For decades, nutrition dogma has held that all calories are equal. It was not supposed to matter if the energy came from a bottle of Coke or a carrot. People were told that if they wanted to lose weight they had to eat less and exercise more. The same was true for weight maintenance.
The only trouble with this article of faith was a lack of data. Nutrition studies are notoriously difficult to conduct because people have trouble sticking to their diets. Researchers often rely on people’s memories of what they have eaten. Unfortunately, study participants may not remember exactly what or how much they ate and when. People may be even more unreliable at estimating accurate quantities of what they have eaten.
Testing Diets with Different Calories from Carbs and Fat:
That’s why a new study published in the BMJ (Nov. 14, 2018) is so intriguing. The investigators recruited 164 overweight individuals in Framingham, Massachusetts, and provided them with low-energy diets to help them lose approximately 12 percent of their body weight in about ten weeks. That was just the prelude, though. The real study started after that successful weight loss and was aimed at maintaining that target weight.
The researchers randomly assigned their test subjects to one of three diets. One diet plan got 60 percent of its calories from carbohydrates. Another got 40 percent of its energy from carbs, and the third got 20 percent of calories from carbohydrates. Protein provided 20 percent of the calories in each diet, and the diets were individually adjusted for the volunteers so that they maintained their new weight for five months.
These participants weighed themselves daily on a Withings scale that automatically reported their weight to the investigators. They didn’t have to cook for themselves or make decisions about eating out: all their carefully constructed meals were provided by Sodexo, the food service provider on the campus of Framingham State University. At several points during the trial, the scientists measured energy expenditure using radioactive labeled water.
Low-Carb Eaters Burn More Calories:
As the investigators report, “total energy expenditure differed significantly by diet.” To be precise, people following the low-carb diet were burning almost 200 calories a day more, on average, than those on the high-carb diet. People who were producing the highest levels of insulin before the weight-loss diet started had the most impressive response to the low-carbohydrate regimen. Such individuals expended 300 to 400 more calories per day on the low-carb than on the high-carb diet.
In addition, two important hormones that drive hunger and fat storage also differed according to diet. Both ghrelin and leptin were significantly lower among the people in the low-carb diet group.
Will This Low-Carb Approach Work for You?
It might be difficult to generalize from this study to dieters in general. Having all your meals provided and your weight monitored every day probably means people stuck more closely to their prescribed regimens than most dieters manage. Not everyone will find they can stick to a low-carb diet over the long term.
However, the results are encouraging. Some readers of The People’s Pharmacy have been experimenting with low-carb diets for some time, and many are satisfied.
One reader shared his story:
“I have been eating a low-carb diet for a year after being diagnosed as pre-diabetic. I eat no processed foods. Instead, I eat meat, a little dairy, veggies, low-sugar fruits, no grains or extra sugars, three separate meals per day, no snacking, no fast food. I lost 30 pounds. My HbA1C is now 5.1. LDL is 84. HDL is 50. Total cholesterol is 134. It works and it’s sustainable.”
Have you tried cutting carbs? What was your experience? Tell us about it in the comment section of this post.
You can listen to us discuss a previous dietary study on Show 1126: Can You Find Your Best Diet? In it, Dr. Christopher Gardner discusses the DIETFITS study he conducted with colleagues to determine whether low-fat or low-carb diets are better for weight loss.