored, and there were no negative impact on vascular health reported with either diet.  The trial was short, so the authors put in a boiler plate mention that the long term effects are "yet to be determined." Other research has demonstrated the safety of the low carb diet over the longer term.

Eating Dirt

So, can eating dirt help cure depression?  I don't know, but there is an intriguing article about "germophobic helicopter parent[s]" obsessed with cleanliness and the impact that has on depression. I don't really know what to think about this article, but it was fascinating to read. Basically, it boils down to the argument that we co-evolved with certain parasites, which we have essentially eliminated from our diet by being cleaner than our evolutionary ancestors.

By the way, I loved the photo of the little girl eating a mouthful of dirt (scroll down to the end of the article to see the photo).

Low Carb Diets and High Blood Pressure

Apparently, one in five adults between the ages of 24 and 32 have high blood pressure, due to expanding waist lines.  This is a problem, because most young adults don't see a physician regularly and are probably not aware they have high blood pressure.The article suggests cutting salt as a way to reduce blood pressure, but we also know that the fear of salt is almost as overblown as the fear of fat so that is a pretty useless suggestion.

If you want to lower your blood pressure, why not try a low carb diet?  My high blood pressure normalized within two weeks of starting my low carb lifestyle, and empirical research shows low carb diets are very effective at lowering blood pressure (here is the actual journal article).  You will have dramatically lower blood pressure results a lot more quickly than cutting your salt intake.

Research Update

Want to increase your odds of getting Alzheimer's disease?  Then eat a high carb diet. Of course, as I have mentioned before, Alzheimer's disease is sometimes called type III diabetes, and the best way to deal with diabetes is a low carb diet, combined with exercise, drugs, and insulin, where necessary. Thus, it makes sense that a low carb diet will help to prevent Alzheimer's disease.

This article follows 13 to 15 year old girls who exercise, and concludes that exercise increases causes these girls to work up an appetite and to eat more. As we have mentioned before, there are many good reasons to exercise, but exercising in an effort to lose weight is not one of them because people work up an appetite and eat more.  In fact, just thinking about exercise causes people to eat more.

Hat tip: Michael R. Eades' twitter page.

For the Science Behind Low Carb Lifestyles

If you are in to the science behind the low carb lifestyle, there are some great blogs out there.  They are dense, and it helps a lot to understand multivariate statistics.  I wouldn't recommend these links for the casual reader, but if science is your thing, read on.

• HyperLipid--If you want to know about dietary fat, this is the site for you.  Written by Petro "Peter" Dombromylskyj, a veterinarian and deep thinker about all things fat related.
• Whole Health Source--The science behind the primal or paleo movement.  Written by Stephen Guyenet, a Ph.D. in neurobiology.
• Perfect Health Diet--The science behind what the authors believe to be the perfect diet for health.  Written by Paul Jaminet, a Ph.D. in astrophysics and his wife, Shou Ching-Shih Jaminet, a Ph.D. in molecular biology.  They discovered the low carb lifestyle in 2005 and have been studying it ever since. Plus, great recipes.
• Cholesterol and Health--The science behind the cholesterol debate.  Written by Chris Masterjohn, a Ph.D. candidate in nutrition at the University of Connecticut.  His blog is linked to this site.

There are others, but in my opinion, these are the heavy weights.  Again, not for everyone, but if you like the scientific discussion behind nutrition, you will love these blogs.

Great Blog on the Science Behind Low Carbing

I recently stumbled across a great blog on the science behind the low carb lifestyle.  It is called Low Carb For You and it is written by a Ph.D. in medical biochemistry.  If you are interested in the science behind the low carb lifestyle, I would highly recommend this blog.  I have added it to my list of blogs so you can always find a link from this site.

Research Update

In addition to the usual results showing low carb dieters losing more weight, achieving better blood glucose levels, and losing more inches than low fat, high carb dieters, this new study also demonstrated that low carb dieters had better memory performance.  Ketone levels were significantly and positively correlated with memory performance, but low fat, high carb dieters don't achieve ketosis, so they are out of luck.  This is important, because low carb diets are very good for type II diabetics.  Type II diabetics are at a greater risk of developing Alzheimer's disease, which is sometimes called "type III diabetes."  "Type III" diabetes would certainly affect your memory performance.

