April 29, 2015

Want to Reach and Maintain a Healthy Weight? Track Glycemic Load, not Calories

If you’re interested in achieving or maintaining a healthy weight, a new study reports that you should be tracking “glycemic load” (GL), not just calories.

Put simply, GL tracks the amount of dietary carbohydrates we consume, as well as the quality of those carbohydrates. 

The study – reported  online in the American Journal of Clinical Nutrition and picked up on April 25 by CBS News – showed that adults gained more weight as the glycemic loads of their diets increased. Specifically, the study revealed that every 50-unit increase in one’s daily GL was associated with gaining one pound every four years.

One pound every four years doesn’t sound like much, but a daily 50-unit increase in GL isn’t much, either.

Those glycemic loads vary more than we may think. Some GL examples:
  • Serving of white rice: 43 units
  • Serving of unsweetened apple juice: 30 units
  • Serving of instant oatmeal: 30 units
  • Serving of raisins: 28 untis
  • A white-flour bagel: 25 units
  • Serving of cornflakes: 23 units
  • Serving of whole grain quinoa: 13 units
  • Serving of canned tomato juice: 4 units
  • Serving of chick peas: 3 units
  • Serving of grapefruit: 3 units

See Harvard Medical School’s roster of glycemic loads for more than 100 foods, below.

The Study's Large Sample
With his team, senior researcher Dr. Dariush Mozaffarian -- at Boston’s Tufts University and the Harvard School of Public Health -- collected 24 years of diet information from about 212,000 American healthcare professionals. At the beginning of the data compilation, the subjects were healthy, with weights generally considered normal.

Researchers observed that their subjects’ weights typically increased with age, but those increases varied according to the quality of protein and carbs consumed. Those correlations between increased GL and increased weight held even when researchers took lifestyle factors – like exercise – into account. 

Some of the study’s findings might seem surprising. For instance, people who ate lots of nuts, peanut butter, fish, yogurt, and low-fat cheese tended to lose weight. Contrary to the common wisdom, people who ate lots of food once thought to be “unhealthy” -- eggs, full-fat cheese and whole milk – didn’t experience measurable weight gains.

Other results carried no surprises: sugary drinks, and refined or starchy carbs -- like white bread, potatoes and white rice -- were clearly linked to weight gain.

Red and processed meats were also tied to weight gain, though potential harm was reduced if GL was generally controlled.

Unintended Consequences of Demonizing Dietary Fat 
Mozaffarian discussed how dietary fat was once demonized, a portrayal that drove people to eat more refined carbohydrates. "A lot of people still think you need to avoid fat to lose weight," he said.

For Mozaffarian, “count calories” is the new “low fat.” He thinks that when fast-food restaurants show calorie counts on their menus, consumers get the faulty impression that simple calorie-counting is a true guideline for healthful eating. But if the calorie number next to your sandwich choice is “low,” it isn’t really a smart choice if it’s mainly processed meat and refined carbs.

Lauri Wright, a spokeswoman for the Academy of Nutrition and Dietetics, supported Mozaffarian’s position on GL and the quality of protein, carbs and fat.

There’s always a caveat, and so she added, "But I don't want people to think calories don't matter.”

Her recommendation?  Healthy carbs, including vegetables, fruits and fiber-rich grains. Proteins like fish, chicken and nuts. “Good" fats like those in vegetable oils and fatty fish.

Wright continued: "You could have chicken breast on whole-grain bread, plus a salad, for lunch. For a snack, have almonds, or hummus and vegetables. Then for dinner, have salmon and vegetables."

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Like exercise, diet has been a focus on this blog from the start. I’ve written often about the highly touted Mediterranean diet, my personal favorite.  

Last week, I wrote about the curious phenomenon that we’re eating smarter and still gaining weight. That conundrum may well illustrate our failure to keep glycemic load in mind during menu preparation.

And is gaining weight a bad thing? Not according to the results of a recent study I wrote about earlier this week. Those results? Being slightly overweight actually reduces one’s risk for dementia.

Harvard Medical School lists the glycemic loads for more than 100 foods.

CBS News picked up the HealthDay account of this GL study, which was the key info source here.  

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