Do you work out on an empty stomach? In a recent study, European researchers found that cyclists who trained without eating burned more fat than their counterparts who chowed down, but I'm not convinced that running on empty is a smart strategy. In the study the researchers observed seven cyclists who trained three days a week, including an intense cycling session without eating. Another seven people followed an identical regime, but didn't skip the pre-cycling meal. Members of the group that didn't eat performed worse during the intensive training, but they burned a higher proportion of fat to carbohydrates than the other group.
As a nutritionist who is board certified as a specialist in sports dietetics (CSSD), here are my thoughts: first it was a small study (14 people total) and while the meal skippers burned more body fat, the more interesting finding is that they struggled to get through the workout. In my opinion, it's not worth burning slightly more body fat if it means performing worse and running the risk of a) eating away at your precious muscle mass for fuel (which wasn't measured in this study but is known to happen to underfed athletes) or b) passing out from low blood sugar (muscle can be broken down and converted into blood sugar, but fat cannot).
I work with a lot of different types of competitive and professional athletes, and the one thing they all have in common is that performance rules. Whether you run, cycle, play tennis, golf or baseball, you want to do "what you do" well and feel like you're on top of your game. And even if your activity of choice isn't competitive, like hiking, yoga or dancing, I'm sure you want to feel energized and enjoy it; and that's hard to do if you're underfueled.
Every person's body is different and you know yours better than anyone else's. I've counseled many athletes who prefer to get up and run before breakfast, but they'll often drink fluids with calories during their run or eat less before shorter runs. Meals and snack are meant to fuel your activity in the hours to come, so ideally it is best to eat before you're going to be active. If you do, you won't prevent body fat from being burned. And even if you do burn slightly less body fat than you would in a "fasted state" you'll probably get a better workout, which is the real goal. Bottom line: do what feels right for your body and remember that regardless of the exact proportions, every workout burns fat. So if you usually head to the gym an hour after your morning oatmeal, this study offers no reason to nix it!