5. There's a "marriage diet." Husbands and wives often begin eating like each other, suggests a study published in September in the American Journal of Public Health. After analyzing the eating behavior of more than 3,000 people, researchers observed that spouses, more than friends or siblings, had the greatest effect on each other's eating habits, for better or for worse. That's likely because of the strength of the shared environment; most husbands and wives regularly prepare food for each other. Another study, presented at the annual meeting of the American Sociological Association in August, found that marriage and divorce influence the sexes differently. While married men and women tend to gain more weight than their single counterparts, women generally pack on more pounds than their husbands. Two years after divorcing, separated partners were heavier than couples who remained married, but men recorded larger weight gains than women.
6. Salt questioned, bad fats flagged on heart health. Two studies published by the Cochrane Collaboration, a nonprofit research organization, shed light on the link between diet and heart health. In one, researchers took a hard look at salt. They analyzed seven studies with a total of roughly 6,500 participants and concluded that reducing salt intake might not delay death or prevent cardiovascular disease, as some research has suggested. Still, the researchers said, this "does not mean that asking people to reduce salt should be stopped." Shunning salt has been shown repeatedly to reduce blood pressure. The jury's still out.
Another Cochrane analysis focused on types of fat. After reviewing 48 studies, researchers reported that replacing saturated fats (like butter) with unsaturated fats (monounsaturated fats like olive oil and polyunsaturated fats like canola and peanut oil) may reduce risk of heart disease—but they couldn't say whether the mono- or polyunsaturated varieties were best. Regardless, disease protection appeared to be strongest when the switch was made for at least two years, the researchers said. Surprisingly, they found no clear heart benefit to reducing total fat consumption.
7. "Freshman 15" debunked. Where did the idea come from that first-year college students are likely to add 15 pounds or so? It's more like an average of 2.4 pounds for women and 3.4 pounds for men, according to a study in the December issue of Social Science Quarterly. The findings are based on data from a survey that tracked 7,418 young people. For students who picked up more weight than average, heavy drinking and juggling a job and school were most often to blame.
8. Hormones try to defeat weight loss. Certain hormones may make it difficult for some dieters to keep the weight off, according to an October study by an Australian research team in the New England Journal of Medicine. In 35 overweight or obese patients who lost at least 10 percent of their body weight after following an ultralow-calorie diet for 10 weeks and then got diet counseling for the next 52 weeks, the level of several key hormones at 62 weeks rose or fell in ways that seemed to encourage regaining the lost weight. Ghrelin, which stimulates the appetite, went up as participants slimmed down. Their feelings of hunger were also tracked; the participants were hungrier at the 62-week point than they were when the study started.