In a study in the Journal of General Internal Medicine, Harvard researchers analyzed 12 clinical trials, which lasted from 9 to 74 weeks and involved more than 1,150 overweight and obese people. Overall, those assigned to vegetarian diets lost about 4½ pounds more on average than those on non-vegetarian diets. Vegans (who consume no animal products at all) lost more weight than lacto-ovo vegetarians (who eat milk and eggs). Vegetarian diets are high in viscous fiber, which delays gastric emptying and intestinal absorption, leading to increased satiety.
These beverages may increase belly fat, according to a study in Circulation that analyzed data from 4,100 participants in the Framingham Heart Study over 10 years. Those who consumed sugary soft drinks regularly (especially daily) gained more abdominal fat—but not more weight overall—than people who rarely or never drank them. Excess abdominal fat, particularly the “visceral” fat surrounding inner organs, increases the risk of diabetes, cardiovascular disease, and some cancers. Diet soft drinks were not linked to abdominal fat.
In a study in the American Journal of Clinical Nutrition of overweight and obese women who were habitual consumers of diet drinks, half switched to water with their main meal, while the other half continued with diet beverages. After 24 weeks, the water group lost three extra pounds, on average. It’s not known if the results would persist over the longer term or with dieters not enrolled in a structured program, as these participants were. Previous studies on diet beverages for weight control have had inconsistent results.
In a study in Obesity, obese people were instructed to drink two cups of water 30 minutes before meals or told to just imagine their stomachs being full. All were counseled on general weight control practices. After 12 weeks, the water group lost 3 pounds more than the control group (more than 5 pounds in total), with the greatest weight loss (nearly 10 pounds) in those who reported water preloading before every main meal. Longer studies are needed to see “whether the short-term benefit of water preloading is maintained,” the paper concluded.
In a study in Obesity of overweight or obese people, half consumed portion-controlled frozen entrees for lunch and dinner over 12 weeks; the other half ate a self-selected reduced-calorie diet (control group). Those eating the portion-controlled meals lost more weight—with 74 percent of the intervention group losing at least 5 percent of initial weight, compared to 53 percent of the control group. Structured meals take the decision-making out of dieting and teach dieters about appropriate portion sizes. Look for products that are nutritionally balanced and low in sodium (many are not).
In a study in the Journal of the American Heart Association, overweight or obese women in a structured weight-loss program were assigned to one of three diets: lower-fat/higher-carb; higher-fat/lower-carb; or walnut-rich higher-fat/lower-carb. The walnut group ate 1½ ounces of walnuts a day. After six months, all groups lost about 15 pounds. But the walnut group had the most favorable changes in blood cholesterol, including a small rise in HDL (“good”) cholesterol. Walnuts supply a significant amount of alpha-linolenic acid, a potentially heart-healthy omega-3 fat.
In a study in Food Quality and Preferences, participants who wore headphones playing loud background noise ate more pretzels than those who listened to quiet noise, which allowed them to hear themselves chew. “Consumers who are distracted, or who are in the presence of environmental cues that mask intrinsic food sound, may inadvertently suppress an important consumption monitoring cue,” the researchers concluded.
They may prompt overeating, especially if you’re already feeling stressed. In a study in Environment and Behavior, participants were assigned to a quiet, distraction-free kitchen or to a disorganized, chaotic kitchen, where they were asked to write about a time when they felt either very in control or out of control. Afterwards, those in the chaotic room who had been “primed” to be in a more “out-of-control” mindset by the writing task ate more cookies than those in the same room who were primed to feel in control, and more than those in the quiet kitchen.
In a study in Pediatrics, researchers evaluated the nutritional qualities of the foods and beverages endorsed by popular recording artists in ads and at their concerts. Of 26 foods, 81 percent were high in calories and “nutrient poor.” None were fruits, vegetables, or whole grains. Of 69 nonalcoholic beverages, 71 percent were full of sugar. “Exposure to food marketing promotes excess consumption, increased purchase requests, and higher preference for the product among children and adults,” the researchers noted—and celebrity endorsements are particularly influential.