Pinterest and Instagram are both filled with gorgeous photos of decadent desserts and ooey-gooey macaroni and cheese recipes, and while it may be fun to dream about eating them, they may be wrecking your diet. Research from the University of Southern California says that viewing images of high-calorie foods sparks more activity in the reward areas of the brain than photos of low-calorie fare--which means you'll be more tempted to indulge in high-fat fare next time you're hungry.