Archive for November, 2009

Low carb diet wins again

November 21st, 2009

A few days ago I posted a more recent study by Chris Gardner comparing various popular diets. It was a big study and done very well, but it was based strictly on self reporting. Ideally all the subjects should live in a metabolic ward and be monitored 24 hours a day and fed exactly the right amount. But as you can imagine, that would be extremely expensive. A more affordable way to check for low-carb diet adherence can be found in your toilet.

When someone goes on a very low carb diet, their liver produces something called ketone bodies which can provide energy in place of the depleted glucose source from your diet. Ketones can be detected in the urine (called ketonuria) and therefore provide a reliable way to ensure that someone is following a low carbohydrate diet.

In a study published in Nutrition and Metabolism in 2004, researchers compared an energy restricted low carbohydrate diet to an energy restricted low fat diet monitoring ketonuria every day to make sure the low carb dieters were not cheating. The low carb diet was supposed to eat less than 10% of their diet from carbohydrates and the low fat diet was supposed to follow the national recommendations (%carb:fat:protein = 60:25:15).

Since there is a lot of variation in response to diet, the researchers also decided to compare each persons response to both diets. This is called a crossover trial. This approach allows them to compare the diets in 2 ways: between groups, and within each group between the individuals of that group. They then did further analysis to see if the order of each diet mattered.

Each group was given a detailed list of what foods they could eat and ordered to keep a food diary, and their urine was tested each day for ketonuria.

The men followed the diet for 50 days and women for 30. Between groups, men lost more weight and fat. Within groups when each individual was in their low carb phase of the diet, both men and women lost more weight and fat as well when compared to the low fat phase. All this despite the low carb group eating reportedly more calories!! (1855/day vs 1562/day in the low fat group).

Comparing Men and Women results between groups

Despite this being a short term study involving only about 30 people, i think it provides powerful support for the efficacy of a low carb diet for weight and fat loss. The researchers took every precaution possible to make sure that the low carbohydrate group stuck to their diet. The fact that they reported eating more calories per day is also astounding. One can claim the low carb group inaccurately reported their calorie consumption. But without any evidence that this is true, you cannot assume that their reporting was any less accurate than the low fat group.

These results also beg the question: is a calorie actually just a calorie? Most nutritionists will tell you a calorie is a calorie and you cannot disobey the 1st law of thermodynamics, but this study (along with many others to come in the future) beg to differ.

Nutrition and Weight Loss

“Healthy” Government Recommended Diet May Not Be So Beneficial After All

November 20th, 2009

From the USDA Dietary Reccomendations for Americans:


  • Consume a sufficient amount of fruits and vegetables while staying within energy needs.
  • Choose a variety of fruits and vegetables each day. In particular, select from all five vegetable subgroups (dark green, orange, legumes, starchy vegetables, and other vegetables) several times a week.
  • Consume 3 or more ounce-equivalents of whole-grain products per day.
  • Consume 3 cups per day of fat-free or low-fat milk or equivalent milk products.


  • Consume less than 10 percent of calories from saturated fatty acids and less than 300 mg/day of cholesterol, and keep trans fatty acid consumption as low as possible.
  • Keep total fat intake between 20 to 35 percent of calories, with most fats coming from sources of polyunsaturated and monounsaturated fatty acids, such as fish, nuts, and vegetable oils.
  • When selecting and preparing meat, poultry, dry beans, and milk or milk products, make choices that are lean, low-fat, or fat-free.
  • Limit intake of fats and oils high in saturated and/or trans fatty acids, and choose products low in such fats and oils.

The above is an excerpt from the most recent government recommendations for what to eat to “promote health and reduce risk for major chronic diseases.” I don’t think many people in America would disagree with these recommendations. It is common knowledge now a days, but is it true? Does following these guidelines lead to a healthier life? The government funded what they claimed to be “the largest long-term randomized trial of a dietary intervention ever conducted” to find out.

It was called the Women’s Health Initiative, monitoring about 49,000 women for over 8 years. They looked for changes in weight, changes in risk of cardiovascular disease, and changes in risk of colorectal cancer.

Women were randomly assigned to a control group, receiving some nutrition information and a copy of the dietary guidelines, and the intervention group, which had a series of group meetings educating them on what to eat and encouraging them to reduce their dietary fat to 20% of their diet, increasing their fruit and vegetable intake to 5 or more servings per day, and 6 or more servings of grains. The nutrients consumed in each group were monitored throughout the study, and the intervention group did in fact significantly decrease their fat intake and increase their fruits, vegetables and grains.

