All Calories (and All Foods) Are Not Created Equal
A recent study makes the point that what you eat matters as much as how much you eat. That is, 100 calories of carrot sticks or grapes and 100 calories of deep-fried anything are not the same, in that our bodies do not burn them off in the same way.
In particular, more research suggests that the body treats foods made from highly processed carbohydrates (white flour, sugar) differently. Eating these results in spikes in blood sugar and insulin and in our retaining fat rather than burning it off.
In the study (published in the Journal of the American Medical Association), Cara Ebbeling and David Ludwig, the associate director and director of the New Balance Foundation Obesity Prevention Center of Boston Children’s Hospital, looked at how well people were able to maintain weight loss. As New York Times writer Mark Bittman points out, “few people maintain even a small portion of their weight loss after dieting.”
21 overweight and obese young adults who had lost 10 to 15 percent of their body weight were randomly asked to follow each of three diets for four weeks:
Diet #1. A standard low-fat diet with 60 percent carbohydrates (with fruits, vegetables and whole grains, though not unprocessed ones), 20 percent from protein and 20 percent from fat — a diet that has been widely recommended for 30 years.
Diet #2. An ultra-low-carb diet with 10 percent of calories from carbohydrates, 60 percent from fat and 30 percent from protein — what is popularly known as the “Atkins” diet.
Diet #3. A low glycemic diet, with 40 percent carbohydrates (specifically, minimally processed grains, fruit, vegetables and legumes), 40 percent fat and 20 percent protein.
On diet #1, the standard low-fat diet, participants burned the least amount of calories. They burned 350 calories (about an hour of moderate exercise or, notes io9, a Snickers bar) more a day on #2, the “Atkins” diet. They burned 150 calories more (about an hour of light exercise) on the low glycemic diet.
So, eating some foods does makes you burn off more calories. However, the “Atkins” diet, while providing the best metabolic benefits in the short run, poses health risks in the long term. It raises levels of CRP (c-reactive protein), a measure of chronic inflammation, and cortisol, a hormone that mediates stress, and both of these are “tightly linked to long term-heart risk and mortality,” says Ludwig. The best diet over time is #3, the low glycemic one because, along with the (milder) metabolic benefits, it does not require that you remove “an entire class of nutrients” from your diet. Doing so is, says Ludwig, “not only hard from a psychological perspective but may be wrong from a biological perspective.”
The real surprise is about the standard low-fat diet. In fact, Ludwig says that it is actually “the worst for most outcomes, with the worst effects on insulin resistance, triglycerides and HDL, or good cholesterol.”
The culprit in the “obesity pandemic” — Bittman observes that many experts consider “epidemic” to be “no longer a strong enough word” — is the amount of over-processed carbohydrates we eat. He cites statistics showing that “at least a quarter of our calories come from added sugars (seven percent from beverages alone), white flour, white rice, white pasta,” as well as “white potatoes” and, let’s face it, beer. So, according to Ludwig, what we need to add to our diet is minimally processed carbohydrates. He even suggests this:
If you take three servings of refined carbohydrates and substitute one of fruit, one of beans and one of nuts, you could eliminate 50 percent of diet-related disease in the United States.
The study makes a real case for getting “Big Food” out of our diets. Drinking 100 calories of sugary “fruit-based juice drink” really is not the same as eating 100 calories of actual fruit: Some calories are more beneficial than others.
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