Another study showed that in adults afflicted with non-alcoholic fatty liver disease (about 1/3 of the adult population in the U.S.) lost significantly more liver fat after two weeks on a low carb diet than on a low fat, high carb diet.  Weight loss after two weeks was about the same on both regimes, but loss of liver fat was the key goal of the study, and the low carb diet proved better.

More interesting food articles from the marketing journal, The Journal of Consumer Research.  I find it fascinating that the academic marketing discipline is so focused on eating.

• Consumers are more likely to order more calories at a restaurant they perceive as "healthy," such as Subway, than at a restaurant they perceive as "unhealthy," such as McDonald's (this link opens a press release in an MS Word document).  There is a "health halo" associated with "healthy" restaurants, such as Subway.  Since consumers tell themselves they are eating healthy, they splurge on unhealthy sides, drinks, and desserts.  When they eat at a restaurant perceived as "unhealthy," they are more aware of what they are eating and actually consume fewer calories than at "healthy" restaurants.  Stupid dieters.
• When consumers face their own mortality, such as immediately after the 9/11 attacks, they eat more, drink more, and want to spend more time with their families (this link opens a press release in an MS Word document).
• The color of orange juice made people think it was sweeter.  Researchers wanted subjects to choose the "sweetest" orange juice (this link opens a press release in an MS Word document).  The subjects perceived no difference when one cup had a lot of sugar added and the other didn't, but they perceived a huge difference in sweetness when the orange juice was brighter, thanks to food dye.  Eyesight trumped the taste buds!

Interesting Marketing Articles

I am a marketing professor (yes, a dreaded Ph.D.) and, surprisingly, there are a lot of food related studies appearing in the Journal of Consumer Research, a major marketing journal, that are relevant to the theme of this blog.

In one study, dieters are more cranky than non-dieters (because, in my opinion, they are starving on a high carb, low fat diet).  The study appeared in the Journal of Consumer Research; here is an online report summarizing the findings.  If you use a computer on a university campus, you will likely be able to access the original article.  If not, read the summary.  I'd be cranky, too, on a low-fat, high carb diet.

Do names matter?  Another study in the Journal of Consumer Research shows that when a food is labeled by a name perceived to be unhealthy (e.g., pasta), dieters perceive the item to be more unhealthy than non-dieters.  But when the same food is identified by a healthy name (e.g., salad), dieters and non-dieters alike make no product evaluations.

Yet another study in The Journal of Consumer Research shows that junk food is impulsively purchased, and the shoppers who pay by credit card are much more likely to purchase junk food than shoppers who pay with cash.  One thousand households were observed over a six month period and the researchers concluded that credit card purchases are relatively painless, whereas separating with cold hard cash is not.  Of course, the nannies in the study now want us all to pay for junk food with cash.  Why not just avoid it?

For whatever reason, there are a large number of food studies in JCR.  I will report on more later.

Fruits and Vegetables

I keep learning that I have been misled in life, nutritionally speaking.  Are fruits and vegetables the wonder foods they are made out to be?  I do eat veggies, especially leafy and green vegetables, and occasionally I eat raspberries.  But three recent studies have opened my eyes to the so-called benefits of a diet high in fruits and vegetables.

One study concluded that a diet high in fruits, vegetables and grains (and low in fat) did not significantly reduce the risks of coronary heart disease, stroke, or cardiovascular disease in post menopausal women over the eight years of the study.

Another study concluded that a low fat, high fiber diet with a lot of fruits and vegetables had no significant effects staving off a second bout of breast cancer in women who already beaten breast cancer once.  This was a 7.3 year long study.

A third study failed to find any beneficial effects of a low fat, high fiber, high fruits and vegetables diet on recurrence of bowel cancer in victims who had already suffered from this cancer, even after eight years.

So, where are the studies that show beneficial effects of a low fat, high fiber, high fruit and vegetable diet?  I haven't yet found any.  That doesn't mean they don't exist, but it is quite easy to find studies that show no beneficial effects and I have not had such an easy time locating the studies with empirical results demonstrating the benefits of a diet high in fruits and vegetables (and low in fat).

