Low-carb diets are nothing new. If you haven’t tried the Keto diet or the Atkin’s diet, you’ve likely heard of them. Many people consider these “fad” diets, and they very well may be, but fad or not, research does suggest that cutting carbs could be an effective way for people who have lost weight to keep it off.
Click for larger version. Source: BMJ
One study, which looked at people who were trying to maintain weight loss, found that the participants burned more calories when they adhered to a low-carb diet, versus a high-carb diet. Among those with the same average body weight, those who ate a low-carb diet burned about 250 more calories a day than those who ate a diet high in carbohydrates, even though both groups engaged in similar levels of physical activity.
David Ludwig, co-principal investigator of the study and co-director of the Boston Children’s Hospital’s New Balance Foundation Obesity Prevention Center, said:
“The type of calories you consume affect the number of calories you burn. These novel effects of food, beyond calorie content, may help make long-term weight control easier and more effective.”
The study was designed to test what is known as the “carbohydrate-insulin model of obesity.” Here’s the gist of the model: processed carbs that have a high glycemic index cause fat cells to store excess calories instead of burning them. Foods that rank high on the glycemic index dump sugar into the bloodstream more quickly than foods that are low on the index.
Studies suggest that in the short-term (about 2 weeks or less), there is no difference between high-carb and low-carb diets in terms of daily calories burned. However, Ludwig and his colleagues spent 5 months investigating the potential differences for the latest study.
Low-Carb vs. High-Carb
Click for larger version. Source: BMJ
For the study, the researchers recruited 164 overweight adults aged 18 to 65 who had already lost 10% of their body weight. The participants were assigned to 1 of 3 diets, all varying in carbohydrate content, for 20 weeks. [2]
Researchers provided the volunteers’ meals, all of which contained the same daily calorie count and 20% protein.
- One group’s diet contained 20% fat and 60% carbs.
- Another group’s diet consisted of 40% fat and 40% carbs.
- The 3rd group’s diet contained 60% fat and 20% carbs.
Those who consumed the lowest levels of carbs had burned the most calories at the end of the study period. These participants also had lower levels of hunger, and the hormones grehlin and leptin. Grehlin is a hormone that increases appetite, while leptin signals the brain and other organs to decrease appetite, among other things.
Participants in the low-carb group burned 209 to 278 calories a day more than those in the high-carb group, which meant they burned 50 to 70 calories more a day for every 10% decrease in carbs to their total energy intake.
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Participants who secreted the most insulin at the start of the study saw an even more startling difference in energy expenditure: those on the low-carb diet burned up to 478 calories a day more than those in the high-carb group. Ludwig said this means that those in the low-carb group could expect to lose about 20 pounds more a year than those in the high-carb group.
Dr. Rekha Kumar, an endocrinologist and obesity medicine specialist at NewYork-Presbyterian and Weill Cornell Medicine in New York City, who was not involved in the study, said:
“Most studies are looking at inducing weight loss. This one is about loss maintenance. And it’s asking, is there a particular macro nutrient composition that can result in a higher calorie burn?”
Click for larger version. Source: BMJ
He added that the fact that people with higher insulin levels “had the biggest impact allows you to say this is quite valid. That’s because these are the people – the ones who have issues with blood sugar and insulin – that you would expect to respond.”
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This is just more evidence that going low-carb or adopting a ketogenic diet can lead to weight loss.
Kumar said:
“I think there’s a tendency to go all or nothing, saying just eat a low-carb diet and it will keep the weight off. Maybe a low-carb diet can help, but so can increasing exercise.”
The study was published November 14 in the BMJ.
Sources:
[1] Live Science
[2] Reuters