Monday, August 29, 2011

Research Update: Macronutrient Trends In The U.S. And Omega 3's Impact On Weight Loss

Trends in carbohydrate, fat and protein intakes and association with energy intake in normal weight, overweight and obese individuals: 1971-2006.
American Journal of Clinical Nutrition 2011; 92:836-43.

This study looked at the changes in fat, protein and carbohydrate consumption in the U.S. between the years of 1971 and 2006.  The two population samples compared were the NHANES in 1971 and the NHANES in 2006.  NHANES stands for National Health And Nutrition Examination Survey.  It is a large study conducted every 2 years to examine the health and nutrition status of non-institutionalized U.S. civilian adults and children.  Physical exams were performed in mobile units and diet was assessed by means of 24 hours dietary recalls.

The results were striking. Between 1971 and 2006 the prevalence of obesity in men increased from 11.9% to 33.4%.  In women, obesity increased from 16.6% to 36.5%.  During this time, carbohydrate consumption increased from 44% of calories to 48.7%.  Fat consumption decreased from 36.6% to 33.7%.  Protein consumption decreased from 16.5% to 15.7%.  During this period the typical man consumed an additional 179 calories per day and women consumed an additional 199 calories per day.

Take Home Message:  This study tells us 2 things: #1) As a country, we’ve bought into the whole low fat, high carb message over the past few decades.  #2) It’s not working.  As carbs go up and fat goes down, we are eating more calories and gaining more weight.   Many government and health agencies are still promoting low fat, high carb diets as a weight management strategy.  It’s time for a fundamental change in this philosophy.

Effects of omega-3 supplementation in combination with diet and exercise on weight loss and body composition.
American Journal of Clinical Nutrition 2011; 93:455-62.

The goal of this study was to determine if omega-3 supplementation can enhance weight loss when combined with diet and exercise.  Subjects were randomized to two groups.  64 subjects received 15 grams of omega-3 supplements per day with an EPA:DHA ratio of 5 to 1.  The other group of 64 received placebo pills.  Both groups received diet advice as well as resistance training and cardiovascular exercise programs.  After 6 months, the total amount of weight lost was compared.  Both groups lost greater than 5% of their initial body weight.  There was no difference in weight loss between the two groups.

Take Home Message: Despite preliminary research in animals suggesting that omega-3 supplements enhanced weight loss, it doesn’t look like it will do much in humans.  Add omega 3 to the large and forever growing list of weight loss supplements that don’t really work.

Monday, August 15, 2011

Book Review: The Dukan Diet

           The Dukan Diet is next up for review.  The author, Dr. Pierre Dukan, is a French Medical Doctor that has been specializing in human nutrition since 1973.  This book was a blockbuster in Europe and the fact that Prince William’s bride used it to get ready for her wedding did not hurt sales! From a nutritional standpoint, this book has received a lot of criticism. 

            The diet is composed of 4 phases.  The first 2 phases are supposed to help you lose weight and the last 2 help keep it off.  Phase 1 is called the Attack Phase and consists of eating nothing but pure protein, not an ounce of fat or carbohydrate.  This phase lasts for about a week.  Phase 2 is called the Cruise Phase and consists of alternating pure protein days with protein plus low carb vegetable days.  You stay on this phase until you hit your goal weight.  Phase 3 is called the Consolidation Phase and during this phase you can eat all the protein and Phase 2 vegetables you want, 2 slices of whole wheat bread, a portion of fruit and cheese, 2 starchy carbs and 2 celebration meals per week.  You stay in this phase 5 days for every pound lost.   Phase 4 is the Permanent Phase.  Here you can eat exactly as you did on Phase 3 but you must add a pure protein day every Thursday, a 20 minute walk each day, 3 daily tablespoons of oat bran and you must pledge to use no elevators or escalators.  Overall the book was well written and an easy read.  It translates well from its native French to English.
5 Things I Liked About The Dukan Diet
1) Dukan is strongly against refined carbohydrate foods.  I couldn’t agree more.

2) From Phrase 3 on, the program includes 2 cheat meals.  I have found this to be extremely helpful for my weight loss clients.  You don’t need to be 100% with your diet to hit your weight loss goals and it’s not realistic to never eat for fun.

3) Exercise gets a fair amount of attention and this is quite rare for diet books.

4) The recipe chapter in the book details some creative ways to eat low carb. 

5) His theory that humans are biologically designed to be meat eaters is right on.

What I didn’t agree with in The Dukan Diet
1) The majority of the phases of this program are nutritionally unbalanced.  Extremely healthy categories of foods are eliminated or strictly limited for the majority of this dietary plan.  Examples include: vegetable oils, nuts, fruits, many vegetables, whole grains and legumes, among others.

2) It is a bit heavy on the red meat.  Steak, bacon, hot dogs, etc are allowed in unlimited quantities.  This is not a good idea.  Cooking red meat forms carcinogenic heterocyclic amines, which have the potential to increase risk of colon and other digestive cancers.  This is made worse by his recommendation to overcook red meat in order to reduce the fat content.  The more you cook red meat, the higher the formation of heterocyclic amines and the higher the carcinogenic potential.

3) Advocates taking a diuretic when you hit a tough weight loss plateau.  I had to read that one again to make sure I got it right.

4) Made some very interesting and very unscientific claims throughout the book.  Here’s an example:
            -Sucking on 5 ice cubes per day will burn off 6 pounds of fat in a year.
            -A 2 minute cold shower burns as many calories as walking 2 miles.
            -The combination of water and dietary protein melts cellulite.

5) Advocates drinking as much diet soda as you want throughout the program.  Dukan mentions that it reduces cravings for carbs.  Both current research and my experience with clients have taught me that diet soda has the potential to increase cravings for refined carbs, not decrease them.

Is The Dukan Diet Worth Reading?
Absolutely.  If you are interested in nutrition as a profession or for your own personal health, read as many books as you can.   I think it is important to get as many different perspectives as possible.  Will this diet work short term? I’m sure it will, it has sold a lot of books for a good reason.  Will it work for the long term? Unlikely. The literature shows us that most can’t stay on restrictive low carb diets for very long.  Is it a healthy way to eat?  In my opinion, no.  You are strictly limiting foods we know are healthy for you and eating a lot of foods that are not.