A calorie is a calorie, goes the popular mantra. But now doctors and dieticians might have to eat those words.

Researchers have found that not all calories are created equal and that the types of calories you eat, particularly after losing weight, can have a profound effect on how efficiently your body burns calories and keeps off unwanted pounds.

The ideal diet that promotes a fast metabolism — that is, your body's ability to quickly burn off calories — as well as promotes long-term health in terms of disease-free organs appears to be (surprise!) fresh vegetables and whole grains or any foods that reduce the surge of blood sugar after a meal.

These foods are said to have a low glycemic index and are generally foods that are not processed. The Mediterranean diet is one example.

The study, led by researchers at Boston Children's Hospital, is detailed in the June 27 issue of the Journal of the American Medical Association.

Blame it on evolution

Anyone who has struggled to lose weight knows that the harder part is keeping off that weight. One of the reasons is that, after weight loss, the rate at which people burn calories decreases, reflecting a slower metabolism.

Blame it on evolution: Your body doesn't want to lose weight, so it becomes efficient at doing more with fewer calories when faced with times of famine, which in these modern times is called a diet. As a result, some dieters find themselves packing on pounds even while on a calorie-restricted diet because their metabolism has become slower.

Cara Ebbeling of the New Balance Foundation Obesity Prevention Center at Boston Children's Hospital, first author on the study, and her colleagues have found that what you eat can significantly affect your metabolism rate. A diet full of processed foods and simple carbohydrates, which have a high glycemic index, eventually will lead to a slower metabolism. [7 Diet Tricks That Really Work]

This index, a scale from 0 to 100, is a measure of how quickly a carbohydrate is digested and released into the bloodstream as glucose. So, 200 calories of corn flakes (93 on the glycemic index), or a diet filled with such processed foods, can continuously spike the blood with glucose and trigger a cascade of events that ultimately lead to more weight gain compared to 200 calories of hummus (6 on the glycemic index).

Not necessarily fat vs. carb

Specifically, Ebbeling's group studied three dietary paradigms: an Atkins' low-carb diet (60 percent of calories from fat, 10 percent from carbs); a mixed diet with foods generally low on the glycemic index (40 percent of calories from fat, 40 percent from carbs); and a low-fat diet with a mix of carbohydrates generally high on the glycemic index (20 percent of calories from fat, 60 percent from carbs).

Patients, who had recently lost weight, were placed on each of these diets for four weeks. They lived in the care of the researchers, who controlled meals and measured various aspects of their metabolism and blood profiles.

In terms of metabolism, the Atkins-like diet was the winner, said the study's senior author, David Ludwig, director of the obesity center. While on the low-carb diet, patients burned 300 more calories each day during normal activities compared to the time spent on the low-fat diet. Three hundred calories is about the amount of energy burned in an hour of moderate exercise, which the low-carb dieters are getting for free, Ludwig said.

6 Comments

1. 1. jerryd 03:08 PM 6/28/12

   
   Having just lost 50 lbs it wasn't that hard, just stop eating so much high cal food. Most days I eat around 1500 cal, 5'8'' male, of low cal density foods.
   
   I start with chocolate oatmeal made with 50% of the water, low sugar chocolate surup? and 1oz of chocolate chips only comes to 300 cals along with a banana.
   
   Lunch/dinner is a plate of veggies with 2-4oz of flavorful meat plus higher fiber, lower cal bread and potatos/beans/rice of 400-700 cal/meal.
   
   And sometimes a 100-300 cal snack. On days I feel hungry I just eat 2000cal/day and drop back to 1500 in a day or 2.
   
   I lost 50lbs in 6 months that way. So stop stuffing yourself and learn to cook, etc better foods and not processed foods.
   
   I should mention I only spend $120/month on food here in Fla so it doesn't have to cost that much.

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2. 2. leoluca criscione 05:28 PM 6/28/12

   As shown in figure 3 of the paper, the positive effect of the very-low carb diet on REE was not consistent in all subjects! This might indicate that other mechanisms of action rather the diet as such are involved. As mentioned in the paper: “The very low-carbohydrate diet involved more severe carbohydrate restriction than would be feasible for many individuals over the long term”. This might have produced stress in some individuals as indicated by the increased cortisol excretion! Stress might have also increased heart rate, which might explain the positive effects on metabolism. Unfortunately, heart rate was not measured in this study, as senior author, David Ludwig, just wrote to me in a email. Dr. Ludwig, however, finds my hypothesis "interesting". May be a clarifying answer on whether stress is responsible for the effects on metabolism with the very low carb diet, could be given by correlating cortisol levels and metabolism.
   I asked Dr. Ludwig to investigate my hypothesis.
   Healthy greetings from Switzerland,
   Leoluca Criscione PhD, former obesity researcher
   
   

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3. 3. DaleBent 10:59 PM 6/28/12

   I am surprised that neither your article or the studies cited don't mention that the properties of low-glycemic carbohydrates were clearly explained by Dr. Barry Sears in his books describing the Zone diet, the result of investigations dating back to the 1990s. Dr. Dale Bent.

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4. 4. acharya 01:49 AM 7/1/12

   After a major MI in Jan 1998, (identified as having unstable angina) and refusing bypass surgery and medication, I followed an Indian diet based on the Ornish diet principles but after a few months began to modify it. Within a few months I was better and began leading a fairly active retired life. I still follow an Indian diet modified over the years with far more selected vegetables , the inclusion of E V Olive oil, a little ghee etc. There is little processed food in my diet and most of it is fresh. In a family where most over 60 are diabetic at 72 my blood sugar level and BP and cholesterol are optimal.A modified Indian diet can do the same as a mediterranean diet.

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5. 5. acharya 02:37 AM 7/1/12

   I may amplify. The fat content of my food is about 15 to 20% a day, with the rest a mix of complex carbohydrates and proteins(lentils and beans)with barely 20% cooked grains. About 1/2 tsp of psyllium twice a day between meals generally keeps cholesterol and blood sugar under great control. My sugar consumption is about 3/4 tsp a day.As you can surmise the diet is vegetarian.

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6. 6. Surf_punk in reply to leoluca criscione 07:30 PM 3/1/13

   I know this late to the game but the fact that stress causes a change in metabolic rate is a known to anyone who enjoys skillfull aquisition such piano playing and body building through the secreation of growth hormone by the pituitary to rebuild "damaged" muscule mass through what else stress on the tissue breaking it down and then very quickly rebuilding it to handle even more stress etc etc. It makes sense that controled levels of stress help us to shape ourselves literally and we can choose to do this consciously. This I learned intellectually from reading the Zone by B Sears from 1995 and I have experienced this directly through intermediate yoga and instrumental(music)practice.
   
   thanks for your origonal comment
   SP

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