Interesting Research Articles

As I continue on my journey, I am discovering more and more scientific literature with conclusions that are startling.  Why did I not know this information before?  Nutritional public policy is way behind the times.  I spent a bit of time on the Metabolism Society web site and discovered many scientific studies on the impact of the LCD on cardiovascular disease, type II diabetes, obesity, cancer, etc.  Below are a few gems I found from this site.

Saturated Fat and Cardiovascular Disease.  A meta-analysis of 348,000 subjects over 5 to 23 years leads to this conclusion:  "[T]here is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD [coronary heart disease] or CVD [cardiovascular disease]."

Are Refined Carbohydrates Worse than Saturated Fat?  This article still believes saturated fats are bad, but it also concludes that replacing fat in the diet with refined carbohydrates is bad, too, and suggests adding more sources of vegetable fat and consuming non-refined carbs and lean protein.  It reports on a large scale study on the affects of saturated fat on myocardial infarction (MI; heart attacks) and concludes that "saturated fat intake was not associated with risk of MI compared with carbohydrate consumption" but that replacing saturated fat with refined carbs "significantly increased the risk of MI."

Low Carb Diets and Cardiovascular Disease.  Conclusion:  "A diet based on restricting carbohydrates leads to spontaneous caloric reduction and subsequent improvement in emerging markers of CVD [cardiovascular disease] in overweight/obese men who are otherwise healthy."

The Effect of a Low Carb Diet on People with Severe Type II Diabetes.  Conclusion:  "The 30% carbohydrate diet over 6 months led to a remarkable reduction in HbA1c levels, even among outpatients with severe type 2 diabetes, without any insulin therapy, hospital care, or increase in sulfonylureas.  The effectiveness of the diet may be comparable to that of insulin therapy."

High Fructose Corn Syrup

In his book, Why We Get Fat, Gary Taubes discusses the uniquely fattening properties of sugars, especially high fructose corn syrup.  I am discovering that high fructose corn syrup (HFCS) is in a lot of products: regular soda pop, bread, ketchup, Nyquil (and other cough medicines), doggie treats for my carnivore buddy, Titan (I have stopped buying these for him), Slim Jim beef sticks, not to mention pretty much anything that is sweet.  It is so ubiquitous that it is actually rather hard to avoid.  I have started reading labels very closely.  It even pops up in places I totally don't expect.  Just the other day, I was reading the label on diet Sunkist orange soda, and there it was (the "diet" Sunkist Orange Soda is actually quite caloric).  And I was quite surprised to see it in medicines and cough syrups.  If you are going to cut out carbs from your diet, HFCS should be one of the first to go.

Why is HFCS a problem?  It has been linked to obesity, it fuels the growth of cancerous cells, and it exacerbates type II diabetes by aiding fat deposition and preventing you from feeling full, among other things.

But Won't a Low Carb Diet Give You a Heart Attack?

This is perhaps the most common reaction I get when telling people about the low carb diet (LCD).  The belief that saturated fat will lead to heart attacks is well ingrained in the American psyche.  (It's also illogical.  Obesity leads to heart attacks, so getting lean reduces heart attacks, but a diet designed to make you lean also leads to heart attacks?  You can't have it both ways).  Just because you believe something doesn't make it true.  There has been a fair amount of research recently on the effects of the LCD (see below).

So no, in fact, I won't have a heart attack because of following an LCD.  But I might very well have had one following a traditional high-carb, low fat diet.

Recent studies in major journals all confirm that the LCD improves cardiovascular health.  This blog post by a Ph.D. in medical biochemistry links to and summarizes the results of three major studies appearing in the Annals of Internal Medicine, The New England Journal of Medicine, and The Journal of the American Medical Association.  All show that an LCD lowers risk factors for cardiovascular disease, such as high blood pressure, high blood sugars, and high cholesterol.  Plus click on the review article listed below, which concludes basically the same thing.  The LCD is a heart healthy diet.

A 2007 review article in the American Journal of Clinical Nutrition concluded that LCDs "lead to appetite reduction, weight loss, and improvement in surrogate markers of cardiovascular disease."  Further, it concluded that LCDs improved blood sugar levels in both healthy people and those suffering from type 2 diabetes.