But there was a catch. Blood samples taken while participants were on the low-carb diet revealed spikes in cholesterol and other measures of heart disease, stroke and even diabetes risk. [7 Foods Your Heart Will Hate]

The low-glycemic-index diet offered the best in terms of modest improvement in metabolism and reducing the risk of various chronic diseases, Ludwig told LiveScience. The low-fat diet — what's recommended by the U.S. government and the American Heart Association — performed the worse, Ludwig added, because it decreased the metabolism rate and raised the risk for diabetes and metabolic syndrome.

Processed vs. non-processed

At first glance, this study might appear to rule out a so-called "low-fat" diet. Not so, says Dean Ornish, founder of the Preventive Medicine Research Institute in Sausalito, Calif., and of the low-fat diet that bears his name.

"The choice is not between a diet that is low in fat yet high in sugar versus one that is low in sugar but high in fat, or an in-between diet," Ornish told LiveScience. "An optimal diet is predominantly whole foods that are low in fat and low in sugar and [low in] other high-glycemic-index foods," a diet he has long advocated.

Ludwig agreed that a low-fat diet could work provided that the carbohydrate component of the diet is low on the glycemic index. But this is complicated in an American diet, he said, because even whole grains, when heavily processed, can spike the blood sugar. Soft, whole wheat bread can have an identical glycemic index profile as white bread.

"We believe that low-glycemic-index diets are easier to stick to on a day-to-day basis, compared to low-carb and low-fat diets, which many people find limiting," said Ebbeling. "Unlike low-fat and very-low-carbohydrate diets, a low-glycemic-index diet doesn't eliminate entire classes of food, likely making it easier to follow and more sustainable."

"The focus on fat reduction is a waste of energy," added Ludwig. "Low-carb has downsides, too."

Christopher Wanjek is the author of the books "Bad Medicine" and "Food At Work." His column, Bad Medicine, appears regularly on LiveScience.

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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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