High-Protein Diet May Promote Weight Loss
Researchers from the University of Missouri in Columbia published a new study in the April issue of the journal Obesity that evaluated the effectiveness of consuming more frequent high-protein meals. Eating more meals during the day with higher protein content is a common diet strategy Americans use to increase healthy eating and promote weight loss.
The study consisted of 27 overweight and obese men with a mean age of 47 and a mean body mass index (BMI) of 31.5 kg/ m2 at baseline. They were randomized to groups that consumed either a highprotein, calorie-restricted diet or a normalprotein, calorie-restricted diet for 12 weeks. Beginning week 7, participants were then randomized to consume their respective diets as either 3 meals per day or 6 meals per day for 3 consecutive days. Indices of appetite and satiety were assessed every waking hour in the third day of each pattern. The researchers found that the participants consuming the high-protein diet experienced greater fullness throughout the day than the normal-protein group (P <.005). In contrast, frequency of meals did not influence daily hunger or fullness.
Heather J. Leidy, PhD, lead author of the study, concludes from the results that an “energy-restriction diet containing a moderate increase in dietary protein consumed in [3 meals per day] leads to better appetite control and satiety in overweight and obese men.” Future studies, Dr. Leidy writes, should also focus on the subgroup of patients who skip meals, “which is suggested to negatively influence appetite control.”
Diet and Exercise Recommended in Older Adults Who Are Obese
Currently, there is little evidence to support weight-loss interventions in older adults who are obese, despite the increased prevalence of obesity in this population. There is also some concern that a decreasing BMI due to weight loss in this population will accelerate age-related loss of muscle that leads to sarcopenia.
In a randomized, controlled, 1-year trial published in the March 31 issue of the New England Journal of Medicine, researchers from the University of New Mexico in Albuquerque evaluated the independent and combined effects of dieting and exercise in 107 adults who were 65 years or older and obese.
Participants were randomly assigned to a control group, a weight-management (diet) group, an exercise group, or a weight-management-plus-exercise group. The primary outcome was the change in score on the modified Physical Performance Test. The researchers found that after completion of the study, the score on the Physical Performance Test increased more in the diet-exercise group than in either the diet or exercise groups.
Further, lean body mass and bone mineral density at the hip decreased less in the diet-exercise group (reductions of 3% and 1%, respectively) compared with the diet group (reductions of 5% and 3%, respectively; P <.05). The scientists concluded that for obese seniors, as in other patient populations, the combination of diet and exercise is associated with a greater improvement in physical function than either alone.
Fatty Liver Disease Benefits from a Low-Carbohydrate Diet
A complication of obesity, nonalcoholic fatty liver disease (NAFLD) has been estimated to affect approximately 71 million Americans. NAFLD is associated with triglyceride accumulation in liver cells and sometimes hepatic steatosis and cirrhosis. Efforts to lower triglycerides through weight loss have been studied, but carbohydrate restriction, a proposed method to decrease triglycerides, has not.
Researchers from the University of Texas Southwestern Medical Center in Dallas designed a study that enrolled 18 subjects with a mean age of 45 years and a mean BMI of 35 kg/m2 to a carbohydrate-restricted (<20 g/day) or calorie-restricted (1200-1500 kcal/ day) diet for 2 weeks. Hepatic triglycerides were measured before and after study completion. Although mean weight loss was similar between the groups (-4 kg in the calorie-restricted group and -4.6 kg in the carbohydrate-restricted group; P = .363), liver triglycerides decreased significantly more in the carbohydrate-restricted subjects than in the calorie-restricted subjects (-55 vs -28; P = .008). The researchers attribute this advantage of a carbohydrate-restricted diet to enhanced lipid oxidation and increased ketone production. Dietary carbohydrates serve a primary role in lipid synthesis.
Nevertheless, the researchers caution that although carbohydrate restriction for a short duration is associated, in this study, with a decrease in liver triglycerides, this study did not determine the therapeutic superiority of one diet. Studies of longer duration are needed in order to assess if one diet has benefits over the other in decreasing or preventing NAFLD long-term. PT
Fast Fact: The thinnest state in the United States in 2010? Colorado, with an obesity rate of 18.9%--the only state that had an obesity rate below 20%.