The tried-and-true way to lose weight is to burn more calories than you consume. But that’s easier said than done. Preparing low-calorie meals and keeping track of portion sizes can be expensive and time consuming, Adam Gilden and Victoria Catenacci of the University of Colorado School of Medicine wrote in an editorial that accompanies the study. It also requires a lot of discipline — not many people can withstand the temptation of a slice of cake on a co-worker’s birthday or a meal out with friends on the weekend.