A 12 week study conducted by the Harvard School of Public Health and presented in October 2003 to the North American Association for the Study of Obesity found that subjects on a low carb regimen lost just as much weight as those on a standard high carb, low fat diet.
The shocking part was that the group on the Atkins diet could eat 300 more calories than the group eating the conventional high carb food pyramid diet. This left researchers scratching their heads saying,
“It doesn’t make sense… it defies the laws of thermodynamics.”
“A lot of our assumptions about a calorie is a calorie are being challenged,”
Unfortunately, some of the Atkins troops were quick to interpret the results as meaning, “See, I told you calories don’t count.”
Actually, calories do count and the explanation for these results is quite simple.
A calorie is NOT just a calorie. If all calories were created equal then a 2000 calorie diet of Krispy crème doughnuts would have the same effect as a 2000 calorie diet of chicken breast and salad vegetables. Do you think these two diets will have the same effects on your health and body composition?
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Certain foods and certain diets DO give you a metabolic advantage. One advantage is the effect of a diet’s composition on your hormones; namely insulin and glucagon.
A second advantage is called the thermic effect of food. The thermic effect of food means that a certain number of calories are used just to digest and absorb the food, leaving a net calorie value substantially less than the total amount of caloric energy that was contained in the food.
For example, a lean protein food such as chicken breast has a thermic effect of around 20-30%. This means that for every 100 calories of chicken breast consumed, the NET energy utilized by the body is only 70-80 calories. (Some people call this “negative calories.”)
Stated differently, this means you really CAN lose weight on a higher calorie intake if you eat foods with a high thermic effect.
What’s especially interesting –providing confirmation of the metabolic advantage of a high protein diet – is that the foods provided in this study were low carb, but NOT typical Atkins fare. Instead of lots of red meat and saturated fat, the subjects in this particular study ate mostly fish, chicken, salads, vegetables and unsaturated oils.
I think study’s director, Penelope Green, hit the nail on the head when she said, “Maybe they (the low carb, high protein group) burned up more calories digesting their food.”
Truth is, not one study has ever proven that you can “eat as much as you want” on Atkins or any diet. Even when a diet provides a metabolic advantage, AFTER that advantage is factored in and you look at NET calorie utilization, you are still left with the calories in versus calories out equation.