It doesn't matter if you try a low-fat, low-carb or high-protein diet -- all of them will work to help you lose weight as long as they cut calories, new research suggests.
The study, published this week in the New England Journal of Medicine, found that as long as a diet reduced calorie intake, it would lead to weight loss --regardless of the diet's proportions of fat, protein, or carbohydrate.
The study was called the Preventing Overweight Using Novel Dietary Strategies (POUNDS LOST). It asked 811 overweight and obese adults to try one of four diets:
- low-fat, average protein: 20 percent fat, 15 percent protein, 65 percent carbohydrate
- low-fat, high protein: 20 percent fat, 25 percent protein, 55 percent carbohydrate
- high-fat, average protein: 40 percent fat, 15 percent protein, 45 percent carbohydrate
- high-fat, high-protein: 40 percent fat, 25 percent protein, 35 percent carbohydrate
All the diets used the same calorie reduction goals and were low in saturated fat and cholesterol while high in dietary fibre.
Across the board, the participants lost an average of 13 pounds at six months and maintained a nine-pound loss at two years. Participants also reduced their waistlines by one to three inches by the end of the study.
About 15 per cent of the volunteers were able to shed 10 per cent of their body weight, which put them at a lower risk of heart disease and other health problems.
Craving, fullness, hunger, and diet satisfaction were similar across the four diets.
Dr. Elizabeth G. Nabel director of the National Heart, Lung, and Blood Institute (NHLBI), which funded the study, says the results show that no one diet approach is better than another for achieving and maintaining weight loss.
"This provides people who need to lose weight with the flexibility to choose an approach that they're most likely to sustain--one that is most suited to their personal preferences and health needs," she says.
The diets didn't just include low-calories meal plans. The participants also could go to group diet counseling sessions at least twice per month throughout the two years of the study, and individual sessions were held every eight weeks.
Everyone was also asked to do moderate-intensity physical activity, such as brisk walking, for at least 90 minutes per week.
All of the participants saw their levels of triglycerides and LDL (bad) cholesterol fall while their HDL (good) cholesterol rose and all were able to lower their blood pressure.
The study's lead investigator, Dr. Frank M. Sacks, says the study's findings should focus weight loss approaches on reducing calorie intake rather than any particular proportions of fat, protein or carbohydrate.
Dr. Yoni Freedhoff, the medical director, of the Bariatric Medical Institute in Ottawa is not surprised by the study's findings, and says the study's results are good news for those who hate dieting.
"If they are trying to adhere to a diet they don't like, it's not going to work long term. If you don't like it now, you won't like it 2 years down the road. So whatever you are doing if don't like it, try something else
"There are 200,000 diet books on Amazon. Every single one works if you eat less calories than you burn," he notes. "But if you don't like what you are eating ultimately you will go back to what you were eating before the diet."
But in an accompanying editorial, Dr. Martijn B. Katan, a professor of nutrition at Royal Netherlands Academy of Sciences, said he finds it worrying that weight loss peaked at the six-month mark in all the diets, and that so many of the study's participants started regaining weight after 12 months.
"The weight regain during the second year, although slow, suggests that in the end, many participants might have regained their original weight even if treatment had continued."
He notes that all the participants were well educated and highly motivated to lose weight, who were coached by expert professionals. Yet they could not achieve the weight losses needed to reverse the obesity epidemic.
"Evidently, individual treatment is powerless against an environment that offers so many high-calorie foods and labor-saving devices," he wrote.
Freedhoff agrees, telling CTV.ca "we shouldn't be focusing on treatment however; we need to focus on prevention, on changing the environment itself."
He says that's already starting to happen with school removing foods and drinks that are low in nutrients and high in calories from their cafeterias, and restaurants beginning to post nutritional information on menus.
"Those efforts in isolation will likely not have a dramatic impact," he says, "but if we could couple them with such things as practical curriculum-spanning educational efforts in schools, legislation to help encourage activity and healthy eating, a food guide that doesn't encourage the overconsumption of calories, the removal of the food industry from positions of influence in public health/food/fitness policy and couple that with changes to the built environment and perhaps decades of persistence and patience, then perhaps we can start reversing this epidemic."