After about 8 years, there was no decrease in risk of developing colorectal cancer, coronary artery disease, stroke, or cardiovascular disease, and no significant change in weight (the study was not designed for weight loss).


Weight changes

Differences in Colorectal Cancer between the two groups

Differences in Colorectal Cancer between the two groups

Changes in risk of having various cardiovascular complications

Changes in risk of having various cardiovascular complication

The organization who funded this study posted a response here. The director of the National Heart, Lung, and Blood Institute, Elizabeth G. Nabel, M.D., states “the results of this study do not change established recommendations on disease prevention.” It is definitely true that recommendations should not be changed based on one study, but if the largest long term study ever done on dietary intake does not confirm the current recommendations then maybe, just maybe, there is a possibility that the recommendations are incorrect.

The results of this study, as well as most dietary studies, rely on self reporting. People notoriously under report how much they eat, forget what they eat, or lie about what they eat. All that we can assume is that they all under report and lie to the same degree and therefore trends can be established.  One can claim that this study cannot change the established recommendations and should not be taken as fact because it is not a randomized control trial. Very true. But if the results confirmed the current recommendations, would these same study design criticisms be made?

Nutrition and Weight Loss

Comparing effectiveness and health of the most popular diets

November 17th, 2009

The million dollar question everybody wishes to know: Which diet should I go on?

Chris Gardner, a Ph.D in nutrition science and a professor at Stanford Medical School, tried to find this out, at least in obese, pre-menopausal women. In a study published in 2007, 311 women were randomized to consume 1 of 4 diets:

The Atkins group was instructed to eat 20 grams of carbs a day for the first 2 months, and 50 grams each day there after

The Zone diet group members followed a 40%-30%-30% distribution of protein carbs and fat respectively.

The Ornish group were advised to consume no more than 10% of calories from fat, no specific calorie amount specified.

The LEARN group consumed a diet 55-60% from carbohydrates and less than 10% energy from saturated fat. This is a diet similar to the government recommended dietary guidelines.

Every group was required to attend a weekly educational session for the first 8 weeks on their diet followed by 10 months without the help of a dietitian. After a year on their respective diets, the results were striking:

People following the Atkins diet lost more weight (mean weight loss of 4.7kg or 10.3 lbs) compared to 1.6 kg from Zone, 2.2kg from LEARN, and 2.6 kg for Ornish. The weight loss obtained via Atkins diet was significantly different from the the other diet groups, and there was no significant differences among Zone, LEARN or Ornish at any time during the study.

Weight loss on various diets over time

Weight loss on various diets over time

As you can see in the figure, at 2, 6, and 12 months the Atkins diet resulted in the most weight loss.

I know what you are thinking: maybe they lost more weight but they’re good cholesterol (HDL) must have gone down, and their bad cholesterol (LDL) and their Triglycerides must be off the charts with all that saturated fat these people are eating. At least this is what I would have thought a year ago.

During the entire study no group did better than the Atkins diet for any metabolic risk factor that was measured. Atkins trumped every other diet in blood pressure, HDL levels and  triglycerides. There was no difference in LDL among the groups.

When Chris Gardner presents these findings in the video above, he calls them “a bitter pill to swallow” for a 20+ year vegetarian. These findings go against everything we have been saying for the past 30 years. Could these results possibly be right!?

In this clinical trial (as well as many others I will post on this blog in the future) comparing low carb to low fat diets, it seems that every time almost without fail the low carbohydrate group seems to be more successful in losing weight, decreasing triglycerides and increasing HDL.

Critics of this study will say that all the dietary intake was done through unreliable self reporting, and everyone under reports their calories. Both are valid criticisms, but if study after study comes up with the same basic conclusion, than maybe there is some merit to them. Maybe a low carbohydrate is a very effective way to lose weight and improve your health.

Nutrition and Weight Loss


November 11th, 2009

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In an effort to offer up to date advice on current research in the fields of nutrition and weight control, our nutrition expert will maintain a blog at updated daily which keeps you informed of the current studies being done as well as a summary of the major findings. This blog can be easily accessed through our PhotoCalorie iPhone application.

Our goal is to provide information and advice based strictly on current findings in scientific literature, and NOT on advice from “Diet Guru’s” who claim to posses the secrets to health and wellness.