(CBS News) Does it feel like your diet isn’t helping you keep off pounds in the long run? A new study suggests that simply cutting calories might not do the trick: It may depend on what kind of calories you’re snipping from your daily intake.
The study, published on June 27 in The Journal of the American Medical Association, says that low-glycemic diets that compliment a person’s changing metabolism are the best at helping keep the pounds off.
“Our findings suggest that actually trying to restrict either carbs or fat is not the best way (to achieve long-term weight loss) and instead to focus on the quality of the fats and the quality of the carbs,” Dr. David Ludwig from Boston’s Children’s Hospital told CBS This Morning (CTM).
Ludwig explained on the Boston Children’s Hospital blog that after individuals lose weight, the rate at which they burn calories slows down. This makes it difficult to maintain the continued weight loss. With the study, researchers were attempting to find a diet that would continue the accelerated calorie-burning rate while taking into account the body’s new metabolism.
“Keeping weight off - even under the best circumstances - is difficult,” Ludwig told the Boston Children’s Hospital blog. “But lining up biology and behavior can help.”
For the study, researchers recruited 21 young adults who were overweight and obese. After losing 10 to 15 percent of their body weight (on average 30 pounds), they were placed on one of three diets that contained the same amount of calories, albeit from different sources, in random order for four weeks each: a low-fat diet (60 percent of calories from carbohydrates, 20 percent from fats, 20 percent from proteins; high glycemic load), a low-glycemic index diet (40 percent of calories from carbohydrates, 40 percent from fats, and 20 percent from protein;s moderate glycemic load) and a very low-carbohydrate diet (10 percent of calories from carbohydrates, 60 percent from fats, and 30 percent from proteins; low glycemic load).
Doctors measured both the pre-weight loss numbers for resting energy expenditure (REE) - the amount of calories required for a 24-hour period during a non-active phase - total energy expenditure (TEE) - all energy expended in a 24-hour period including the REE - hormone levels and metabolic syndrome components, as well as the stats during each period the subject was on the various diet.
The researchers found that compared with the pre-weight loss numbers, the decrease in REE and TEE was greatest in the low-fat diet, followed by the low-glycemic index diet and finally the very low-carbohydrate diet. This means the low-fat diet slowed down metabolism the most. Hormone levels were negatively affected by the low-carbohydrate diet, meaning that inflammation increased and the risk of disease also increased as well.
The overall winner was the low-glycemic diet, which offered both a healthy and an easy way to keep metabolic rates up. To keep a low-glycemic diet, people must eat fiber-rich, natural carbohydrates, proteins and healthy fats, including nuts, avocados or olive oil. Grain products that have a low level of processing are also encouraged, while fruit juice and soda are to be avoided. Sugar can be consumed, but only with a balanced meal and in moderation. Drinking water is encouraged.
“A low-glycemic diet offers a healthy variety without eliminating entire classes of foods - like fat or carbs - so it’s naturally more sustainable,” Ludwig said in the blog. “This is especially helpful for children, since variety and flexibility make it easier for them to follow.”
Ludwig told CTM that since our bodies are used to eating traditional carbohydrates for thousands of years - like steel-cut oats over instant oats - they digest and raise blood sugar levels slower so there isn’t a “surge and crash.”
“But all of the refined carbs that invaded our diets with the low-fat craze seems to lead to metabolic changes not only making us hungrier, but causing metabolism to fall. And that combination is a recipe for weight gain,” Ludwig explained to CTM.