Bonnie Modugno, MS, RD - Eating More Protein, less refined starch is best to lose weight
Higher protein, lower refined carbohydrate diets best help patients maintain weight loss. A six month diet study recently published in the New England Journal of Medicine shows that after intense weight loss, a higher protein diet coupled with low glycemic carbohydrate resulted in less weight regained. Arne Arstrup, one of my favorite researchers, recently completed the Diogenes study with colleagues at the Faculty of Life Sciences, University of Copenhagen.
A total of 772 European families participated in the study, which was comprised of five different diet types:
- A low protein diet (13% of calories–a typical American diet) coupled with high glycemic carbohydrates
- A low protein, low glycemic carbohydrate diet
- A high protein (25% calories), high glycemic carbohydrate diet
- A high protein, low glycemic carbohydrate diet
- A control group which followed current dietary guidelines (high carbohydrate diet, but using lower glycemic foods)
All the adult subjects were restricted to 800 calories a day for eight weeks prior to the study. The average weight loss was 11 kg–twenty four pounds. After the initial eight week, the subjects were divided into one of the five groups for a six month diet intervention. Key findings are summarized below:
1. People eating a low protein, high glycemic diet re-gained about 3 1/2 pounds during the study.
2. People eating the higher protein, lower glycemic diet re-gained a bit over 1.5 pounds during the study.
Both results are rather impressive, considering the duration of the study. What is most interesting is the experience of the participants, a key element not often assessed in weight loss research.
MORE SATISFIED ON HIGHER PROTEIN, LOWER GLYCEMIC FOODS
Despite the challenges of working with the glycemic index (see below), the study results are noteworthy. Participants eating more protein and less refined carbohydrate felt more satisfied. The researchers reported that the participants could eat until they were “full” without counting calories or gaining excessive weight.
More participants eating a higher protein diet completed the study. Only 25% of the participants eating the higher protein diet dropped out compared to those eating the low protein higher glycemic foods. 37% of those participants dropped out. Overall 71% of the participants completed the six month study.
The lower drop out rate for families eating a higher protein intake is a very telling measure. People have a difficult time following a plan when they don’t feel satisfied. It is exhausting to restrict yourself day after day when you don’t feel content and every thought is about food.
LESS CHILD OBESITY
Even more impressive, the prevalence of overweight children in the study decreased significantly. Since families were enrolled in the study, the children ate what the parents were eating. The prevalence of overweight children in families eating the higher protein, low glycemic carbohydrate diet dropped from 46 to 39% over the six month course of the study.
I often what would happen to child obesity if we were able to raise our children in a world that did not offer highly refined sugars and starches at every meal, every snack, and every special occasion. These highly refined foods are the most accessible, least expensive, and most immediately gratifying. Most snack foods, desserts and sodas have a high glycemic value and a kind of “sin factor” appeal.
RETHINKING DIETARY GUIDELINES
Drs. Astrup and colleagues are quick to point out that a higher protein, lower glycemic dietary protocol doesn’t match up with European dietary guidelines. “The official dietary recommendations are not sufficient for preventing obesity.”
That goes for current US Dietary Guidelines as well. The proposed 2010 USDA guidelines continue to focus on reducing fat and saturated fat with only modest attention to sugar and refined starch. USDA farm policy continues to subsidize corn, soy and wheat–making all those highly refined foods, snacks and treats very inexpensive.
A NOTE ABOUT HIGH AND LOW GLYCEMIC FOODS
Foods with carbohydrate content impact blood glucose levels. A food that increases blood glucose level dramatically is thought to have a high glycemic index. A food with a glycemic index over 70 is considered “high”, 55-70 is considered “medium”, and under 55 is considered “low”.
Many factors influence the glycemic value of foods: the degree of processing, extent of cooking, even the temperature the food is eaten. In order to reduce the glycemic index of foods the participants were given specific instructions regarding food choices. They were told to eat pasta al dente and preferably cold, to eat brown or parboiled rice over white rice, and to cook potatoes as little as possible.
The glycemic index is not a perfect tool, which is why the index is somewhat controversial. Many people assume foods with sugar have a high index. That is true when sugar is consumed alone. As soon as fat and protein are combined with the sugar, the food typically exhibits a lower index. Both the fat and protein buffer the glycemic response. In this way ice cream (60) and sweetened yogurts (36) boast a lower glycemic values than white bread (70) or a soda (65).
GLYCEMIC LOAD versus GLYCEMIC INDEX
Another complexity with the glycemic index is that each food was evaluated using 50 gram of carbohydrate in the food. This is different than simply measuring 50 gram (about 1.5 ounces) of the food. Carrots boast a higher index (72) than typical sweets. This has lead many people to consider carrots taboo–too high in sugar.
To consume fifty grams of carbohydrate from jelly beans you get to eat about 19 large jelly beans. To consume fifty grams of carbohydrate in carrots you need to eat 21.6 ounces–about 1 1/3 pounds– of raw carrots. Since most people would cry out with a stomach ache before they finished over a pound of carrots, some researchers prefer to talk about “glycemic load”.
The glycemic load is a concept that takes into consideration the amount of a typical portion in addition to the glycemic value of the individual food. I wonder what the glycemic index is for a handful of carrots versus a handful of jelly beans. That would be a fair comparison using the more practical concept of glycemic load.