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.

3 comments:

  1. Were the Omega-3 supplements fish oil or ALA based, which would make a difference. In any event, are these really marketed as weight loss aids? That's not something I see being done.

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  2. Wouldn't the fact that we're eating almost 200 calories more per day be the message? That's about a pound every two weeks, without offsetting activity. Where is it coming from? More fast food, junk food? Can we completely fault high complex carbs in this?

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  3. Thanks for the comments Larry,
    1) The omega 3 supplements were fish oil based. The participants were given 5 capsules daily, each of which contained 3.0 grams of EPA + DHA at a 5:1 ratio in a 60% concentration composed of 2258 mg fish oil concentrate and 1400 mg omega 3 fatty acids. Although omega 3's aren't specifically marketed as weight loss aids, there has been a lot of interest in this recently due to several animal studies that suggested an increased body fat oxidation and energy expenditure as well as appetite suppressing effects of omega 3 supplementation.

    2) The fact that we are eating 200 more calories per day is the message. However, it is very likely that the reason we are eating more is due to the reactive hypoglycemia that comes with lower fat intakes and increases in high glycemic carbohydrate consumption. With greater carb and lower fat intakes, the resulting higher insulin levels drive blood sugar below fasting levels which can significantly increase hunger and subsequent energy intake.

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