Exploring the sense and nonsense of food and health

The New Diet “Villain”

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A growing number of nutrition “experts” have given up the high fat battle and opted for another villain – the lowly carbohydrate (mainly the refined kind).   Dr. Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health says:

If Americans could eliminate sugary beverages, potatoes, white bread, pasta, white rice and sugar snacks, we would wipe out almost all the problems we have with weight and diabetes and other metabolic diseases.

For years Americans have been told to avoid high fat foods in order to lower their risk of heart disease and look what happened – the nation now has the highest obesity rate in history. And along with this rate came higher diabetes and heart disease risks.   Many people gained weight eating “low-fat” foods that were loaded with sugar and starch.

Most Americans eat about 250-300 grams of carbohydrates a day, which is about 55% of their calorie intake.  The minimum recommendation is about 40% of total calories. The RDA for carbohydrate has been set at 130 grams per day for children and adults. The standard recommendation for carbohydrate is 45-65% of total calories.  This means if 1800 calories are eaten each day, the recommended amount of carbohydrate is 202-292 grams based on 45-65% calories from carbohydrate.

About 25% of adults have metabolic syndrome and cannot handle high loads of carbohydrate in the diet.  You are considered to have this disorder if you have three of the following conditions:

  • High blood triglycerides (over 150 mg)
  • High blood pressure (over 135/85)
  • Central obesity (a waist circumference of greater than 40 (men) and 35 (women).
  • Low HDL (under 40 (men); (under 50 (women)
  • Elevated fasting blood glucose

Dr. Stephen Phinney, a nutritional biochemist and emeritus professor of UC Davis and his colleagues published a study in 2008 that fed 40 overweight or obese men and women with metabolic syndrome one of the following diets for 12 weeks:

  • 1500 calorie, low fat, high carb
  • 1500 calorie, low carb, high fat

The low-fat group consumed about 12 grams of saturated fat out of a total of 40 grams a day while the low-carb group consumed 36 grams of saturated fat out of 40 grams.

At the end of the study, the low carb group had a 50% decrease in triglycerides and a 15% increase in the good HDL.  In the low-fat group, triglycerides decreased only 20% and there was no change in their HDL levels.

Not all nutrition scientists agree with the low carb approach.  Some feel that one food group should not be almost eliminated from the diet whether it is fat or carbohydrate and feel some people go to the extreme.  As some people went overboard on restricting fat a few decades ago, it is feared that some will also do the same with carbohydrate restriction.

I was educated in the low-fat era, but had always heard in my early years that pasta, bread and potatoes were “fattening”.  I feel that in the future genetics will guide our choices as to the best diet for individuals, not groups, i.e. one diet does not fit all.  One thing is becoming clear – that refined carbohydrates are not the best choice – vegetables, and whole fruits (berries, e.g.) and some whole grains have carbohydrates in adequate amounts to keep the balance between the macronutrients reasonable. And as stated in other blog posts, it is important to know your numbers – triglycerides, “good” HDL and “bad” LDL, blood pressure and blood glucose.  These blood values may be a better guide for the best diet for you than weight status.  For some, that may be some degree of carbohydrate restriction.  For others with “normal” metabolism, calorie restriction with a balance in fats, carbohydrates, and protein may be the best option.


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