Diets that are low in refined carbohydrates may help people to keep weight off longer than low-fat plans, new research suggests.
The study in Tuesday's online issue of the Journal of the American Medical Association looked at 21 men and women with an average age of 30 who'd lost an average of nearly 14 per cent of their initial weight.
Doctors and scientists are interested in finding the best ways to maintain weight loss knowing that just one in six overweight and obese adults in the U.S. said they were able to maintain weight loss of at least 10 per cent for a year in national surveys.
Study participants were randomly assigned to follow one of three diets:
A low fat diet with 60 per cent of energy from high-glycemic load carbohydrates that cause a rapid rise in blood sugar, 20 per cent from fat and 20 per cent from protein, emphasizing whole grains and a variety of fruits and vegetables.
A low glycemic index diet (40 per cent from carbohydrate, 40 per cent from fat, and 20 per cent from protein; moderate glycemic load) that replaced some grains and starchy vegetables with other vegetables, legumes and fruit.
Very low carbohydrate diet modelled on Atkin's (10 per cent from carbohydrate, 60 per cent from fat, and 30 per cent from protein; low glycemic load).
The participants followed the diets in random order, each for four weeks.
The researchers found energy expenditure differed for each of the diets.
Decreases in resting energy expenditure was greatest for the low fat diet (loss of 205 kcal/d), intermediate for low-glycemic (166 kcal/day) and lowest for the very-low carbohydrate diet (128 kcal/d), Cara Ebbeling of Children's Hospital Boston and her co-authors said.
"The results of our study challenge the notion that a calorie is a calorie from a metabolic perspective," the researchers concluded. "Total energy expenditure differed by approximately 300 kcal/d between these two diets [very low-carbohydrate vs. low-fat], an effect corresponding with the amount of energy typically expended in one hour of moderate-intensity physical activity.
"These findings suggest that a strategy to reduce glycemic load rather than dietary fat may be advantageous for weight-loss maintenance and cardiovascular disease prevention."
Successfully maintaining weight loss requires changes in behaviour and environment to stick long-term, they noted.
Although the very low-carbohydrate diet produced the greatest metabolic improvements, cortisol excretion, a hormonal measure of stress, was also highest on that diet.
Participants weren't assessed for adherence to the diets but maintenance of weight loss was tracked.
A journal editorial accompanying the study called it a well-designed study using state-of-the-art measurements.
But interpreting the results of the short-term clinical study is challenging since one diet had 10 per cent more protein than the others and since an earlier study showed that protein produces greater increases in resting energy expenditure than fat or carbohydrate, said editorialist Dr. George Bray of Pennington Biomedical Research Centre in Baton Rouge, La.
Changing dieters' behaviour
Obesity is one of the most important and frustrating problems for physicians to treat, Bray said.
"Although the exact relationship between dietary composition and weight maintenance remains unclear, calorie restriction is more important than diet composition in administering weight-loss regimens," he concluded.
A second randomized clinical trial appearing in the same issue of the Journal of the American Medical Association that involved 363 obese and overweight adults suggested that people assigned to a standard weight-loss program lost more weight than those in a stepped up program that adjusts the frequency and intensity of treatment based on weight-loss goals.
The stepped up approach cost half as much per person ($785 versus $1,357) and by the end of the study, both groups had regained some weight.
"This trial thus shows the novel approach of spending more time and effort on patients who need it most may be more economical than implementing a standard protocol for all participants regardless of their response," Bray said.
Both studies were funded by the U.S. National Institutes of Health. Ebbeling's also received funding from the New Balance Foundation.
ALSO: When carbs are good: here are 10 carbs to eat before and after workouts.
Even though many stay away from pastas during diets, whole grains are a great source of complex carbs, which can store energy in our muscles for a longer period of time.
Another great grain, brown rice is full of fibre and can decrease the risk of colon cancers.
Easy on the syrup! Whole grain pancakes are full of fibre and taste great with fresh fruit and honey.
For those of you who love morning cereal, a bowl of fibre-filled whole grain cereal is an easy way to get full. Trying to keep it healthy? Opt for skim milk.
Unsalted whole grain crackers also fuel your body with energy.
A diet including whole grains can decrease your risk of cardiovascular disease, metabolic syndrome and even gum disease.
The most versatile thing about smoothies is that they allow you to add in your own ingredients. Don't be afraid to use fresh veggies, flax seeds and even green tea along with your favourite fruit.
If you're trying to avoid dairy, chocolate milk can easily be made to fit your needs.
Yogurt is rich in calcium and full of protein but it also lets you experiment with add-ons like granola and fresh fruit.
Again, customize your own bar and fill it up with fibre and protein. Check out this recipe by Kate Slate.
Preparation time: 15 minutes Cooking time: 10 minutes Servings: 4 Ingredients: 1 pkg ( 375 g ) whole wheat penne rigate 1/2 cup ( 125 ml ) chopped sweet or white onion 1 cup ( 250 ml ) loosely packed, chopped fresh basil leaves 1/2 cup ( 125 ml ) loosely packed, chopped fresh parsley leaves 1 tbsp ( 15 ml ) sherry vinegar or balsamic vinegar 1/2 tsp ( 2 ml ) each salt and pepper 4 cloves garlic, finely chopped 2 1/2 cups ( 625 ml ) chopped, ripe, on-the-vine tomatoes 1 tbsp ( 15 ml ) extra virgin olive oil Instructions: Toss the tomatoes with the onion, basil, parsley, vinegar, salt, pepper and garlic. Let stand for at least 10 minutes. Cook the penne according to package directions. Drain well and toss with the reserved bruschetta mixture. Toss mixture with olive oil and adjust seasonings before serving. Serve warm or at room temperature. Recipe courtest of Catelli