“You need to step it up, people,” said Jeannine Stein in the Los Angeles Times Health blog. A new study in the Archives of Internal Medicine found that obese women who stuck to their diets and exercised 55 minutes a day kept off a 10 percent weight loss, while those who only exercised for 30 minutes a day kept off only 5 percent.

But even the women who ate right and exercised the most remained overweight, said Laura Blue in Time.com, so the study reinforced the belief of many researchers that diet and exercise are not “a reliable cure for obesity.” Biology plays a part, so willpower isn’t enough to achieve thinness.

Men are a case in point, said Leslie Beck in the Toronto Globe and Mail. “The fact that a man burns more calories at rest and during physical activity makes it easier for him to eat more without gaining weight and to lose weight faster than a woman of a similar size.”

If moderation alone did the trick, said the blog The Ethicurean, rising food prices would make us all slim soon. But another new study says that 86 percent of Americans will qualify as obese or overweight by 2030, with black women and Hispanic men suffering the most. “Poor people in other countries starve, but ours get to have heart attacks and diabetes. Let’s toast our American food policies with a supersize soda!”